ARTICLE | doi:10.20944/preprints201912.0265.v1
Subject: Biology And Life Sciences, Food Science And Technology Keywords: amino acids; liver; alcohol
Online: 20 December 2019 (06:44:08 CET)
Excess alcohol consumption is a top risk factor for death and disability. Fatty liver will likely develop and the risk of liver disease increases. We have previously demonstrated that an essential amino acid supplement (EAAS) improved protein synthesis and reduced intrahepatic lipid in the elderly. The purpose of this study was to further evaluate the influence of EAAS on intrahepatic lipid (IHL), body composition, and blood lipids in individuals with mild to moderate alcohol use disorder (AUD). Following consent, determination of eligibility, and medical screening, 25 participants (18 males at 38±15 years/age and 7 females at 34±18 years/age) were enrolled and randomly assigned to one of two dosages: a low dose (LD: 8 grams of EAAS twice/day (BID)) or high dose (HD: 13 grams of EAAS BID). Both groups consumed the supplement for 4 weeks. Pre- and post-EAAS administration, IHL was determined using magnetic resonance imaging/spectroscopy, body composition was analyzed using dual energy x-ray absorptiometry, and blood parameters were measured by LabCorp. T-tests were used for statistical analysis and considered significant at P<0.05. While there was no significant change in IHL in the LD group, there was a significant 23% reduction in IHL in the HD group (p=0.02). Fat mass, lean tissue mass, bone mineral content, and blood lipids were not altered. Post-EAAS phosphatidylethanol was elevated and remained unchanged in LD at 407±141 ng/ml and HD at 429±196 ng/ml, indicating chronic and excess alcohol consumption. Based on these results, we conclude that 13 grams of proprietary EAAS consumed BID lowers IHL in individuals with mild to moderate AUD.
ARTICLE | doi:10.20944/preprints202306.0835.v1
Subject: Biology And Life Sciences, Life Sciences Keywords: aziridinonic radicals; proteinogenic amino acids; synthons
Online: 12 June 2023 (13:05:28 CEST)
This paper represents a thermodynamic and chemical reactivity study regarding the possible formation of four proteinogenic amino acids: glutamic acid, glutamine, lysine and arginine, starting from three synthons: methylene, nitrene and carbon monoxide. All intermediates are specified: neutral molecules and radicals involved in the formation of these four proteinogenic amino acids. The study is based on the synthonic theory of the formation of the first proteinogenic amino acids and their corresponding polypeptides. The thermodynamic quantitative data are obtained from mechanical-quantum calculations mainly by the DFT-B88-LYP methods, DZVP basis set.
REVIEW | doi:10.20944/preprints202012.0220.v1
Subject: Biology And Life Sciences, Anatomy And Physiology Keywords: chromatography; amino acids; fatty acids; pork analysis; adipose tissue; muscle tissue; nutritional factors.
Online: 9 December 2020 (11:14:18 CET)
The increasing demand for high-quality livestock products dictates to develop approaches to assessing the composition of the fatty acids (CFAs) and amino acids (CAAs) in animal tissues. The review considers the following issues: chromatographic methods for the determination of CAAs and CFAs of pig tissues; factors influencing the CAAs and CFAs of pig tissues; methods of regulating CAAs and CFAs of pork using nutritional factors; the effect of CAAs and CFAs on formation of meat properties. The main methods for determining CAAs or CFAs are the ion-exchange or gas chromatography, respectively. The total FA amount and individual FAs have significant effects on the tenderness, taste, color and juiciness of pork meat (due to the different melting points of particular fatty acids, formation of lipid oxidation products during cooking, etc.). Muscle proteins of pigs with regulated fatness differ also in CAAs (decreasing by increase in “pork fat” and decrease in the protein’s amount. The significance of this review is also determined by high popularity of pork in Russia and in a number of other countries of the world.
ARTICLE | doi:10.20944/preprints202309.1648.v1
Subject: Biology And Life Sciences, Horticulture Keywords: cucumber; powdery mildew; infection; DL-3-amino-butyric acid; defense gene
Online: 25 September 2023 (09:31:29 CEST)
Powdery mildew disease, caused by Sphaerotheca fusca, is a major disease affecting cucumbers cultivated in greenhouses. This study was conducted to find defense genes induced by DL-3-amino-butyric acid (BABA) and powdery mildew in cucumber. The 2000 and 5000 mg/L BABA treated cucumber exhibited disease severity of 25% and 5%, respectively, whereas the water treated cucumber leaves were severely infected, with a disease severity of 90%. BABA did not effect spore germination of the powdery mildew pathogen,. showing BABA is not antifungal agent against the pathogen. In quantitative real-time PCR analysis, BABA treated cucumber upregulated transcriptional level of the defense genes CsPAL, CsPR3,CsPR1, CsLOX1, CsLOX23, Cs LecRK6.1, CsWRKY20, and Cupi4 in cucumber to maximum levels at 48 h, whereas CsLecRK6.1 reached maximum expression after 24 h and futher salicylic acid (SA) levels were significantly increased in BABA-treated cucumber plants. In addition, the infected cucumber with powdery mildew enhanced the expression levels from1.6 to 47.3 fold of the defense genes PAL, PR3, PR1, Lox1, Lox 23, LecRK6.1, WRKY20, and Cupi4 compared to heathy cucumber. The results suggests the BABA induced defense response is associated with SA signal pathway-dependent systemic acquired resistance (SAR) in cucumber, which is involved in plant resistance mechanisms.
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: D-amino acids; homochirality; molecular modeling; secondary structure occupancy; stability
Online: 21 January 2021 (12:44:27 CET)
On the primitive Earth, both L- and D-amino acids would have been present. However, only L-amino acids are essential blocks to construct proteins in modern life. To study the relative stability of D-amino acid substituted peptides, a variety of computational methods were applied. Ten prebiotic amino acids (Gly, Ala, Asp, Glu, Ile, Leu, Pro, Ser, Thr, and Val) were previously determined by multiple meteorite, spark discharge, and hydrothermal vent studies. Some previously reported early Earth polypeptide analogs were focused on in this study. Tripeptides composed of only Asp, Ser, and Val exemplified that different positions (i.e., N-terminus, C-terminus, and middle) made a difference in the minimal folding energy of peptides, while the chemical classification of amino acid (hydrophobic, acidic, or hydroxylic) did not show a significant difference. Hierarchical cluster analysis for dipeptides with all possible combinations of the proposed ten prebiotic amino acids and their D-amino acid substituted derivatives generated five clusters. Primordial simple polypeptides were modeled to test the significance of molecular fluctuations, secondary structure occupancies, and folding energy differences based on these clusters. We found peptides with α-helices, long β-sheets, and long loops are usually less sensitive to D-amino acid replacements in comparison to short β-sheets. Intriguingly, amongst 129 D-amino acid residues, mutation sensitivity profiles presented that the ratio of more to less stable residues was about 1. In conclusion, some combinations of a mixture of L- and D-amino acids can potentially act as essential building blocks of life.
ARTICLE | doi:10.20944/preprints202309.0538.v1
Subject: Medicine And Pharmacology, Urology And Nephrology Keywords: Chronic kidney disease; End-stage kidney disease; amino acids; metabolites
Online: 7 September 2023 (11:24:56 CEST)
There is a pressing need for more precise biomarkers of chronic kidney disease (CKD). Plasma samples from 820 subjects [231 with CKD, 325 with end-stage kidney disease (ESKD) and 264 controls] were analyzed by LC-MS/MS to determine a metabolic profile of 28 aminoacids (AA) and biogenic amines to test their value as markers of CKD risk and progression. The Kynurenine/Tryptophan ratio showed the strongest correlation with estimated glomerular filtration rate values (coefficient=-0.731, P<0.0001). Models created with Orthogonal Partial Least Squares-Discriminant Analysis (OPLS-DA) containing the metabolic signature showed high goodness of fit and predictability for controls/CKD (R2X:0.73;R2Y:0.92;Q2:0.92) and lower for CDK/ESKD (R2X:0.56;R2Y:0.59;Q2:0.55). Based on generated VIP scores, the most relevant markers for segregating samples into control/CKD or CKD/ESKD groups were citrulline (1.67) and tryptophan (1.59), respectively. ROC analysis showed that the addition of the metabolic profile to a model including CKD classic risk factors improved AUC from 86.7% (83.6-89.9) to 100% (100-100) for CKD risk (P<0.0001), and from 63.0% (58.2-67.8) to 96.5% (95.3-97.8) for the risk of progression from CKD to ESKD (P<0.0001). Plasma concentrations of AA and related amines may be useful as diagnostic biomarkers of kidney disease, both for CKD risk and for progression of CKD patients to ESKD.
ARTICLE | doi:10.20944/preprints202104.0677.v1
Subject: Chemistry And Materials Science, Analytical Chemistry Keywords: iridium; N-heterocyclic carbene; amino acid; asymmetric transfer hydrogenation
Online: 26 April 2021 (14:16:15 CEST)
A series of chiral complexes of the form Ir(NHC)2(aa)(H)(X) (NHC = N-heterocyclic carbene, aa = chelated amino acid, X = halide) was synthesized by oxidative addition of -amino acids to iridium(I) bis-NHC compounds and screened for asymmetric transfer hydrogenation of ketones. Following optimization of the reaction conditions, NHC, and amino acid ligands, high enantioselectivity was achieved when employing the Ir(IMe)2(l-Pro)(H)(I) catalyst (IMe = 1,3-dimethylimidazol-2-ylidene), which asymmetrically reduces a range of acetophenone derivatives in up to 95% enantiomeric excess.
ARTICLE | doi:10.20944/preprints202208.0088.v1
Subject: Medicine And Pharmacology, Oncology And Oncogenics Keywords: Amino acids; cancer; cancer metabolism; cancer therapy; kidney cancer; renal adenocarcinoma; renal cancer; metastasis; selective amino acid restriction therapy; restriction
Online: 3 August 2022 (11:16:39 CEST)
Targeted therapies with antiangiogenic drugs (e.g., sunitinib) and immune checkpoint inhibitors (e.g., anti-PD-1 antibodies) are the standard of care for patients with metastatic renal cell carcinoma. Although these treatments improve patient survival, they are rarely curative. We previously hypothesized that advanced cancers might be treated without drugs by using artificial diets in which the levels of specific amino acids (AAs) are manipulated. In this work, after showing that AA manipulation induces selective anticancer activity in renal cell carcinoma cells in vitro, we evaluated the anticancer activity of 17 artificial diets in a challenging animal model of renal cell carcinoma. The model was stablished by injecting murine renal cell carcinoma (Renca) cells into the peritoneum of immunocompetent BALB/cAnNRj mice. Mice survival was markedly improved when their normal diet was replaced with our artificial diets. Mice fed a diet lacking six AAs (diet T2) lived longer than mice treated with sunitinib or anti-PD-1 immunotherapy; several animals lived very long or were cured. Controlling the levels of several AAs (e.g., cysteine, methionine and leucine) and lipids was important for the anticancer activity of the diets. Additional studies are needed to further evaluate the therapeutic potential of this simple and inexpensive anticancer strategy.
ARTICLE | doi:10.20944/preprints202310.1155.v2
Subject: Biology And Life Sciences, Food Science And Technology Keywords: Edible insect; lipid classes; index of atherogenicity; index of thrombogenicity; species-specific conversion factor; amino acid scores
Online: 24 October 2023 (08:16:34 CEST)
This study is based on the fatty acid and amino acid profile of 7 edible insect species: Acheta domesticus, Alphitobius diaperinus, Blaptica dubia, Galleria mellonella, Locusta migratoria, Tenebrio molitor and Zophobas morio. The fatty acid distribution within lipid classes (neutral lipids, glycolipids and phospholipids) was studied, while the amino acid profile was used to calculate the species-specific nitrogen-protein conversion factor (Kp). The profiles were used to evaluate the nutritional quality of the lipids and proteins. Oleic acid was the predominant fatty acid in all insects except for A. domesticus, in which a larger percentage of linoleic acid was found. The majority of the lipids were neutral lipids. L. migratoria showed a remarkably high content of α-linolenic acid in its phospholipid fraction, while T. molitor phospholipids were the only fraction in which a measurable amount of docosahexaenoic acid was found. Overall, in most insects, the phospholipid fraction had the highest polyunsaturated fatty acid content compared to the other classes, which may be protective in terms of autoxidative stability. Kp values in the range of 4.17 to 6.43 were obtained. Within the nutritional quality indices, all insects showed healthy fatty acid and high quality amino acid profiles.
ARTICLE | doi:10.20944/preprints202107.0210.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: synthetic biology; genetic parts; kill-switch; growth control; unnatural amino acids; codon reassignment; pyrrolysine
Online: 9 July 2021 (09:42:07 CEST)
We designed a novel growth controller regulated by feeding of an unnatural amino acid, Nε-benzyloxycarbonyl-L-lysine (ZK), using a specific incorporation system at a sense codon. This system is constructed by a pair of modified pyrrolisyl-tRNA synthetase (PylRS) and its cognate tRNA (tRNApyl). Although ZK is non-toxic for normal organisms, the growth of Escherichia coli carrying the ZK incorporation system was inhibited in a ZK concentration-dependent manner without causing rapid bacterial death, presumably due to generation of non-functional or toxic proteins. The extent of growth inhibition strongly depended on the anticodon sequence of the tRNApyl gene. Taking advantage of the low selectivity of PylRS for tRNApyl anticodons, we experimentally determined the most effective anticodon sequence among all 64 nucleotide sequences in the anticodon region of tRNApyl gene. The results suggest that the ZK-regulated growth controller is a simple, target-specific, environmental noise-resistant and titratable system. This technique may be applicable to a wide variety of organisms because the growth inhibitory effects are caused by “informational disturbance”, in which the highly conserved system for transmission of information from DNA to proteins is perturbed.
ARTICLE | doi:10.20944/preprints202309.1099.v1
Subject: Medicine And Pharmacology, Immunology And Allergy Keywords: celiac disease; gluten free diet; amino acids; vitamin A; treatment
Online: 19 September 2023 (03:48:23 CEST)
The amino acids (AAs) and vitamins imbalances are observed in celiac disease (CD). This study evaluated the plasma profile of vitamin A and AAs and the expression level of IL-2, IL-4, IL-10, IL-12 and TGFβ in CD patients. A total of 60 children and adults with CD and 40 healthy controls (HCs) were included. Plasma profile of Vitamin A and AAs and the mRNA expression levels of target genes were assessed. Active adult patients exhibited a decrease in Vitamin A levels (p=0.04) and an increase in IL-2 (p=0.008) and IL-12 (p=0.007) mRNA expression compared to HCs. Treated adult patients showed elevated Serine (p=0.003) and Glycin (p=0.04) levels, as well as increased IL-12 (P<0.0001) mRNA expression, and a decrease in Tryptophan (p=0.04) levels relative to the controls. Additionally, treated adult patients had higher plasma levels of Threonine compared to both active (p=0.04) and control (p=0.02) subjects, and increased mRNA expression of IL-4 (p=0.01) in comparison to active patients. In active children with CD, IL-2 mRNA level was found to be higher than in controls (P<0.0001) and in treated children (p=0.005). Treated children with CD exhibited decreased plasma levels of Tryptophan (p=0.01) and Isoleucine (p=0.01) relative to the controls, and increased mRNA expression of TGFβ (p=0.04) relative to active patients. Managing Retinoic acid levels is crucial to alleviate intestinal inflammation of CD patients. Threonine, tryptophan, and Isoleucine are potential therapeutic options for treating CD, and targeting serine, histidine, tyrosine, and aspartate may hold promise as therapeutic targets for CD patients.
ARTICLE | doi:10.20944/preprints202105.0293.v1
Subject: Chemistry And Materials Science, Biomaterials Keywords: mineralization; polyelectrolyte brushes; poly(amino acids); poly-(α,L-glutamic acid); poly-(α,L-aspartic acid); cellulose; molecular dynamics simulation.
Online: 13 May 2021 (13:09:40 CEST)
We used atomistic molecular dynamics (MD) simulations to study polyelectrolyte brushes based on anionic α-L-glutamic acid and α-L-aspartic acid grafted on cellulose in the presence of divalent CaCl2 salt at different concentrations. The motivation is the search of the ways to control properties such as sorption capacity and the structural response of the brush to multivalent salts. For this detailed understanding of the role of side chain length, chemical structure and their interplay is required. It was found that in the case of glutamic acid oligomers, the longer side chains facilitate attractive interactions with the cellulose surface, which forces the grafted chains to lie down on the surface. The additional methylene group in the side chain enables side chain rotation enhancing this effect. On the other hand, the shorter and more restricted side chains of aspartic acid oligomers prevent attractive interactions to a large degree and push the grafted chains away from the surface. The difference in side chain length also leads to differences in other properties of the brush in divalent salt solutions. At a low grafting density, the longer side chains of glutamic acid allow the adsorbed cations to be spatially distributed inside the brush resulting in a charge inversion. With an increase in grafting density, the difference in the total charge of the aspartic and glutamine brushes disappears, but new structural features appear. The longer sides allow for ion bridging between the grafted chains and the cellulose surface without a significant change in main chain conformation. This leads to the brush structure being less sensitive to changes in salt concentration.
ARTICLE | doi:10.20944/preprints202111.0026.v1
Subject: Medicine And Pharmacology, Oncology And Oncogenics Keywords: TSPO PET; amino acid PET; FET PET; glioma; contrast enhancement; spatial correlation
Online: 1 November 2021 (16:02:58 CET)
In this study dual PET and contrast enhanced MRI were combined to investigate their correlation per voxel in patients at initial diagnosis with suspected glioblastoma. Correlation with contrast enhancement (CE) as an indicator of BBB leakage was further used to evaluate whether PET signal is likely caused by BBB disruption alone, or rather attributable to specific binding after BBB passage. PET images with [18F]GE180 and the amino acid [18F]FET were acquired and normalized to healthy background (TBR). Contrast enhanced images were normalized voxel by voxel with the pre-contrast T1-weighted MRI to generate relative CE values (rCE). Voxel-wise analysis revealed a high PET signal even within the sub-volumes without detectable CE. No to moderate correlation of rCE with TBR voxel-values and a small overlap as well as a larger distance of the hotspots delineated in rCE and TBR-PET images were detected. In contrast, voxel-wise correlation between both PET modalities was strong for most patients and hotspots showed a moderate overlap and distance. The high PET signal in tumor sub-volumes without CE observed in voxel-wise analysis as well as the discordant hotspots emphasize the specificity of the PET signals and the relevance of combined differential information from dual PET and MRI images.
ARTICLE | doi:10.20944/preprints202008.0621.v2
Subject: Biology And Life Sciences, Anatomy And Physiology Keywords: Clustering; Mutation; Amino acid substitution; Structural proteins; Biochemical properties; Functional sub-domains
Online: 4 March 2021 (10:17:15 CET)
SARS-CoV-2 is mutating and creating divergent variants across the world. An in-depth investigation of the amino acid substitution in the genomic signature of SARS-CoV-2 proteins is highly essential for understanding its host adaptation and infection biology. A total of 9587 SARS-CoV-2 structural protein sequences collected from 49 different countries are used to characterize protein-wise variants, substitution pattern (type and location), and major substitution changes. The majority of the substitutions are distinct, occurred mostly in a particular location, and leads to a change in amino acid's biochemical properties. In terms of mutational changes, Envelope (E) and Membrane (M) proteins are relatively stable than Nucleocapsid (N) and Spike (S) proteins. Several co-occurrence substitutions are observed, particularly in S and N proteins. Substitution specific to active sub-domains reveals that Heptapeptide Repeat, Fusion peptides, Transmembrane in S protein, and N-terminal and C-terminal domains in N protein are remarkably mutated, and also found few deleterious mutations in these domains.
ARTICLE | doi:10.20944/preprints201812.0263.v1
Subject: Chemistry And Materials Science, Applied Chemistry Keywords: Amino acid ionic liquid; phase change solvent; high CO2 absorption capacity; mechanism of phase change; recycling ability
Online: 21 December 2018 (15:26:24 CET)
As novel materials for carbon capture, phase change solvents can separate into two immiscible phases during the CO2 capturing procedure under a certain temperature. The solvent systems can significantly decrease the energy consumption since the solvents can be regenerated by only heating the rich-CO2 phase. In this work, amino acid ionic liquids (AAILs) were synthesized using quaternary ammonium salts and amino acids as raw materials, and the aqueous solutions were prepared as novel liquid-solid phase change solvents. The results showed that the solvents had excellent CO2 absorption capacity, and the AAILs functionalized by glycine and tryptophan exhibited significant phase change properties. The mechanism of phase-change of the solvent were mainly due to the lower solubility of the product after reaction between AAILs and CO2. The solvent with tryptophan as anion could be regenerated by only heating the CO2-riched solid phase, which might significantly decrease energy consumption of regeneration. And the absorbent could be reused with the regenerated absorption ratio up to 79%. The solvent system has great potential in industrial application due to the easy operation process and efficient recycling ability.
REVIEW | doi:10.20944/preprints201801.0047.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: antimicrobial; Aplysia; biofilm; chemical defense; Escapin; L–amino acid oxidase
Online: 8 January 2018 (08:29:03 CET)
Many marine animals use chemicals to defend themselves and their eggs from predators. Beyond their ecologically relevant functions, these chemicals may also have properties that make them beneficial for humans, including with biomedical and industrial applications. For example, some chemical defenses are also powerful antimicrobial or anti-tumor agents with relevance to human health and disease. One such chemical defense, Escapin, an L–amino acid oxidase in the defensive ink of the sea hare Aplysia californica, and related proteins have been investigated for their biomedical properties. This review details our current understanding of Escapin’s antimicrobial activity, including the array of chemicals generated by Escapin’s oxidation of its major substrates, L–lysine and L–arginine, and mechanisms underlying these molecules’ bactericidal and bacteriostatic effects on planktonic cells and the prevention of formation and removal of bacterial biofilms. Models of Escapin’s effects are presented, and future directions are proposed.
ARTICLE | doi:10.20944/preprints202305.0222.v1
Subject: Medicine And Pharmacology, Pharmacology And Toxicology Keywords: Amino acid derivatives; Digestive enzymes; Pancreatic lipase; Pancreatic α-Amylase; α-Glucosidase; Metabolic disorders
Online: 4 May 2023 (07:59:29 CEST)
Over the last decades, the increased incidence of metabolic disorders such as type 2 diabetes and obesity has motivated researchers to investigate new enzyme inhibitors. In this study, the inhibitory effects of synthetic amino acid derivatives (PPC80, PPC82, PPC84, PPC89, and PPC101) on the activity of digestive enzymes was assessed by in vitro assays. The inhibitory effect was determined by the inhibition percentage and the 50% inhibitory concentration (IC50), and the mechanism of action was investigated by Lineweaver–Burk plots. PPC80, PPC82, and PPC84 inhibited pancreatic lipase (IC50 of 1.67–10.23 x 10-1 mmol/L). The activity of pancreatic α-amylase was suppressed by PPC80, PPC82, PPC84, PPC89, and PPC101 (IC50 of 1.62–5.19 x 10-1 mmol/L). Finally, PPC84, PPC89, and PPC101 also showed a potent inhibitory effect on α-glucosidase (IC50 of 0.51–3.53 x 10-1 mmol/L). PPC80 and PPC82 followed a non-competitive inhibition mechanism against pancreatic lipase, while PPC84 acted through competitive inhibition. The inhibition of pancreatic α-amylase by the derivatives was non-competitive, as well as for PPC84, PPC89 and PPC101 against α-glucosidase. The results suggest that these synthetic amino acid derivatives have inhibitory potential against digestive enzymes and may be used as therapeutic agents to control metabolic disorders.
ARTICLE | doi:10.20944/preprints202310.0013.v1
Subject: Medicine And Pharmacology, Medicine And Pharmacology Keywords: tumor multidrug resistance; P-glycoprotein; pyxinol amino acid ester derivatives; molecular docking; metabolomics
Online: 1 October 2023 (08:32:50 CEST)
(1) Background: The typical transporter protein, P-glycoprotein (P-gp), has been proven to be associated with multidrug resistance (MDR). Pyxinol and 24S-Pyxinol amino acid ester derivatives had been demonstrated to be promising P-gp inhibitors for reversal of tumor MDR in KBV cells, however, their roles in MDR reversal in other tumor-resistant cells are still unclear. (2) Methods: In the present study, we synthesized 40 amino acid ester derivatives of Pyxinol and 24S-Pyxinol. The MDR reversal effects of these derivatives were evaluated in A549/Tax, MCF-7/ADR, and HCT-8/VCR cells using the CCK-8 assay. Subsequently, western blot assay, intracellular Rhodamine123 (Rh123) accumulation assay and P-gp ATPase activity assay were utilized to investigate the effects of active compound on P-gp. Molecular docking was used to predict the possible binding patterns of active compound to P-gp. Moreover, based on UPLC-Q/TOF-MS cellular metabolomics technology to identify endogenous differential metabolites and metabolic pathways associated with tumor MDR effects of the active compound. (3) Results: The results of the CCK-8 assay showed that compounds 8, 14, 16, 17, 18, 23, 25, 34, 36, 37 exhibited strong MDR reversal effect in A549/Tax, MCF-7/ADR and HCT-8/VCR cells, which were screened by reversal fold (RF) greater than 5. Among them, 10 μM of derivative 37 (new compound) showed the outstanding activity (RF: 15.31) in reversing MDR in A549/Tax cells. Compound 37 could act as a substrate for P-gp and inhibit the efflux function of P-gp by competitively binding to the binding site of antitumor drugs. Meanwhile, the molecular docking results confirmed that compound 37 was identified to under-go high-affinity binding to the drug binding site of P-gp. In addition, 14 endogenous differential metabolites and 6 metabolic pathways involved closely associated with the reversal of tumor MDR effects of compound 37 were identified. (4) Conclusions: Overall, a new candidate compound 37 (24S-3-L-threonyl-Pyxinol) could be provided for reversing tumor MDR by this study.
ARTICLE | doi:10.20944/preprints201911.0216.v1
Subject: Biology And Life Sciences, Animal Science, Veterinary Science And Zoology Keywords: amino acid; digestive enzyme; low protein diet; nitrogen balance; pigs
Online: 19 November 2019 (02:56:38 CET)
This study was conducted to determine the dynamic effects of dietary crude protein (CP) intake on nitrogen (N) balance, ileal amino acid digestibility, and gene expression levels of digestive enzymes at three stages in pigs. In Experiment 1, 18 growing pigs (average body weight (BW) = 9.5 kg) were randomly assigned to one of three treatments (n = 6/treatment group), including normal (20% CP), low (17% CP), and very low (14% CP) protein intake. In Experiment 2, 18 growing pigs (average BW = 30 kg) were allotted randomly to one of three treatments (n = 6/treatment group), including normal (18% CP), low (15% CP), and very low (12% CP) protein intake. In Experiment 3, 18 growing pigs (average BW = 45 kg) were assigned randomly to one of three treatments (n = 6/treatment group), including normal (16% CP), low (13% CP), and very low (10% CP) protein intake. Growing pigs fed the 14% CP and 17% CP diets had lower final BW (P < 0.05) and average daily gain (ADG) (P < 0.05) compared to pigs fed the 20% CP diet. Reducing the dietary CP level from 20 to 14% decreased urinary N excretion by 52.8% (P < 0.001) in Experiment 1. Reducing the dietary CP level from 18 to 12% decreased urinary N excretion by 55.3% (P < 0.001) and reduced fecal N excretion by 34% (P < 0.05) in Experiment 2. Reducing the dietary CP level from 16 to 10% decreased urinary N excretion by 56.4% (P < 0.001) and fecal N excretion by 47.1% (P < 0.001) in Experiment 3. Pigs fed the very low (14%, 12%, and 10% CP) diets showed higher digestibility for CP (P < 0.05), His (P < 0.05), Ile (P < 0.05), Phe (P < 0.05), Thr (P < 0.05), Trp (P < 0.05), Glu (P < 0.05), and Ser (P < 0.05) compared to pigs fed the normal (20%, 18%, and 16% CP) diets among the three experiments. Pigs fed the very low (14%, 12%, and 10% CP) diets showed higher mRNA levels for chymotrypsin C (P < 0.01 in Experiment 1 and 2; P < 0.05 in Experiment 3) compared to pigs fed the normal (20%, 18%, and 16% CP) diets among the three experiments. These results indicated that a reduction in dietary CP by 6% limited the growth performance of growing pigs, and a reduction of dietary CP by 3% supplemented with essential amino acids could reduce the excretion of N into the environment without affecting weight gain.
ARTICLE | doi:10.20944/preprints202311.1841.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: 2D semiconductors; chirality; CdSe nanoplatelets; circular dichroism; amino acids, excitons; ligand exchange, colloidal synthesis
Online: 29 November 2023 (06:11:04 CET)
Chiral semiconductor nanostructures and nanoparticles are promising materials for applications in biological sensing, enantioselective separation, photonics, and spin-polarized devices. Here, we have studied the induction of chirality in atomically thin only 2 monolayers thick CdSe nanoplatelets (NPLs) grown by a colloidal method and exchanged with L-alanine and L-phenylalanine as model thiol-free chiral ligands. We have developed a novel two-step approach to completely exchange the native oleic acid ligands for chiral amino acids at the basal planes of NPLs. We performed an analysis of the optical and chiroptical properties of the chiral CdSe nanoplatelets with amino acids, which was supplemented by an analysis of the composition and coordination of ligands. After the exchange, the nanoplatelets retain HH, LH and SO exciton absorbance and bright HH exciton luminescence. Capping with thiol-free enantiomer amino acid ligands induce pronounced chirality of excitons in the nanoplatelets, as proven by circular dichroism spectroscopy, with high dissymmetry g-factor up to 3.4 × 10−3 achieved for HH excitons in the case of L-phenylalanine.
ARTICLE | doi:10.20944/preprints202307.0765.v1
Subject: Medicine And Pharmacology, Pharmacy Keywords: 4-amino-7-chloroquinoline; 1,3,4-oxadiazole; anthranilic acid; synthesis; quorum sensing; anti-biofilm; P. aeruginosa; PQS
Online: 12 July 2023 (21:25:14 CEST)
Inhibition of quorum sensing (QS)-dependent biofilm formation and virulence is extensively investigated as a novel approach to combat bacterial pathogens by impeding their ability to cause antibiotic-tolerant diseases. Such strategies are considered a promising alternative to conventional antibacterial therapy since interrupting the central cell-to-cell communication system imposes less selective pressure on the target pathogen. In this study, novel hybrid compounds composed of anthranilic acids substituted with halogens at different positions of the phenyl ring, and 4-(2-aminoethyl/4-aminobuthyl)amino-7-chloroquinoline linked via 1,3,4-oxadiazole were synthesized using standard procedures. Their anti-QS activities were evaluated using Chromobacterium violaceum ATCC31532 (anti-biofilm and bactericidal activities) and Pseudomonas aeruginosa PAO1 (anti-biofilm/-virulence activities). The results showed that compounds 15–19 and 23 inhibited the production of violacein, the QS-inducible pigment, in C. violaceum to a similar extent as the model QS inhibitor - quercetin (83.5–90%). Compound 15 exhibited the strongest effect on P. aeruginosa in the anti-biofilm screening, reducing its ability to form biofilm by almost 50%, while compounds 16 and 19 were able to reduce the biofilm formation by approximately 30%. However, compound 23 did not demonstrate significant anti-biofilm activity and only inhibited pyocyanin production in P. aeruginosa. In conclusion, this study suggests that 1,3,4-oxadiazoles 15, 16, and 19 are the most promising compounds for future research as novel QS inhibitors against Gram-negative bacteria equipped with different QS signaling pathways.
ARTICLE | doi:10.20944/preprints202307.0838.v1
Subject: Medicine And Pharmacology, Endocrinology And Metabolism Keywords: Assisted reproduction technology; follicular fluid; metabolomics; insulin resistance; amino acid profile; predictive value
Online: 12 July 2023 (11:14:29 CEST)
The global prevalence of insulin resistance (IR) is increasing continuously, influencing metabolic parameters and fertility as well. The metabolic changes due to IR can alter the molecular composition of plasma and other body fluids. Follicular fluid (FF) is derived mainly from plasma, and it is a critical microenvironment for the developing oocytes. It contains various metabolites and amino acids, and the quality of the oocytes is linked at least partially to amino acid metabolism. Our goal was to determine quantitatively the amino acid (AA) profile of FF in IVF patients and to compare IR and non-insulin resistance (NIR) groups to investigate the AA changes in their FF. By UHPLC-based method we quantified the main 20 amino acids from human FF samples in the IR and NIR groups. Several amino acids (aspartate, glycine, glutamate, and cysteine) differed significantly (p<0.05 or less) between the two groups. The most significant alterations between the IR and NIR groups were related to the glutathione metabolic pathway involving glycine, serine, and threonine. Since insulin resistance alters the amino acid composition of the FF, the oocytes may undergo metabolism-induced changes resulting in poor oocyte quality and less fertility in the insulin resistance groups.
REVIEW | doi:10.20944/preprints202306.2170.v1
Subject: Medicine And Pharmacology, Neuroscience And Neurology Keywords: N-acetylcysteine; amino acid supplements; L-arginine; Duchenne muscular dystrophy; mdx mouse; osmolytes; supportive therapy; taurine
Online: 30 June 2023 (07:13:00 CEST)
Duchenne muscular dystrophy (DMD), the severest form of muscular dystrophy, is characterized by progressive muscle weakness with fatal outcome most often before the fourth decade of life. Despite recent addition of molecular treatments, DMD remains a disease without a cure, and the need persists for the development of supportive therapies aimed to help improve patients’ quality of life. This review focusses on the therapeutical potential of amino acid and derivative supplements, summarizing results obtained in preclinical studies in the murine disease model. Several promising compounds have come forward, with L-arginine, N-acetylcysteine and taurine featuring among the most intensively investigated. Beneficial effects include improved muscle function and reduced muscle fiber necrosis and reduced inflammatory and oxidative damage to muscle tissues, however mild side effects have also surfaced. In order to identify amino acid formulae that are safe and of true benefit to DMD patients, more explorative, placebo-controlled and long-term clinical trials need to be conducted, documenting therapeutic outcomes.
COMMUNICATION | doi:10.20944/preprints202109.0457.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: counter-selection; unnatural amino acids; pyrrolysyl tRNA synthetase; genetic code expansion; sence codon reassignment; plasmid curing
Online: 27 September 2021 (17:09:00 CEST)
A protocol was designed for plasmid curing using a novel counter-selectable marker, named pylSZK-pylT, in Escherichia coli. The pylSZK-pylT marker consists of the archaeal pyrrolysyl-tRNA synthetase (PylRS) and its cognate tRNA (tRNApyl) with modification, and incorporates an unnatural amino acid (Uaa), Nε-benzyloxycarbonyl-l-lysine (ZK), at a sense codon in ribosomally synthesized proteins, resulting in bacterial growth inhibition or killing. Plasmid curing is performed by exerting toxicity on pylSZK-pylT located on the target plasmid, and selecting only proliferative bacteria. All tested bacteria obtained using this protocol had lost the target plasmid (64/64), suggesting that plasmid curing was successful. Next, we attempted to exchange plasmids with the identical replication origin and an antibiotic resistance gene without plasmid curing using a modified protocol, assuming substitution of plasmids complementing genomic essential genes. All randomly selected bacteria after screening had only the substitute plasmid and no target plasmid (25/25), suggesting that plasmid exchange was also accomplished. Counter-selectable markers based on PylRS-tRNApyl, such as pylSZK-pylT, may be scalable in application due to their independence from the host genotype, applicability to a wide range of species, and high tunability due to the freedom of choice of target codons and Uaa’s to be incorporated.
ARTICLE | doi:10.20944/preprints201911.0189.v1
Subject: Biology And Life Sciences, Food Science And Technology Keywords: protein; plant-based protein; whey protein; essential amino acids; leucine, healthy men
Online: 16 November 2019 (00:58:01 CET)
This study assessed bio-equivalence of high-quality, plant-based protein blends versus Whey Protein Isolate (WPI) in healthy, resistance-trained men. The primary endpoint was incremental area under the curve (iAUC) of blood essential Amino Acids (eAAs) 4 hours after consumption of each product. Cmax and Tmax of blood leucine were secondary outcomes. Subjects (n=18) consumed three plant-based protein blends and WPI (control). Analysis of Variance model was used to assess for bio-equivalence of total sum of blood eAA concentrations. The total blood eAA iAUC ratios of the three blends were: [90% CI]: #1: 0.66 [0.58-0.76]; #2: 0.71 [0.62-0.82]; #3: 0.60 [0.52-0.69], not completely within the pre-defined equivalence range [0.80-1.25], indicative of 30-40% lower iAUC versus WPI. Leucine Cmax of the three blends was not equivalent to WPI, #1: 0.70 [0.67-0.73]; #2: 0.72 [0.68-0.75]; #3: 0.65 [0.62 – 0.68], indicative of a 28-35% lower response. Leucine Tmax for two blends were similar to WPI (#1: 0.94 [0.73-1.18]; #2: 1.56 [1.28-1.92]; #3: 1.19 [0.95-1.48]). The plant-based protein blends were not bio-equivalent. However, blood leucine kinetic data across the blends approximately doubled from fasting concentrations whereas blood Tmax data across two blends was similar to WPI. This suggests evidence of rapid hyperleucinemia, which correlates with a protein’s anabolic potential.
ARTICLE | doi:10.20944/preprints202105.0021.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: PRLTS3; Release of mtDNA and mtRNA; cGAS-STING; Leukodystrophy; Ataxia; Mitochondrial Amino Acid tRNA Synthetases; TWINKLE; POLG; MTRNR1
Online: 4 May 2021 (14:08:18 CEST)
Mitochondrial dysfunctions, e.g. abnormal handling of mitochondrial DNA in TFAM mutants or in altered mitophagy, activate innate immunity. Recent reports also showed that deletion of mitochondrial matrix peptidase ClpP in mice transcriptionally upregulates inflammatory factors. Here, we studied ClpP-null mouse brain at two ages and embryonal fibroblasts, to identify which signaling pathways are responsible, employing mass spectrometry, immunoblots, and reverse transcriptase polymerase chain reaction. Anomalies in the mitochondrial unfolded protein responses pathway were prominent for the co-chaperone DNAJA3, and for its known interactor STAT1. Their mitochondrial dysregulation affected also their extra-mitochondrial abundance, as possible innate immune modulators. Increased expression was observed not only for the transcription factors Stat1/2, but also for two interferon-stimulated genes (Ifi44, Gbp3). Inflammatory responses were strongest for RLR pattern recognition receptors (Ddx58, Ifih1, Oasl2, Trim25) and several cytosolic nucleic acid sensors (Ifit1, Ifit3, Oas1b, Ifi204, Mnda). They can be explained by the accumulation of mitoribosomes and mitochondrial nucleoids in ClpP-null cells, which may act as damage-associated molecular patterns. The consistent dysregulation of these factors from early age might influence also human Perrault syndrome, where ClpP loss-of-function leads to early infertility and deafness, with subsequent widespread neurodegeneration.
ARTICLE | doi:10.20944/preprints202309.1349.v1
Subject: Engineering, Chemical Engineering Keywords: CO2 Capture; Metal Organic Framework (MOF); Ionic Liquid; Amino Acid Ionic Liquid (AAILs); Task-Specific Ionic Liquid (TSIL); MOF-177
Online: 20 September 2023 (10:40:47 CEST)
This study presents the encapsulation of two amino acid-based ionic liquids (AAILs), 1-Ethyl-3-methylimidazolium glycine [Emim][Gly] and 1-Ethyl-3-methylimidazolium alanine [Emim][Ala], in a highly porous metal organic framework (MOF-177), to generate state-of-the-art composites for post-combustion CO2 capture. The thermogravimetric analysis (TGA) demonstrated a successful encapsulation of the AAILs, consequently dramatically reducing the composites' surface area and pore volume. Both [Emim] [Gly]@MOF-177 and [Emim][Ala]@MOF-177 had close to 3 times the CO2 uptake of MOF-177 at 20 wt.% loading, 0.2 bar, and 303 K. Additionally, 20-[Emim][Gly]@MOF-177 and 20-[Emim] [Ala]@MOF-177 enhanced their CO2/N2 selectivity from 5 (pristine MOF-177) to 13 and 11, respectively.
ARTICLE | doi:10.20944/preprints201804.0073.v1
Subject: Chemistry And Materials Science, Food Chemistry Keywords: Rossa da inverno sel. Rojo Duro onion cultivar; geographical origin; amino acids content; HPLC analysis; statistical evaluations; food traceability
Online: 6 April 2018 (09:04:47 CEST)
In the frame of a broader project, we were interested at comparing the amino acid profile in a specific variety of onion, Rossa da inverno sel. Rojo Duro, produced in two different Italian sites: Cannara (Umbria region) and Imola (Emilia Romagna region). In both places, onions were cultivated and harvested in the same way, and irrigated by water sprinkler method. A further group of Cannara onions, growth by microirrigation, was also evaluated. After the extraction of free amino acid mixture from onion samples, an ion-pairing RP-HPLC method allowed the separation and the evaporative light scattering detection of almost all underivatized proteinogenic amino acids. However, only the peaks corresponding to Leu, Phe, Trp, were present in all the investigated samples and unaffected from matrix interfering peaks. The application of the beeswarm/box plots with the ANOVA/TukeyHSD statistical approach revealed a content of Leu and Phe markedly influenced by the geographical origin of the onions, while not by the irrigation procedure. The developed HPLC method was validated in terms of specificity, linearity, LOD and LOQ, accuracy and precision, before the quantitative assay of Leu, Phe and Trp in the onion samples. Although further studies are necessary, these preliminary findings can represent a good starting point for considering the quantity of specific amino acids in the Rossa da inverno sel. Rojo Duro variety as a fingerprint of its geographical origin. In principle, the developed approach might be applied to other onion varieties, thus contributing to their characterization and traceability, also contributing to limit commercial frauds.
REVIEW | doi:10.20944/preprints202312.0631.v1
Subject: Medicine And Pharmacology, Clinical Medicine Keywords: intestinal failure, parenteral nutrition, home parenteral nutrition, fish oil based intravenous lipid emulsion, crystalline amino acids solution, multi-chamber bags
Online: 8 December 2023 (15:19:06 CET)
Intestinal failure (IF) is characterized by a critical reduction of functional gut mass below the minimum needed for optimal growth in children. It requires parenteral nutrition (PN) and home-PN (HPN) which is challenging in terms of meeting nutritional needs according to age, growth velocity, clinical situation, and rapid changes in fluid and electrolyte requirements. Due to these complex requirements, age-adapted multi-chamber bags (MCBs) are important additions to the nutrition armamentarium. The launch of composite fish oil (FO)-containing intravenous lipid emulsions (ILEs) heralded the development of MCBs containing these ILEs in combination with a crystalline amino acids solution (CAAS) adapted for pediatric use. The safety and efficacy of lipid and amino acid components in this context have been widely documented in numerous published studies. This manuscript includes a review of the articles published in PubMed, Embase, and Google Scholar until June 2022, exploring studies in the age groups from term infants to children and adolescents. Preterm infants with their highly specific demands are not included. It aims to offer an overview of the clinical experience regarding the use of a composite FO-based ILE and a specific CAAS developed
ARTICLE | doi:10.20944/preprints202206.0369.v1
Online: 28 June 2022 (03:32:19 CEST)
We studied surface enhanced Raman spectra of amino acids D-alanine and DL-serine and their mixture on silver nanoisland films (SNF), immersed in phosphate buffer saline solution at millimolar amino acid concentrations. It is shown that the spectra from the amino acid solutions differ from the reference spectra for microcrystallites due to electrostatic orientation of amino acid zwitterions by the metal nanoisland film. Moreover, non-additive peaks are observed in the spectrum of the mixture of amino acids adsorbed on SNF, which means that intermolecular interactions between adsorbed amino acids are very significant. The results indicate the need for a thorough analysis of the Raman spectra from amino acid solutions in the presence of a nanostructured metal surface, and may also be of interest for studying molecular properties and intermolecular interactions.
ARTICLE | doi:10.20944/preprints202111.0406.v1
Online: 22 November 2021 (14:22:59 CET)
We research the interaction between six representative carbon-based nanoparticles (CBNs) and 20 standard amino acids through all-atom molecular dynamics simulations. The six carbon-based nanoparticles are fullerene(C60), CNT55L3, CNT1010L3, CNT1515L3, CNT2020L3, and two-dimensional-graphene(Graphene33). Their curvatures decrease sequentially, and all of CNT are single-walled carbon nanotubes. We have observed that as the curvature of CBNs decreases, the adsorption effect of 20 amino acids with them has an increasing trend. In addition, we also used multi-dimensional clustering to analyze the adsorption effects of 20 amino acids on six carbon-based nanoparticles. We observed that the π-π interaction still plays an extremely important role in the adsorption of amino acids on carbon-based nanoparticles. Individual long-chain amino acids and “Benzene-like” Pro also have a strong adsorption effect with carbon-based nanoparticles.
ARTICLE | doi:10.20944/preprints202309.0187.v1
Subject: Medicine And Pharmacology, Pharmacology And Toxicology Keywords: integrated stress response; amino acid; PERK; cyclin-dependent kinases; cell cycle; amino acid transport
Online: 5 September 2023 (05:00:11 CEST)
The integrated stress response is a signaling network comprised of four branches, each of which senses different cellular stressors, converging on the phosphorylation of eIF2α to depress global translation and initiate recovery. One of these branches is composed of GCN2, which senses cellular amino acid insufficiency and participates in the maintenance of amino acid homeostasis. Previous studies have shown that GCN2 is a viable cancer target when amino acid stress is provoked by inhibiting an additional target. In this light, we screened a combination of drugs to identify biologically active compounds which synergize with the GCN2 inhibitor TAP20. First, a panel of 25 compounds was assayed in six cancer cell lines for drug sensitivity. Each compound was then combined with TAP20 at concentrations below their IC50, and the impact on cell growth was assessed. Selected strongly synergistic combinations were further characterised using synergy analyses and matrix-dependent invasion assays. Inhibitors of proteostasis, of the MEK-ERK pathway and pan-CDK inhibitors flavopiridol and seliciclib were found to potently synergize with TAP20 in two of the tested cell lines. Among their common CDK targets is CDK7, which was selectively targeted with THZ-1 and found to synergize with TAP20. Finally, these combinations were found to be partially synergistic when assessed using matrix-dependent invasion assays. However, we found that TAP20 alone was sufficient to restrict invasion at concentrations well below its growth-inhibitory IC50. We conclude that GCN2 can be targeted for treating cancers by polytherapy or even monotherapy.
REVIEW | doi:10.20944/preprints202308.1370.v1
Subject: Public Health And Healthcare, Primary Health Care Keywords: gucagon; glucose; lipid; amino acid; hyperglucagonemia
Online: 21 August 2023 (03:07:14 CEST)
In the context of type 2 diabetes (T2DM), fasting and postprandial hyperglucagonemia have long been linked to the disease's development and progression. However, recent studies have brought to light the positive impact of glucagon-agonists on lipid metabolism and energy homeostasis. This review delves into the intricate relationship and underlying mechanisms between glucagon and nutrient composition, which may hold promise in devising novel therapeutic approaches for T2DM management.
REVIEW | doi:10.20944/preprints202007.0698.v1
Subject: Medicine And Pharmacology, Oncology And Oncogenics Keywords: cancer metabolism; amino acids; oncogenic therapeutics
Online: 29 July 2020 (12:35:37 CEST)
Amino acid metabolism promotes cancer cell proliferation and survival by supporting building block synthesis, producing reducing agents to mitigate oxidative stress, and generating immunosuppressive metabolites for immune evasion. Malignant cells rewire amino acid metabolism to maximize their access to nutrients. Amino acid transporter expression is upregulated to acquire amino acids from the extracellular environment. Under nutrient depleted conditions, macropinocytosis can be activated where proteins from the extracellular environment are engulfed and degraded into the constituent amino acids. The demand for non-essential amino acids (NEAAs) can be met through de novo synthesis pathways. Cancer cells can alter various signaling pathways to boost amino acid usage for the generation of nucleotides, reactive oxygen species (ROS) scavenging molecules and oncometabolites. The importance of amino acid metabolism in cancer proliferation makes it a potential target for therapeutic intervention, including via small molecules and antibodies. In this review, we will delineate the targets related to amino acid metabolism and promising therapeutic approaches.
ARTICLE | doi:10.20944/preprints202002.0284.v1
Subject: Biology And Life Sciences, Anatomy And Physiology Keywords: amino acids; protein kinetics; fatty acids
Online: 20 February 2020 (05:27:15 CET)
Wild game consumption has been associated with health benefits, but the influence on protein metabolism remains unknown. We compared the feeding-induced response to 2 oz of free-range reindeer (FR) versus commercial beef (CB) using stable isotope methodology. Seven male and female participants (age: 38±12 years; body mass index: 24±3 kg/m2) completed two studies using a randomized, crossover design in which they ingested 2 oz of FR or CB. L-[ring 2H5]phenylalanine & L-[ring 2H2]tyrosine were delivered via primed, continuous intravenous infusion. Blood samples were collected during the basal period and following consumption of FR or CB. Feeding-induced changes in whole body protein synthesis (PS), protein breakdown (PB), and net protein balance (NB) were determined via analysis of plasma samples for phenyalanine and tyrosine enrichment by gas chromatography mass spectrometry; plasma essential amino acid concentrations were determined by liquid chromatography-electrospray ionization-mass spectrometry. Plasma post-prandial essential amino acid (EAA) concentrations were higher with the ingestion of FR compared to CB (P=0.02). The acute feeding-induced response in PS was not different in either trial, but PB was reduced with the ingestion of FR compared to CB (P<0.0001). The difference in PB contributed to a superior level of NB (P<0.0001). When protein kinetics were normalized relative to the amino acids ingested, PB/EAAs and total amino acids ingested were reduced (P<0.01 and 0.001, respectively) in FR compared to CB; contributing to greater NB/total amino acid ingested (P<0.0001) between FR and CB. We conclude that the nutrient profiles of FR may have a more favorable benefit on protein metabolism compared to CB. These data support the potential health benefits of wild game in the preservation of whole-body protein.
COMMUNICATION | doi:10.20944/preprints202304.0068.v1
Subject: Biology And Life Sciences, Life Sciences Keywords: cancer; amino acids; colon; nitrogen; diet; mice
Online: 5 April 2023 (15:45:18 CEST)
Abstract: Cancer cells are originated by normal cells and with those share the need to be fed. Metabolic reprogramming in cancer cells is not yet fully understood although there is a vast literature suggesting that huge amounts of both energy and substrates are require for synthesis of components of new neoplastic cells so that any macronutrient may be efficiently utilized. Recently, in vitro data show that EAA supplementation promoted colon cancer cells apoptosis by enhanced autophagy. Therefore, in this study we tested in vivo the effects of matched macronutrients standard laboratory diet (control) versus EAA rich modified diet (EAArmd) in mice injected with colon cancer cells. Results of the first set of 12 animals, 6 controls and 6 EAArmd-fed, showed that controls mice develop cancer volume cancers 5 times larger and heavier than EAArmd-fed. If confirmed, these results would open new scenarios for the cancer integrate therapies.
COMMUNICATION | doi:10.20944/preprints202303.0269.v1
Subject: Medicine And Pharmacology, Oncology And Oncogenics Keywords: cancer; amino acids; colon; nitrogen, diet, mice
Online: 15 March 2023 (03:12:31 CET)
Cancer cells are originated by normal cells and with those share the need to be fed. Metabolic reprogramming in cancer cells is not yet fully understood, and there is a vast literature suggesting that any macronutrient may be efficiently utilized by cancer for duplication purposes. Metabolic hyperactivity of cancer and continuous duplication requires huge amounts of both energy and substrates for syntheses of components of new cells, and the modifications of metabolism induced by cancer cells to survive and grow damaging lethally, the whole organism. In rodents, we have recently observed that by modifying diet in a way not existent in nature, changing radically the ratios among essential and non-essential amino acids (AA) (usually less than 0.9), largely increasing essential-AA (EAA) percentages, lifespans increased. In vitro, EAA supplementation promoted colon cancer cells (CT116) apoptosis by enhanced autophagy. Therefore, we tested in mice if injection of colon cancer cells would have been followed by unvaried development of cancer volumes in animals fed with standard laboratory diet (controls) versus EAA rich modified diets (EAAmd). Both diets perfectly matched the same total macronutrients and micronutrients contents; only quality of nitrogen was radically different. Results of the first set of 8 animals, 4 controls and 4 EAAmd-fed, showed that controls develop cancers near 5 times larger and heavier than EAAmd-fed (P<0,002) on the same time. We discuss which epigenetic modifications would be involved and worth to be studied, and what kind of scenarios those preliminary findings, if confirmed, would open.
ARTICLE | doi:10.20944/preprints202311.0184.v1
Subject: Biology And Life Sciences, Horticulture Keywords: peach; amino acid; drought stress; osmotic; physiological index
Online: 3 November 2023 (01:32:00 CET)
Peach (L.) is a kind of fruit tree with considerable economic and nutritional significance. However, it shows a high sensitivity to drought stress, which has a profound impact on its growth. L-methionine (MET) and L-proline (PRO) are two amino acids synthesized by plants, which play an important role in abiotic stress response. However, their exact mechanism of action remains elusive. Through physiological analysis, MET (500ppm) and PRO (500ppm) treatments can effectively reduce the adverse effects of drought stress on the growth of peach seedlings. Studies have shown that amino acid (AA) can effectively inhibit the stomatal opening of plant leaves and increase the photosynthetic rate. In addition, the application of MET or PRO promoted the accumulation of carbohydrates in leaf tissues, increased intracellular water potential (24%, 24%), reduced osmotic potential (21%, 24%), and alleviated membrane damage caused by drought. Using Evans Blue, nitroblue tetrazolium (NBT) and DAB (3, 3-diaminobenzidine) staining experiments, We confirmed that the increase in antioxidant enzyme activity in leaves may be due to the removal of reactive oxygen species (ROS) in vivo, namely the downregulation of malondialdehyde (18%, 19%) ，peroxidase (50%, 5%) and superoxide dismutase (12%, 14%) activities. In addition, the application of exogenous amino acids also improved the root morphology and vitality of peach seedlings, which was conducive to absorbing external buffer substances and alleviating drought stress. In summary, the application of exogenous amino acids can effectively alleviate the effects of drought stress on plants and reduce the harm.
ARTICLE | doi:10.20944/preprints202310.1772.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: amaranth; OMET; bioactive compounds; amino acids; minerals; PCA
Online: 27 October 2023 (10:04:12 CEST)
Organic Medium Enclosed Trough (OMET) is a new non-drainable growing technique. The study envisioned to investigate the interactive effects of OMET and Amaranth species vari-ation on some growth attributes, bioactive compounds and nutrients. Three Amaranth species: A. caudatus, A. cruentus and A. tricolor were grown in an OMET and non-OMET growing conditions. Growth attributes, irrigation water, bioactive compounds and nutri-ents were determined. Non-OMET and A. cruentus showed the highest total phenolics and flavonols followed by A. caudatus and A. tricolor, whilst tannins were predominant in A. caudatus followed by A. cruentus and A. tricolor. The use of unsupervised PCA showed major metabolic variation based on Amaranth species and the use of supervised OPLS-DA showed clear metabolic variation based on OMET and non-OMET. OMET and A. cruentus showed the highest plant height, stem diameter, biomass, and some nutrients (%protein, Ca, P, Cu, Se, Zn), followed by A. caudatus based only on growth and biomass, and A. tricol-or based only on some nutrients (Mg, K, Mn, and Fe). The use OMET system on A. cruentus and A. tricolor can be recommended to mitigate climate change effects on nutritional com-position using low irrigation water.
ARTICLE | doi:10.20944/preprints202307.0287.v1
Subject: Chemistry And Materials Science, Organic Chemistry Keywords: chiral amplification/enrichment; enantiomer; prebiotic era; amino acid
Online: 5 July 2023 (11:23:21 CEST)
A general method is presented that permits enantiomers, originally present in a low enantiomeric excess (%ee1), to accumulate in a high %ee (%ee2) without a chiral source present. An equation was derived that demonstrates the final %ee2 of any unreacted chiral starting material will become higher when that starting material has reacted to generate an additional chiral center, hence forming two sets of diastereomeric enantiomeric products. Importantly, chiral amplification factor (multiples), %ee2/%ee1, depends on the yield of this reaction (p), which exhibits a nonlinear increase in amplification as p approaches 100%. This process is inevitable. It represents a possible route by which small initial %ee1 values of prebiotic molecules could have been raised to high %ee2 contents during the pre-evolution of life period on Earth, without the need for an added chiral source to be present. This predicted behavior was then experimentally verified in Pictet-Spengler reactions of L-tryptophane methyl ester (L-TME) samples present in low enantiomeric excess (%ee1) with biacetyl or oxaldehyde (model reactions) run to various yields. Each reaction generates stereoisomer products, and chiral amplification of the L-TME’s initial %ee1 values to higher %ee2 values occurs in the unreacted (recovered) L-TME. Repeated cycles of these reactions create very high L-TME %ee values. Self-cyclodimerization of low %ee1 L-amino acids with their D-enantiomers to generate L,L-, D,D- and L,D-cyclic products were computationally studied, leading to the same conclusion. Small %ee1 values are enhanced to larger %ee2 in the unreacted starting materials.
ARTICLE | doi:10.20944/preprints202305.1771.v1
Subject: Biology And Life Sciences, Food Science And Technology Keywords: Silage; corn; wheat; microbial inoculum; amino acids; digestibility
Online: 25 May 2023 (08:40:24 CEST)
Wheat and corn silages are widely used as ruminant feed in Israel due to their availability and cost-effectiveness. To ensure long-term preservation without compromising nutritional quality, effective methods must be employed. Inclusion of additives during harvest and ensiling can enhance efficiency and address preservation challenges. In the current study, the effects of microbial inoculum (MI) and urea on the chemical composition, amino acid profiles, aerobic stability, and in vitro digestibility of wheat and corn silages were investigated. Samples of wheat and corn were subjected to four treatments: control, MI, Urea, and a combination of MI+Urea. The treatments were ensiled in anaerobic conditions and opened after 1, 7, 14, or 28 days. Results showed that additives improved the quality parameters of wheat and corn silages. The inclusion of MI produced the most aerobically stable silages. The inclusion of urea in silages deteriorated aerobic stability. Additives improved in vitro cell wall carbohydrates digestibility in both silages and was the best when MI was combined with urea. These results imply additives could be incorporated in silages to enhance their nutritional value, aerobic stability and digestibility. Nonetheless, increased CP content with additives was not accompanied with parallel increase in amino acids content in corn silage.
ARTICLE | doi:10.20944/preprints202304.0918.v1
Subject: Biology And Life Sciences, Virology Keywords: BCMV; genome; proteome; amino acid substitutions; novel host
Online: 25 April 2023 (10:16:22 CEST)
Bean common mosaic virus from the genus Potyvirus has a wide range of hosts and a very negative impact on cultivated crops from the genus Phaseolus. The risk of viral infection of economically important crops increases even if the carriers of the virus are related plant species growing on agroecological interfaces. Such plant species have emerged as new hosts for BCMV, usually harboring novel genetic variants of the virus. A novel genetic variant of BCMV was isolated from a symptomatic crownvetch plant, where the presence of this virus was confirmed by Western-blotting analysis and by amino acid identities in peptide fragments of CI, HC-pro, and CP proteins using the nanoLC-ESI-Q-TOF. The novel BCMV SVK isolate differed from the most genetically similar one in 0.91% of nucleotides and 1.55% of amino acids. The highest number of amino acid substitutions (8.8% of amino acids) was in the P1 protein, followed by CP (2.44% of amino acids). Minor substitutions were in Hc-pro, CI, and Nib proteins. The symptomatic crownvetch plant was confirmed as a new host and carrier of the novel BCMV isolate.
ARTICLE | doi:10.20944/preprints202304.0797.v1
Subject: Biology And Life Sciences, Life Sciences Keywords: Heart failure; Malnutrition; Exercise; Amino-acids; mTOR; Deptor
Online: 23 April 2023 (08:45:26 CEST)
Malnutrition, clinically evident primarily with sarcopenia, is present in more than 50% of CHF patients and is an independent factor of morbidity and mortality. Several pathophysiological mechanisms, such as reduced appetite, metabolic imbalance and altered protein synthesis/degradation rate, due to the blood increase of hypercatabolic molecules, have been proposed to explain this phenomenon. Nutritional supplementation with proteins, amino acids and vitamins have all been used to treat malnutrition, acting through mTOR stimulation. However, the success and efficacy of these procedures are often contradictory and not conclusive. Interestingly, data on exercise training show that exercise reduces mortality and increase functional capacity, although it also increases energy expenditure and nitrogen providing substrate needs. Therefore, this paper discusses the molecular mechanisms of integrated nutritional approaches that would stimulate metabolic anabolic pathways. Pivotal in our opinion, is the relationship between exercise and Deptor, a subunit of the mTOR complex. Consequently, we propose a combination of personalized and integrate nutritional supplementation as well as exercise to treat malnutrition and related anthropometric and functional CHF-related disorders.
REVIEW | doi:10.20944/preprints202112.0331.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: Genetic code expansion; unnatural amino acid; fluorescence imaging
Online: 21 December 2021 (12:42:35 CET)
Genetic code expansion has emerged as an enabling tool to provide insight into functions of understudied proteinogenic species such as small proteins and peptides, and to probe protein biophysics in the cellular context. Here we discuss recent technical advances and applications of genetic code expansion in cellular imaging of complex mammalian protein species, along with considerations and challenges upon using the method.
ARTICLE | doi:10.20944/preprints202003.0089.v1
Subject: Chemistry And Materials Science, Materials Science And Technology Keywords: sol-gel; amino-functionalized silica; catalyst; activity; hydrogenation
Online: 5 March 2020 (12:05:00 CET)
The article describes synthesis of aminoorgano-functionalized silica as a perspective material for catalysis application. The amino groups have electron donor properties valuable for metal chemical state of palladium. So presence of electron donor groups is important for increasing of catalysts stability. The research is devoted to investigation of silica amino-modified support influence on activity and stability of palladium species in 4-nitroaniline hydrogenation process. A series of catalysts with different supports such as SiO2, SiO2-C3H6-NH2 (amino-functionalized silica), γ-Al2O3 and activated carbon were studied. The catalytic activity was studied in the hydrogenation of 4-nitroaniline to 1,4-phenylenediamine. The catalysts were characterized by scanning electron microscopy, transmission electron microscopy, x-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and pulse chemisorption of hydrogen. The 5 wt. % Pd/SiO2-C3H6-NH2 catalyst exhibited the highest catalytic activity for 4-nitroaniline hydrogenation with 100% conversion and 99% selectivity with respect to 1,4-phenylenediamine.
REVIEW | doi:10.20944/preprints201809.0459.v1
Subject: Medicine And Pharmacology, Dietetics And Nutrition Keywords: Nutrition; Amino acids; Leukocytes; Skeletal muscle; Gut; Liver.
Online: 24 September 2018 (13:20:58 CEST)
Glutamine is the most abundant and versatile amino acid in the body. In health and disease, the rate of glutamine consumption by immune cells is similar or greater than glucose. For instance, in vitro and in vivo studies have determined that glutamine is an essential nutrient for lymphocyte proliferation and cytokine production, macrophage phagocytic plus secretory activities and neutrophil bacterial killing. Glutamine release to the circulation and availability is mainly controlled by key metabolic organs, such as the gut, liver and skeletal muscles. During catabolic/hypercatabolic situations glutamine can become essential for metabolic function, but its availability may be compromised due to impairment of homeostasis in the inter-tissue metabolism of amino acids. For this reason, glutamine is currently part of clinical nutrition supplementation protocols and/or recommended for immune suppressed individuals. However, in a wide range of catabolic/hypercatabolic situations (e.g. ill/critically ill, post-trauma, sepsis, exhausted athletes) it is currently difficult to determine whether glutamine parenteral or enteral supplementation should be recommended based on the amino acid plasma concentration (glutaminemia). Although the beneficial immune based effects of glutamine supplementation is already established, many questions and evidence for positive in vivo outcomes still remain to be presented. Therefore, this paper provides an integrated review on how glutamine metabolism in key organs is important to cells of the immune system. We also discuss glutamine metabolism, action and important issues related to the effects of glutamine supplementation in catabolic situations.
ARTICLE | doi:10.20944/preprints202308.2171.v1
Subject: Chemistry And Materials Science, Biomaterials Keywords: 1-(2-((3-amino-2-hydroxypropyl)amino)ethyl)-1'-ethyl-[4,4'-bipyridine]-1,1'-diium; Iron Polymer-Complex; MTT; A375 cells.
Online: 31 August 2023 (10:43:55 CEST)
In the present study, linear novel polymer poly(1-(2-((3-amino-2-hydroxypropyl)amino)ethyl)-1'-ethyl-[4,4'-bipyridine]-1,1'-di-ium) (poly(AHAEBD)) and its complex with iron (ΙΙΙ) ([Fe(poly(AHAEBD)2].Na3) were synthesized and then their anticancer effects on A375 human malignant melanoma cells line were evaluated. The structure of the synthesized compounds was confirmed using Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (1HNMR), field emission scanning electron microscopy (FE-SEM), X-ray energy diffraction analysis (EDS) and gel permeation chromatography (GPC). Also, the cytotoxicity of cisplatin as a reference, on A375 melanoma cell line was tested. The IC50 of polymer-complex [Fe(poly(AHAEBD)2].Na3 (0.71 µg/mL), cisplatin (4.58 µg/mL) and poly(AHAEBD) (1.73 µg/mL) were obtained. Our results revealed that the polymer-complex [Fe(poly(AHAEBD)2].Na3 exhibited better performance compared to cisplatin. Furthermore, the coordination with iron (III) enhanced the cytotoxicity levels of poly(AHAEBD). According to these findings, the synthesized polymer-complex demonstrates remarkable potential as an anti-cancer agent. This study could provide the basis for future research focused on employing this new polymer-complex for in vivo testing, highlighting its potential for therapeutic applications.
ARTICLE | doi:10.20944/preprints202301.0376.v1
Subject: Medicine And Pharmacology, Oncology And Oncogenics Keywords: sulphur amino acids; anticancer activity; metastasis; cancer metabolism; colorectal cancer; ovari-an cancer; renal cancer; methionine; cysteine; taurine; amino acids
Online: 22 January 2023 (04:09:19 CET)
The sulfur-containing amino acids methionine (Met), cysteine (Cys) and taurine (Tau) are common dietary constituents with important cellular roles. Met restriction is already known to exert in vivo anticancer activity. However, since Met is a precursor of Cys, and Cys produces Tau, the role of Cys and Tau in the anticancer activity of Met-restricted diets is poorly understood. In this work, we screened the in vivo anticancer activity of several Met-deficient artificial diets supplemented with Cys, Tau or both. Diet B1 (6% casein, 2.5% leucine, 0.2% Cys and 1% lipids) and diet B2B (6% casein, 5% glutamine, 2.5% leucine, 0.2% Tau and 1% lipids) showed the highest activity and were selected for further studies. Both diets induced a marked anticancer activity in two animal models of metastatic colon cancer, which were established by injecting CT26.WT murine colon cancer cells in the tail vein or peritoneum of immunocompetent BALB/cAnNRj mice. Diets B1 and B2B also increased the survival of mice with disseminated ovarian cancer (intraperitoneal ID8 Tp53 -/- cells in C57BL/6JRj mice) and renal cell carcinoma (intraperitoneal Renca cells in BALB/cAnNRj mice). The high activity of diet B1 in mice with metastatic colon cancer may be useful in colon cancer therapy.
ARTICLE | doi:10.20944/preprints202306.1763.v1
Subject: Chemistry And Materials Science, Analytical Chemistry Keywords: isothermal titration calorimetry; racemization heat; dilution heat; amino acids
Online: 26 June 2023 (09:12:29 CEST)
Chiral interactions play a crucial role in both chemistry and biology. Understanding the behavior of chiral molecules and their interactions with other molecules is essential, and chiral interactions in solutions are particularly important for studying chiral compounds. Chirality influences the physical and chemical properties of molecules, including solubility, reactivity, and biological activity. In this work, we used Isothermal Titration Calorimetry (ITC), a powerful technique for studying molecular interactions, including chiral interactions in solutions. We conducted a series of ITC measurements to investigate the heat of dilution and the heat of racemization of several amino acids (Asn, His, Ser, Ala, Met, and Phe). We also performed ITC measurements under different solute concentrations and temperatures to examine the effects of these parameters on chiral interactions, as well as the heat of dilution and racemization. The results of our measurements indicated that the heat of dilution, specifically the interactions between the solvent (water) and solute (chiral molecules), had a significant impact compared to the chiral interactions in the solution, which were found to be negligible. This suggests that the interactions between chiral molecules and the solvent play a more dominant role in determining the overall behavior and properties of the system. By studying chiral interactions in solutions, we can gain valuable insights into the behavior of chiral compounds, which can have implications in various fields, including drug design, chemical synthesis, and biological processes.
Subject: Physical Sciences, Acoustics Keywords: clams; physiological status; stress; cold chain; free amino acid
Online: 30 June 2021 (11:58:19 CEST)
With the extension of the post-catch circulation time, a series of changes had taken place in the soft tissue of the live clams, resulting in the decline of its quality. This study investigated the quality changes of clams (Ruditapes philippinarum) in cold chain and was mainly focused on the rehydration process, which included gradient heating rehydration (GR) and sudden heating rehydration (SR). It was found that the GR had a better effect on the quality of clams than the SR. The GR stage clams showed a higher survival rate, glycogen content and adenylate energy charge (A.E.C) value than the SR stage clams. Conversely, the GR stage clams showed lower lactic acid content and K-value than the SR stage clams. The results indicated that the gradient heating rehydration was beneficial to the quality of clams. The transportation and rehydration strategies benefited both producers and shellfish merchants to save total cost.
COMMUNICATION | doi:10.20944/preprints202012.0365.v1
Subject: Chemistry And Materials Science, Analytical Chemistry Keywords: corrosion; amino acids; inhibitors; steel; iron; Monte Carlo simulation
Online: 15 December 2020 (10:09:29 CET)
This research evaluates the inhibitory effect of L-amino acids (AAs) with different side chain lengths on Fe surface implementing Monte Carlo (MC) simulation. A quantitative and qualitative description of the adsorption behavior of AAs on the iron surface has been carried out. Calculations have shown that the absolute values of the adsorption energy of L-amino acids increase with side chain prolongation; they are also determined by the presence of heteroatoms. AAs from nonpolar and basic groups have the best adsorption ability to the iron surface, which indicates their highest inhibitory efficiency according to the results of MC simulation.
ARTICLE | doi:10.20944/preprints202004.0137.v1
Subject: Biology And Life Sciences, Virology Keywords: SARS-CoV-2; genomes; nucleotide; amino-acid; mutations; replacements
Online: 9 April 2020 (05:56:35 CEST)
Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), a novel evolutionarily divergent RNA virus etiological agent of COVID-19, is responsible for present devastating pandemic respiratory illness. To explore the genomic signatures, we comprehensively analyzed 2,492 complete and/or near-complete genome sequences of SARS-CoV-2 strains reported from across the globe to the GISAID database up to 30 March 2020. Genome-wide annotations revealed 1,407 nucleotide-level mutations at different positions throughout the entire genome of SARS-CoV-2. Moreover, nucleotide deletion analysis found nine deletions throughout the genome, including in polyprotein (n=6), ORF10 (n=1) and 3´-UTR (n=2). Evidence from the systematic gene-level mutational and protein profile analyses revealed a large number of amino acid (aa) substitutions (n=722), making the viral proteins heterogeneous. Notably, residues of receptor-binding domain (RBD) having crucial interactions with angiotensin-converting enzyme 2 (ACE2), and cross-reacting neutralizing antibody were found to be conserved among the analyzed SARS-CoV-2 strains, except for replacement of Lysine with Arginine at 378 position of the cryptic epitope of a Shanghai isolate, hCoV-19/Shanghai/SH0007/2020 (EPI_ISL_416320). Our method of genome annotation is a promising tool for monitoring and tracking the epidemic, the associated genetic variants, and their implications for the development of effective control and prophylaxis strategy.
REVIEW | doi:10.20944/preprints201805.0145.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: carbonic anhydrase, enzyme inhibition, metalloenzymes, amino acid, glaucoma, tumors
Online: 9 May 2018 (13:55:15 CEST)
Carbonic Anhydrases (CAs) are a superfamily of metalloenzymes widespread in all life kingdoms, classified into seven genetically different families (α-θ). These enzymes catalyse the reversible hydration of carbonic anhydride (CO2), generating bicarbonate (HCO3-) and protons (H+). Fifteen isoforms of human CA (hCA I-XV) have been isolated, their presence being fundamental for the regulation of many physiological processes. In addition, overexpression of some isoforms has been associated with the outbreak or the progression of several diseases. For this reason, for a long time CA inhibitors (CAIs) are used in the control of glaucoma and as diuretics. Furthermore, the search for new potential CAIs for other pharmacological applications is a very active field. Amino acids constitute the smallest fundamental monomers of protein and, due to their useful bivalent chemical properties, are widely used in organic chemistry. Both proteinogenic and non-proteinogenic amino acids have been extensively used to synthesize CAIs. This article provides an overview of the different strategies that have been used to design new CAIs containing amino acids, and how these bivalent molecules influence the properties of the inhibitors.
ARTICLE | doi:10.20944/preprints201708.0021.v1
Subject: Chemistry And Materials Science, Surfaces, Coatings And Films Keywords: 3-((2-chlorobenzylidene)amino)coumarin; corrosion inhibitor; damage reduction
Online: 7 August 2017 (10:51:42 CEST)
New corrosion inhibitor derived from coumarin-3-amine namely 3-((2-chlorobenzylidene)amino)coumarin was synthesized and characterized by CHN elemental analysis in addition to Fourier transform infrared and nuclear magnetic resonance techniques. The anti-corrosion ability of 3-((2-chlorobenzylidene)amino)coumarin to inhibit the impacts of corrosion has been demonstrated and damage reduction of the mild steel also. 3-((2-chlorobenzylidene)amino)coumarin, has been employed as a good corrosion inhibitor for mild steel in HCL solution. The efficiency of the inhibition was figured according to weight loss method and it was 74.6%.
ARTICLE | doi:10.20944/preprints202311.0543.v1
Subject: Biology And Life Sciences, Aquatic Science Keywords: protein sources; gut health; microbiome; Oreochromis niloticus; amino acid intake
Online: 8 November 2023 (11:36:54 CET)
Dietary protein quality plays a key role in maintaining intestinal mucosal integrity, but also modulates the growth of luminal microorganisms. This work assessed the effect of dietary protein sources on the performance, gut morphology, and microbiome in Nile tilapia. Four isonitrogenous and isolipidic diets comprising equivalent amounts of the protein supply derived from either PLANT, ANIMAL, INSECT, or MICROBIAL (bacterial biomass) sources were fed to triplicate groups of fish (IBW: 12 g) during 46 days. Fish fed ANIMAL and MICROBIAL diets showed significantly higher growth than those fed the PLANT and INSECT diets (P < 0.05). Relative abundance at the phylum level shows Bacteroidetes, Fusobacteria and Proteobacteria as more abundant phyla in tilapia’s intestine, while Cetobacterium is the most representative genera in all treatments. Interesting patterns were observed in the correlation between amino acid intake and genus and species abundance. Metabolism prediction analysis showed that microbial amine and polyamine degradation pathways are modulated depending on diets. In conclusion, different protein sources interfere directly with the cross-talk of bacteria pathways and amino acid intake.
COMMUNICATION | doi:10.20944/preprints202305.1782.v1
Subject: Biology And Life Sciences, Virology Keywords: COVID-19; microscale thermophoresis; SLC6A20 amino acid transporter; antiviral agents
Online: 25 May 2023 (09:33:29 CEST)
As the COVID-19 pandemic progresses, new variants of SARS-CoV-2 continue to emerge. This underscores the need to develop optimized tools to study such variants, as well as new coronaviruses that may arise in the future, and to use them for antiviral drug development. Here we introduce microscale thermophoresis (MST) as a reliable and versatile tool for coronavirus research, which we demonstrate through three different applications described in this report: 1) binding of the SARS-CoV-2 spike receptor binding domain (RBD) to peptides as a strategy to prevent virus entry, 2) binding of the RBD to the viral receptor ACE2, and 3) binding of the RBD to ACE2 in complex with the amino acid transporter SLC6A20/SIT1 or its allelic variant rs61731475 (p.Ile529Val). Our results demonstrate that MST is a highly precise approach to study protein-protein and/or protein-ligand interactions in coronavirus research, making it an ideal tool for studying viral variants and developing antiviral agents. The ability to measure interactions with proteins in their near-native plasma membrane environment is a unique advantage of the MST assay over other available binding assays.
ARTICLE | doi:10.20944/preprints202209.0133.v1
Subject: Medicine And Pharmacology, Oncology And Oncogenics Keywords: amino acid PET; FET PET; glioma; FET negative; photopenic; radiomics
Online: 9 September 2022 (09:31:45 CEST)
46 patients with a newly diagnosed, histologically verified glioma that was visually classified as [18F]FET-negative were included. Tumor volumes were defined using routine T2/FLAIR MRI data and applied to extract information from dynamic [18F]FET PET data, i.e. early and late tu-mor-to-background (TBR5-15, TBR20-40) images and time-to-peak (TTP) images. Radiomic features of healthy background were calculated from the tumor volume-of-interest mirrored to the con-tralateral hemisphere. Differences between tumor and healthy tissue features were compared us-ing Wilcoxon test. Additionally, the ability to distinguish tumor from healthy tissue was assessed using logistic regression. 5 % of features derived from TBR20-40 images were significantly differ-ent; 16 % of features derived from TBR5-15 images and 69 % of features derived from TTP images. The high number of significantly different features derived from TTP images was even found in isometabolic gliomas (after exclusion of photopenic gliomas) with visually normal [18F]FET up-take in static images. However, the differences did not reach satisfactory predictability for ma-chine learning based identification of tumor tissue. In conclusion, radiomic features derived from dynamic [18F]FET PET data may extract additional information even in [18F]FET-negative glio-mas, which should be investigated in larger cohorts and correlated with histological and out-come features in future studies.
ARTICLE | doi:10.20944/preprints202105.0034.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: Amino Acid Neurotransmitter; Glutamate; Gaba; Pentylenetetrazole; Vitamin B1; Vitamin B6
Online: 5 May 2021 (11:10:42 CEST)
Disturbed metabolism of vitamins B1 or B6, which are essential for neurotransmitters homeostasis, may cause epilepsy. Our study aims at revealing therapeutic potential of vitamins B1 and B6 in epilepsy by estimating effects of their combined administration on a seizure and its consequences in rats subjected to pentylenetetrazole (PTZ). The PTZ dose dependence of a seizure and its parameters according to Racine’s scale along with delayed physiological and biochemical consequences next day after the seizure are assessed regarding sexual dimorphism in epilepsy. PTZ sensitivity is stronger in the female than male rats. Next day after a seizure, gender differences in behavior and brain biochemistry arise. The induced gender differences in anxiety, exploratory and locomotor activity correspond to disappearance of gender differences in the brain GABA, aspartate, alanine and serine, with appearance of those in glutamate, glutamine and tyrosine. PTZ decreases the brain malate dehydrogenase activity, glutamine and urea in the males, and phenylalanine in the females. Administration of vitamins B1 and B6 24 h before PTZ delays a seizure in female rats only. This desensitization is not observed at short intervals (0.5-2 h) between the vitamins and PTZ administration. With the increasing interval, the pyridoxal kinase (PLK) activity in the female brain decreases, suggesting that the PLK downregulation by vitamins contributes to the desensitization. Delayed effects of vitamins and/or PTZ are mostly gender-specific and interacting. Our findings on the gender differences in sensitivity to epileptogenic factors, action of vitamins B1/B6 and associated biochemical events have medical implications.
ARTICLE | doi:10.20944/preprints202004.0034.v2
Subject: Computer Science And Mathematics, Applied Mathematics Keywords: Shannon entropy; Hurst exponent; Amino acid; Frequency distribution; \& SARS-CoV2
Online: 6 April 2020 (14:00:15 CEST)
The world is now undergoing through a global emergency due to COVID-19 which needs immediate remedies in order to strengthen the healthcare facility to save the nations. Looking towards to the remedies, research on different aspects including the genomic and proteomic level characterizations of the SARS-CoV2 are necessarily important. In this present study, the spatial representation/composition of twenty amino acids across the primary protein sequences of SARS-CoV2 have been looked into through different parameters viz. Shannon entropy, Hurst exponent in order to fetch the autocorrelation and amount of information over the spatial representations. Also frequency distribution of each of the amino acids over the protein sequences have been chalked out.
ARTICLE | doi:10.20944/preprints201905.0301.v1
Subject: Biology And Life Sciences, Horticulture Keywords: amino acid metabolism; carvacrol; metabolomics data; oxidative stress; Penicillium digitatum
Online: 24 May 2019 (14:33:50 CEST)
Carvacrol has long been studied for its natural antifungal potential and food preservative. But the exact mode of its action remained highly complex as a general, but especially for Penicillium digitatum (P. digitatum) largely remained unexplored. Herein, a 1H-NMR-based metabolomic technique was used to investigate the antifungal mechanism of carvacrol. The metabolomic profiling data showed that alanine, aspartate, glutamate and glutathione metabolism were imbalanced in the fungal hyphae. A strong positive correlation was seen between aspartate, glutamate, alanine and glutamine, while negative correlation among glutathione and lactate. These metabolic changes revealed that carvacrol-induced oxidative stress had disturbed the energy production and amino acid metabolism of P. digitatum. Current study will improve the understanding of the metabolic changes posed by plant-based fungicides in order to control citrus fruit green mold caused by P. digitatum. Moreover, the study will provided certain experimental and theoretical basis for the development of novel citrus fruit preservatives.
REVIEW | doi:10.20944/preprints201808.0503.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: HMB; Branched-chain amino acid; Strength training; Sports nutrition; Inflammation.
Online: 29 August 2018 (14:12:18 CEST)
β-hydroxy β-methylbutyrate (HMB) is a bioactive metabolite formed from breakdown of the branched-chain amino acid leucine. Given the popularity of HMB supplements among different athletes, specifically, those who engage in regular resistance training, this review was performed to summarize current literature on some aspects of HMB supplementation that have received less attention. Because of the small number of published studies, it has not been possible to conclude the exact effects of HMB on cardiovascular parameters, oxidative stress and inflammatory markers. Thus, the interpretation of outcomes should be taken cautiously. However, the data presented here suggest that acute HMB supplementation may attenuate pro-inflammatory response following an intense resistance exercise in athletes. Also, the available findings collectively indicate that chronic HMB consumption in conjunction with resistance training has no more adaptive advantages associated with decreasing cardiovascular risk factors and oxidative stress markers. Taken together, there is clearly a need for further well-designed, longer duration studies to support these findings and determine whether HMB supplementation affects the adaptations induced by resistance training associated with body’s inflammatory condition, antioxidative defense system, and cardiovascular risk factors in humans.
REVIEW | doi:10.20944/preprints202305.2152.v1
Subject: Medicine And Pharmacology, Oncology And Oncogenics Keywords: cancer metabolism; anticancer activity; artificial diets; in vivo; mice; essential amino acids; non-essential amino acids; restriction; leucine; methionine; cysteine; arginine; serine; glutamine; asparagine
Online: 30 May 2023 (13:24:11 CEST)
Cancer cells cannot proliferate and survive unless they obtain sufficient levels of the 20 proteinogenic amino acids (AAs). Unlike normal cells, cancer cells have genetic and metabolic alterations that may limit their capacity to obtain adequate levels of the 20 AAs under challenging metabolic environments. However, since normal diets provide all AAs at relatively constant levels and ratios, these potentially lethal genetic and metabolic defects are eventually harmless to cancer cells. If we temporarily replace the normal diet of cancer patients with artificial diets in which the levels of specific AAs are manipulated, cancer cells may be unable to proliferate and survive. This article reviews in vivo studies that have evaluated the antitumor activity of diets restricted or supplemented with the 20 proteinogenic AAs, individually and in combinations. It also reviews our recent studies that show that manipulating the levels of several AAs simultaneously can lead to marked survival improvements in mice with metastatic cancers.
ARTICLE | doi:10.20944/preprints202311.0979.v1
Subject: Environmental And Earth Sciences, Space And Planetary Science Keywords: Mars Global Simulant; Stress tolerance; Antioxidant; Amino acids; Proline; Sugar classes
Online: 15 November 2023 (09:54:16 CET)
Growing food autonomously on Mars is challenging due to the Martian soil's low nutrient content and high salinity. Understanding how plants adapt and evaluating their nutritional attributes are pivotal for sustained Mars missions. This research delved into the regeneration, stress tolerance, and dietary metrics of sweet potato (Ipomoea batatas) across different Mars Global Simulant (MGS-1) concentrations (0, 25, 50, and 75%). In our greenhouse experiment, 75% MGS-1 concentration most significantly inhibited sweet potato growth, storage root biomass, and chlorophyll content. This concentration also elevated plant tissues' H2O2, proline, and ascorbic acid levels. Higher MGS-1 exposures (50 and 75%) notably boosted vital amino acids and sugar groups in the plant's storage roots. Yet, increased MGS-1 concentrations notably diminished the total C: N ratio and elemental composition in both vines and storage roots. In summary, sweet potato exhibited optimal growth, antioxidant properties, yield, and nutrient profiles at 25% MGS-1 exposure, compared to higher concentrations. This study underscores the need for future interventions, like nutrient enhancement and controlled metal accessibility, to render it a suitable plant for space-based studies.
ARTICLE | doi:10.20944/preprints202309.1313.v1
Subject: Biology And Life Sciences, Food Science And Technology Keywords: Aquatic weeds; Edible paper; Proximate composition; Biofunctional compounds; Minerals; Amino acids
Online: 20 September 2023 (03:03:39 CEST)
Three edible aquatic weeds, helencha (Enhydra fluctuans), malancha (Alternanthera philoxeroides), and kalmi (Ipomoea aquatica), were used to produce edible paper sheets. The composition of the raw and paper sheet samples was analyzed, including proximate composition, amino acid content, minerals and heavy metal contents, and bioactive compounds. The dried raw and paper sheets showed similar proximate composition, with carbohydrates being the highest (50.38-64.63%), followed by crude protein (15.25-19.13%), ash (9.30-15.88%), and lipid (1.549-3.43%). The weeds and paper sheets were rich in essential minerals like Na, Ca, Zn, and Fe. Acceptable levels of heavy metals, including Ni, Pb, and Cu, were found. The paper sheets contained seven essential and eight non-essential amino acids. A. philoxeroides sheets showed the highest amino acid content (16146.81mg/100g), while I. aquatica showed the lowest (13118.67 mg/100g). The aquatic weeds paper sheets were rich in containing bioactive compounds and the number in E. fluctuans, A. philoxeroides, and I. aquatica paper sheets were 31, 33, and 40, respectively. There were no significant changes in the nutritional content of aquatic weeds in paper sheet form compared to the raw weeds which suggests promising prospects for the production and consumption as a source of nutrition and bioactive compounds.
REVIEW | doi:10.20944/preprints202309.0213.v1
Subject: Biology And Life Sciences, Aging Keywords: aging; amino acids; antioxidant; arginine; nitric oxide; oxidative stress; protein; peptide
Online: 6 September 2023 (14:47:08 CEST)
The master molecular regulators and mechanisms determining longevity and health span include nitric oxide (NO) and superoxide anion radicals (SOR). L-arginine, the NO synthase (NOS) substrate, can restore a healthy ratio between the dangerous SOR and the protective NO radical to promote healthy aging. Antioxidant supplementation orchestrates protection against oxidative stress and damage—L-arginine and antioxidants such as vitamin C increase NO production and bioavailability. Uncoupling of NO generation with the appearance of SOR can be induced by asymmetric dimethylarginine (ADMA). L-arginine can displace ADMA from the site of NO formation if sufficient amounts of the amino acid are available. Antioxidants such as ascorbic acids can scavenge SOR and increase the bioavailability of NO. The topics of this review are the complex interactions of antioxidant agents with L-arginine, which determine NO bioactivity and protection against age-related degeneration.
REVIEW | doi:10.20944/preprints202309.0090.v1
Subject: Biology And Life Sciences, Aging Keywords: aging; amino acids; antioxidant; arginine; nitric oxide; oxidative stress; protein; peptide
Online: 1 September 2023 (16:25:31 CEST)
The master molecular regulators and mechanisms determining longevity and health span include nitric oxide (NO) and superoxide anion radicals (SOR). L-arginine, the NO synthase (NOS) substrate, can restore a healthy ratio between the dangerous SOR and the protective NO radical to promote healthy aging. Antioxidant supplementation orchestrates protection against oxidative stress and damage—L-arginine and antioxidants such as vitamin C increase NO production and bioavailability. Uncoupling of NO generation with the appearance of SOR can be induced by asymmetric dimethylarginine (ADMA). L-arginine can displace ADMA from the site of NO formation if sufficient amounts of the amino acid are available. Antioxidants such as ascorbic acids can scavenge SOR and increase the bioavailability of NO. The topics of this review are the complex interactions of antioxidant agents with L-arginine, which determine NO bioactivity and protection against age-related degeneration.
ARTICLE | doi:10.20944/preprints202304.1179.v1
Subject: Chemistry And Materials Science, Physical Chemistry Keywords: ion-exchange membrane; neutralization dialysis; modelling; phenylalanine losses; amino acid; demineralization
Online: 28 April 2023 (11:37:33 CEST)
A non-steady state mathematical model of amino acid (phenylalanine (Phe)) and mineral salt (NaCl) solution separation by neutralization dialysis (ND) carried out in a batch mode is proposed. The model takes into account the characteristics of membranes (thickness, ion-exchange capacity and conductivity) and solutions (concentration, composition), as well as the flow rate of the solution in the dialyzer compartments. As compared to previously developed models, the new one considers the local equilibrium of Phe protolysis reactions in solutions and membranes and, also, the transport of all the phenylalanine forms (zwitterionic, positively and negatively charged) through membranes. A series of experiments on ND demineralization of NaCl and Phe mixed solution was carried out. In order to minimize Phe losses, the solution pH in the desalination compartment was controlled by changing the concentrations of the solutions in the acid and alkali compartments of the ND cell. The validity of the model was verified by comparison of simulated and experimental time dependencies of solution electric conductivity and pH, as well as the concentration of Na+, Cl– ions and Phe species in the desalination compartment. Based on the simulation results, the role of Phe transport mechanisms in the losses of this amino acid during ND was discussed.
ARTICLE | doi:10.20944/preprints202304.0609.v1
Subject: Medicine And Pharmacology, Pharmacy Keywords: American cranberry (Oxycoccus macrocarpus); leaves; extract; modification; amino acid; hepatoprotective activity.
Online: 20 April 2023 (05:28:46 CEST)
The liver performs a fundamental role in the regulation of diverse physiological processes. Despite enormous advances in modern medicine, there are no completely effective drugs that stimulate hepatic function, offer complete protection to the organ, or aid in regenerating hepatic cells. Thus, it is necessary to identify alternative plant-origin pharmaceuticals more effective and less toxic for the treatment of hepatic diseases. The aim of this research was to establish the chemical composition of the American cranberry (Oxycoccus macrocarpus) leaves extract and its aminoacids preparations as well as their hepatoprotective activity. 19 phenolic compounds (8 flavonoids (flavones and flavonols), 4 anthocyanins, 2 catechins, and 3 hydroxycinnamic acids) and main amino acids (valine, arginine, glycine, histidine, aspartic acid, and taurine) were identified and quantified in the American cranberry (O. macrocarpus) leaves extract and its 7 aminoacids preparations. The therapeutic and prophylactic consumption of the American cranberry leaves extracts led to a decrease in the intensity of the lipid peroxidation process compared to the control pathology group in the experiment of acute toxic damage to the liver by tetrachloromethane on rats. The most pronounced hepatoprotective activity was established for the American cranberry leaves extracts’ preparations with arginine and valine.
REVIEW | doi:10.20944/preprints202012.0696.v1
Subject: Medicine And Pharmacology, Immunology And Allergy Keywords: microalgae; carotenoids; chlorophylls; lipids; mycosporin-like amino acids; antioxidants; UV-screen
Online: 28 December 2020 (12:15:07 CET)
A prominent feature of stress-tolerant microalgae is their versatile metabolism allowing then to synthesize a broad spectrum of molecules with beneficial effects on many aspects of human body functioning. This is in line with the current understanding that many stress-induced deleterious processes in the human body and in photosynthetic cell are mediated by the same mechanisms such as free-radical attacks and lipid peroxidation. These related risks are kept at bay by optical screening of harmful UV, enzymatic ROS elimination systems, and potent low-molecular antioxidants. Microalgae synthesize a broad spectrum of compounds exerting antioxidant and/or UV-absorbing properties. In microalgae, they increase stress-resilience of these organisms. In human body, they exhibit photoprotective, antiaging, and sunscreen activities. Therefore, these algal metabolites were recognized as promising ingredients for innovative cosmetics and cosmeceutical formulations. Ever increasing effort is being invested into the search for new natural biologically active substances from microalgae. This trend is also fueled by the growing demand for natural raw materials for food, pharmaceuticals and cosmetology associated with the global transition to a "greener" lifestyle. Here, we review the currently accumulated knowledge about the main groups of cosmeceutical compounds from microalgae.
SHORT NOTE | doi:10.20944/preprints202006.0225.v1
Subject: Biology And Life Sciences, Virology Keywords: SARS-CoV-2; web application; virus genome; lineage assignment; amino acids
Online: 18 June 2020 (06:24:20 CEST)
Summary CoV-GLUE is an online web application for the interpretation and analysis of SARS-CoV-2 virus genome sequences, with a focus on amino acid sequence variation. It is based on the GLUE data-centric bioinformatics environment and provides a browsable database of amino acid replacements and coding region indels that have been observed in sequences from the pandemic. Users may also analyse their own SARS-CoV-2 sequences by submitting them to the web application to receive an interactive report containing visualisations of phylogenetic classification and highlighting genomic variation of potentially high impact, for example linked to primer mismatches.Availability and implementation Available at http://cov-glue.cvr.gla.ac.uk. Implemented using GLUE, an open source framework for the development of virus sequence data resources. Contact email@example.com
SHORT NOTE | doi:10.20944/preprints201911.0318.v4
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: protein sequencing; single molecule; nanopore; tRNA; amino acyl tRNA synthetase; codon; optical tag
Online: 18 February 2020 (11:50:29 CET)
Single molecule de novo protein sequencing based on the 'superspecificity' of amino-acyl tRNA synthetases (aaRS) is proposed. An unfolded protein molecule is threaded through a nanopore in an electrolytic cell (e-cell) to expose the terminal residue in the e-cell's trans chamber. After the residue is cleaved with an exopeptidase, a set of tRNAs, their aaRSs, and ATP are added to trans. An aaRS charges a cognate tRNA molecule with the residue. The charged tRNA (along with the other reactants) is transferred to an extended e-cell with N (20 ≤ N ≤ 61) pores in N individual cis chambers and a single trans chamber. Each pore holds an RNA molecule ending in a unique codon that is exposed in trans. The charged tRNA's anticodon base-pairs with the terminal codon of an RNA. If tRNAs and residues are fluorescently tagged with two different colors, the residue can be identified from the observed position of the resulting color pair. As charging is 'superspecific' identification is unambiguous. The protein molecule in the first e-cell is advanced by one residue and the process repeated. In this approach there is no need for precise pore current or optical intensity measurements. Potential implementation issues are discussed. Other possibilities, including one in which the terminal residue is cleaved after charging, are also examined.
REVIEW | doi:10.20944/preprints201810.0428.v1
Subject: Medicine And Pharmacology, Oncology And Oncogenics Keywords: amino acids, cancer, energy metabolism, autophagy, apoptosis, glutamine, diabetes type 2.
Online: 18 October 2018 (16:45:01 CEST)
Production of energy is a main task of cancer cells metabolism, since costs of duplicating are enormous. Although energy is derived in cells by dismantling carbon to carbon bonds of any macronutrient, cancer nutritional needs for energetic purposes have been studied primarily as dependent on glycolysis. Since the end of the last century, awareness of dependence of cancer metabolism on amino acids not only for protein syntheses but also for matching energy needs has grown. The roles of specific amino acids, like glutamine, glycine and serine have been explored in different experimental conditions and reviewed. Moreover, there are epidemiological evidences that some amino acids used as supplement for therapeutic reasons (the branched chain ones) may reduce incidence of liver cancer, and some molecular mechanism has been proposed as functional to their protective action. On the contrary, metabolic signature of some pathology connected with increased risk of cancer, like prolonged hyperinsulinemia in insulin resistant patients, is signed by plasma elevated levels of the same branched chain amino acids, posing puzzling questions to clinicians. Most recently, peculiar formulations of amino acids, deeply different if compared to amino acids compositions normally present in foods, have shown the power to master epigenetics slowing growth or driving cancer cells to apoptotic death, while being even beneficial for normal cells and for animals health and life span. In this review, we will analyze and try to disentangle some of the many knots dealing with complexities of amino acids biology and linked to cancer metabolism.
ARTICLE | doi:10.20944/preprints201709.0082.v1
Subject: Medicine And Pharmacology, Dietetics And Nutrition Keywords: tyrosine; dose-response; aging; working memory; plasma amino acids; catecholamines; dopamine
Online: 18 September 2017 (15:48:07 CEST)
The effects of tyrosine on plasma response and cognition in aging are unknown. We assessed the dose-dependent response to tyrosine administration in older adults in both plasma tyrosine concentrations and working memory performance. In this double blind randomized cross-over trial 17 older adults (aged 60-75 years) received a single administration of 100, 150 or 200 mg/kg body weight of tyrosine. For comparison, 17 young adults (aged 18-35 years) received a dose of 150 mg/kg body weight of tyrosine. Tyrosine plasma concentrations were determined before and 90, 120, 150, 180, 210 and 240 minutes after tyrosine intake. Working memory was assessed using the N-back task at 90 minutes after tyrosine administration. Older adults showed a dose-dependent increase in plasma tyrosine concentrations (p<.001), and the plasma response was higher than for young adults with the same dose (p<.001). Load-dependent working memory performance decreased with higher doses of tyrosine (p=.048), especially in older adults with greater dose-dependent plasma tyrosine responses (p=.035). Our results show an age-related increase in plasma tyrosine response, which was associated with a dose-dependent decline in cognitive functioning in older adults.
REVIEW | doi:10.20944/preprints201609.0077.v1
Subject: Biology And Life Sciences, Anatomy And Physiology Keywords: glutamate; glutamine; BBB (blood brain-barrier); brain; oxoproline; amino acid transport
Online: 23 September 2016 (03:23:29 CEST)
A facilitative transport system exists on the blood brain barrier (BBB) that has been tacitly assumed to be a path for glutamate entry to brain. But glutamate is a non-essential amino acid whose brain content is much greater than plasma, and studies in vivo show that glutamate does not enter brain in material quantities except in those small regions with fenestrated capillaries (circumventricular organs). The situation became understandable when luminal (blood facing) and abluminal (brain facing) membranes were isolated and studied separately. Facilitative transport of glutamate and glutamine exist only on the luminal membranes whereas Na+-dependent transport systems for glutamate, glutamine and some other amino acids are present only on the abluminal membrane. The Na+-dependent cotransporters of the abluminal membrane are in a position to actively transport amino acids from the extracellular fluid (ECF) into the endothelial cells of the BBB. These powerful secondary active transporters couple the energy of the Na+-gradient to move glutamate and glutamine into the ECF whereupon glutamate can exit to blood on the luminal facilitative glutamate transporter. Glutamine may also exit brain on a separate facilitative transport system that exists on the luminal membranes or glutamine can be hydrolyzed to glutamate within the BBB thereby releasing ammonia that is freely diffusible. The γ-glutamyl participate cycle participates indirectly by producing oxoproline (pyroglutamate) that stimulates almost all secondary active transporters yet discovered in the abluminal membranes of the BBB.
ARTICLE | doi:10.20944/preprints201608.0239.v1
Subject: Chemistry And Materials Science, Organic Chemistry Keywords: organotin compounds; dibutyltin compounds; tin α-amino acids compounds; thermal decomposition
Online: 31 August 2016 (10:43:02 CEST)
This paper describes the preparation and description of four new complexes [Bu2Sn(AA)Cl] (AA = glycine, DL-valine and L-leucine) and [Bu2SnPhen2] (Phen = DL-phenylalanine) They were characterized by elemental analyses of carbon, hydrogen, nitrogen, chlorine and tin; and by infrared, 119mSn-Mössbauer and 119mSn-RMN spectroscopies, and by the applications of TG and DSC techniques in dynamic helium atmosphere. For the [Bu2Sn(AA)Cl], trigonal bipyramidal tin species, AA were coordinated bidentatedly by the carboxylic oxygen and by the NH2 group. The [Bu2SnPhen2)], with tin atoms in trans-octahedral sites, had the Phen-coordinated by both carboxylic oxygen atoms.
ARTICLE | doi:10.20944/preprints202312.0281.v1
Subject: Biology And Life Sciences, Neuroscience And Neurology Keywords: metabolomics; amino acids; diagnostics; neonatal asphyxia; liquid chromatography–mass spectrometry; newborn screening
Online: 5 December 2023 (15:31:23 CET)
Hypoxic-ischemic encephalopathy (HIE) is one of the most common causes of childhood disability. Hypothermic therapy is currently the only approved neuroprotective approach. However, early diagnosis of HIE can be challenging, especially in the first hours after birth when the decision to treat with hypothermic therapy is critical. Differentiating HIE from other neonatal conditions, such as sepsis, further complicates the diagnosis. This study investigated the utility of a metabolomic-based approach using the NeoBase 2 MSMS kit to diagnose HIE using dry blood stains in a Rice-Vannucci model of HIE in rats. We evaluated the diagnostic accuracy of this method between 3 and 6 hours after the onset of HIE, including in the context of systemic inflammation and concomitant hypothermic therapy. Discriminant analysis revealed several metabolite patterns associated with HIE. A logistic regression model using glycine levels achieved high diagnostic accuracy with areas under the curve (AUC) of 0.94 at 3 hours and 0.96 at 6 hours after the onset of HIE. In addition, orthogonal partial least squares discriminant analysis, which included five metabolites, achieved 100% sensitivity and 80% specificity within 3 hours of HIE. These results highlight the significant potential of the NeoBase 2 MSMS kit for the early diagnosis of HIE and could improve patient management and outcomes in this serious illness.
REVIEW | doi:10.20944/preprints202309.0394.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: non-canonical amino acid; genetic code expansion; biosynthesis; incorporation; tailor-made protein
Online: 6 September 2023 (09:41:40 CEST)
The emergence of non-canonical amino acids (ncAAs) has enriched the functional pool inherent in canonical amino acids (cAAs). ncAAs are important building blocks in the production of various pharmaceuticals. The biosynthesis of ncAAs has emerged as an alternative to traditional chemical synthesis because of its environmental friendliness and high efficiency. The breakthrough genetic code expansion (GCE) technique developed in recent years has allowed for the incorporation of ncAAs into target proteins, giving them special functions and biological activities. Biosynthesis of ncAAs and their incorporation into target proteins within a single microbe has become an enticing application of such molecules. Based on that, in this study we first review the biosynthesis methods for ncAAs and analyze the difficulties in biosynthesis. We then summarize the GCE methods and analyze their advantages and disadvantages. Further, we review the application progress of ncAAs and anticipate the challenges and future development directions of ncAAs.
SHORT NOTE | doi:10.20944/preprints202308.1339.v1
Subject: Chemistry And Materials Science, Organic Chemistry Keywords: 1,2,3-triazole; 4-amino-1,2,4-triazole-3-thiol; condensation; heterocycles; crystal structure
Online: 18 August 2023 (08:10:46 CEST)
The reaction of 2-bromo-1-(5-methyl-1-(4-nitrophenyl)-1H-1,2,3-triazol-4-yl)ethan-1-one (1) with 4-amino-5-((2,4-dichlorophenoxy)methyl)-4H-1,2,4-triazole-3-thiol (2) in absolute ethanol in the presence of triethyl amine as catalyst gave 2-((4-amino-5-((2,4-dichlorophenoxy)methyl)-4H-1,2,4-triazol-3-yl)thio)-1-(5-methyl-1-(4-nitrophenyl)-1H-1,2,3-triazol-4-yl)ethan-1-one (3) in 73% yield. The structure of the title heterocycle (3) was confirmed by X-ray single crystal diffraction and spectral analyses (NMR and IR).
REVIEW | doi:10.20944/preprints202306.1724.v1
Subject: Biology And Life Sciences, Endocrinology And Metabolism Keywords: canine mammary tumors; metabolism, cancer; mitochondria; metabolic reprogramming; glucose; amino acids; lipids
Online: 25 June 2023 (08:00:35 CEST)
Canine mammary tumors (CMTs) are among the most common disease in female dogs and share similarities with human breast cancer, which have placed these animals as a model of study in comparative oncology. Metabolic reprogramming is one of them and is known as a hallmark of carcinogenesis whereby cells undergo adjustments to supply the high bioenergetic and biosynthetic demands of rapidly proliferating cells. However, such alterations are also vulnerabilities that may serve as therapeutic strategies which have been tested mostly in human clinical trials, but poorly explored in CMTs. In this dedicated review, we compilated the metabolic changes described for CMTs emphasizing the metabolism of carbohydrates, amino acids, lipids, and mitochondrial function. We observed here key factors associated with the presence and aggressiveness of CMTs, such as the increase in glucose uptake followed by enhanced anaerobic glycolysis via upregulation of glycolytic enzymes, changes in glutamine catabolism due to overexpression of glutaminases, raise in fatty acid oxidation and distinct effects depending on the lipid saturation, in addition to mitochondrial DNA which is a hotspot for mutations. Therefore, more attention should be paid to this topic given that targeting metabolic fragilities could improve the outcome of CMTs.
ARTICLE | doi:10.20944/preprints202304.1133.v1
Subject: Biology And Life Sciences, Endocrinology And Metabolism Keywords: Non-alcoholic fatty liver disease; magnetic resonance imaging; amino acids; metabolomics; inflammation
Online: 28 April 2023 (07:20:14 CEST)
Background & Aims: Non-alcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH) have been linked to changes in amino acid (ΑΑ) levels. The current observational study sought to investigate the relationship between plasma AA concentrations in a NAFLD population and MRI parameters reflecting inflammation and fibrosis, inflammatory and oxidative stress markers, and disease-related anthropometric and biochemical indicators. Approach & Results: Plasma AA levels were quantified with liquid chromatography in 97 NAFLD patients from the MAST4HEALTH study. Medical, anthropometric and lifestyle characteristics were collected and biochemical parameters, as well as inflammatory and oxidative stress biomarkers were measured. In total, males and subjects with higher MRI-proton density fat fraction (MRI-PDFF) exhibited higher plasma AA levels compared to females and subjects with lower PDFF respectively. Several associations of AAs with disease related markers were revealed, with the more prominent ones being those of aromatic amino acids with log-PDFF (beta: 1.190E-02, p-Value: 0.001) and log-ALT (beta: 7.55E-03, p-Value: 0.001), of branched amino acids with log-insulin (beta: 1.97E-03, p-Value: 1.16E-04) and of ethanolamine (beta: 0.036, p-Value: 3.65E-04) and L-ornithine (beta: 5.4E-04, p-Value: 0.021) with log-total antioxidant status (TAS). Conclusions: Plasma AA levels varied according to sex, BMI, and several MRI clinical factors. Furthermore, significant relationships were demonstrated between AA and several disease indicators, such as MRI parameters, biochemical and oxidative stress indices, showing the potential utility of AAs as diagnostic dis-ease-related indicators activity.
ARTICLE | doi:10.20944/preprints202207.0191.v1
Subject: Medicine And Pharmacology, Pharmacology And Toxicology Keywords: malaria diagnosis; Pfhrp2; amino acid repeats; sequence variation; genetic polymorphism; Plasmodium falciparum
Online: 13 July 2022 (07:49:05 CEST)
Malaria rapid diagnosis test (RDT) is crucial for managing the disease, and the effectiveness of detection depends on parameters such as sensitivity and specificity of the RDT. Several factors can affect the performance of RDT. In this study, we focus on pfhrp2 sequence variation and its impact on RDTs targeted by antigens encoded by pfhrp2. Field samples collected during cross-sectional surveys in Tanzania were sequenced to investigate pfhrp2 sequence diversity and evaluate the impact on HRP2-based RDT performance. We observed significant mean differences in amino acid repeats between current and previous studies. Several new amino acid repeats were found to occur at different frequencies, including types AAY, AHHAHHAAN and AHHAA. Based on the abundance of types 2 and 7 amino acid repeats, the binary predictive model was able to predict RDT insensitivity by about 69 % in the study area. About 85% of the major epitopes targeted by Monoclonal antibodies (MAbs) in RDT were identified. Our study suggests that the extensive sequence variation in the pfhrp2 could contribute to reduced RDT sensitivity. The correlation between the different combinations of amino acid repeats and the performance of RDT in different malaria transmission settings should be investigated further.
ARTICLE | doi:10.20944/preprints202111.0072.v1
Subject: Chemistry And Materials Science, Medicinal Chemistry Keywords: antimalarial drugs; artemisinins; ACTs; resistance; amino-artemisinins, pharmacokinetics; metabolism; Cmax; drug efficacy
Online: 3 November 2021 (09:10:50 CET)
Because of the need to replace the current clinical artemisinins in artemisinin combination therapies, we are evaluating fitness of amino-artemisinins for this purpose. These include the thiomorpholine derivative artemiside obtained in one scalable synthetic step from dihydroartemisinin (DHA) and the derived sulfone artemisone. We have recently shown that artemiside undergoes facile metabolism via the sulfoxide artemisox into artemisone and thence into the unsaturated metabolite M1; DHA is not a metabolite. Artemisox and M1 are now found to be approximately equipotent with artemiside and artemisone in vitro against asexual P. falciparum (Pf) blood stage parasites (IC50 1.5 – 2.6 nM). Against Pf NF54 blood stage gametocytes, artemisox is potently active (IC50 18.9 nM early-stage, 2.7 nM late-stage). Comparative drug metabolism and pharmacokinetic (DMPK) properties were assessed via po and iv administration of artemiside, artemisox and artemisone in a murine model. Following oral administration, the composite Cmax value of artemiside plus its metabolites artemisox and artemisone formed in vivo is some 2.6-fold higher than that attained following administration of artemisone alone. Given that efficacy of short half-life rapidly-acting antimalarial drugs such as the artemisinins is associated with Cmax, it is apparent that artemiside will be more active than artemisone in vivo, due to additive effects of the metabolites. As is evident from earlier data, artemiside indeed possesses appreciably greater efficacy in vivo against murine malaria. Overall, the higher exposure levels of active drug following administration of artemiside coupled with its synthetic accessibility indicate it is much the preferred drug for incorporation into rational new artemisinin combination therapies.
ARTICLE | doi:10.20944/preprints202007.0132.v1
Subject: Biology And Life Sciences, Biology And Biotechnology Keywords: coronavirus; spike protein; database; sequence alignment; mutation; homology model; hydrophobic amino acids
Online: 7 July 2020 (16:49:04 CEST)
Analysis of SARS-CoV-2 spike protein sequences of over 19 countries from biological databases submitted around the globe was carried out with help of bioinformatics tools and structure prediction databases. Initial data analysis showed entry of virus into different geographic regions started in the month of January 2020. Meanwhile, alignment of spike protein sequences of SARS-CoV-2 isolates from China and other countries revealed a critical mutation of D614G. Surprisingly, mutation D614G was not seen in early samples submitted in the month of January but gradually it started appearing globally from the month of March 2020. However, the mutations of amino acids in the spike protein other than D614G exhibiting similar pI and altered polarity were found to be specific to geographical regions. Besides, prediction of homology model for interaction of spike protein showed predominant role of chain C of trimeric spike protein in adhering receptor binding domain (RBD) of human ACE2 receptor. Furthermore, the prediction of glycosylation points has revealed that there are about 20 N-glycosylation potential sites on spike protein. We believe that the information present here would not only help in thorough understanding of infectivity but also enhance the knowledge of the scientific community in developing prophylactics and/or therapeutics for SARS-CoV19-2 virus.
ARTICLE | doi:10.20944/preprints202005.0127.v1
Subject: Medicine And Pharmacology, Internal Medicine Keywords: nonalcoholic fatty liver disease; nonalcoholic steatohepatitis; liver fibrosis; amino acids; insulin resistance
Online: 7 May 2020 (13:29:39 CEST)
Altered amino acid levels have been found in nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH). However, it is not clear whether this alteration is due to altered hepatic metabolism or insulin resistance. The aim of this study was to clarify the association among amino acid levels, fatty liver, and liver fibrosis while eliminating the influence of insulin resistance. NAFLD and liver fibrosis were diagnosed using transient elastography and subjects were divided in three groups: normal, NAFLD, and liver fibrosis. To exclude the influence of insulin resistance, the subjects were matched using the homeostasis model assessment of insulin resistance (HOMA-IR). The amino acid serum levels were compared among the groups. Of 731 enrolled subjects, 251 and 33 were diagnosed with NAFLD and liver fibrosis. Although significant differences were observed among the groups in the serum levels of most amino acids, all but those of glutamate and glycine disappeared after matching for HOMA-IR. The multivariate logistic regression revealed that glutamate, glycine, and HOMA-IR were independent risk factors for liver fibrosis. The altered serum levels of most amino acids were associated with insulin resistance, while the increase in glutamate and the decrease in glycine levels were strongly associated not only with insulin resistance, but also with altered liver metabolism in patients with liver fibrosis.
ARTICLE | doi:10.20944/preprints201712.0185.v1
Subject: Medicine And Pharmacology, Pediatrics, Perinatology And Child Health Keywords: SLC25A13; amino acid ratio; citrullinemia; latent liver dysfunction; mitochondrial aspartate-glutamate carrier
Online: 26 December 2017 (10:18:45 CET)
Citrullinemia is the earliest identifiable biochemical abnormality in neonates with intrahepatic cholestasis due to a citrin deficiency (NICCD) and it has been included in newborn screening panels using tandem mass spectrometry. However, only one neonate was positive among 600,000 infants born in Sapporo city and Hokkaido, Japan between 2006 and 2017. We investigated 12 neonates with NICCD who were initially considered normal in newborn mass screening (NBS) by tandem mass spectrometry, but were later diagnosed with NICCD by DNA tests. Using their initial NBS data, we examined citrulline concentrations and ratios of citrulline to total amino acids. Although their citrulline values exceeded the mean of the normal neonates and 80 % of them surpassed +3SD, all were below the cutoff of 40 nmol/mL. The ratios of citrulline to total amino acids significantly elevated in patients with NICCD compared to the control. By evaluating two indicators simultaneously, we could select about 80% of patients with missed NICCD. Introducing an estimated index comprising citrulline values and citrulline to total amino acid ratios could assure NICCD detection by NBS.
ARTICLE | doi:10.20944/preprints201710.0110.v1
Subject: Chemistry And Materials Science, Organic Chemistry Keywords: X-ray; arylhydrazones; 2-amino-1,1,3-propenetricarbonitrile; pyridazines; rate enhance under pressure
Online: 17 October 2017 (04:13:47 CEST)
The considerable biological and medicinal activities of pyridazines has stimulated considerable research on efficient syntheses of these derivatives. In the last decade, microwave irradiation has generally been used for the energy source. As demonstrated in recent studies, pressure reactor “Q-tubes” may be used to accelerate several of these reactions in a more optimal and safer manner (compared to microwaves). In these studies there has been postulated a pathway for the formation of pyridazino[5,4,3-de][1,6]naphthyridine derivatives . In this paper we consider this pathway, and an alternate pathway, for several reactions. Contrary to the suggestion in these studies the pathway in which initial dimerization of malononitrile was postulated could be excluded based on chemical evidence. The reactions performed were the reaction of arylhydrazonals 1a,b with benzylidinemalononitrile which afforded in Q-tube the 3-acyl-4-aryl-1-phenyl-6-amino-1,4-dihydropyridazines, and the reaction of arylhydrazonals 1a,b, malononitrile 9 and aromatic aldehydes 10a-g in Q-tubes which afforded the tricyclic systems 12a-n whose structure could be established by X-ray crystal structure determination. In conclusion, we have added to the work of the recent studies by excluding a reaction pathway for one of their reaction products.
ARTICLE | doi:10.20944/preprints202311.0954.v1
Subject: Chemistry And Materials Science, Polymers And Plastics Keywords: cyanate ester resin; amino-POSS; polycyanurate; glass transition temperature; thermal stability; gas permeability
Online: 15 November 2023 (10:02:49 CET)
Nanocomposites of cyanate ester resin (CER) filled with three different reactive amino-functionalized polyhedral oligomeric silsesquioxane (POSS) were synthesized and characterized. The addition of a small quantity (0.1 wt.%) of amino-POSS chemically grafted to the CER network led to increasing thermal stability of CER matrix. A significant increase of the glass transition temperature, Tg (DSC data), and the temperature of α relaxation, Tα (DMTA data), by 45-55 оС of CER matrix with loading of nanofillers was evidenced. CER/POSS films exhibited a higher storage modulus than that of neat CER in the temperature range investigated. It was evidenced that CER/aminopropylisobutyl (APIB)-POSS, CER/N-phenylaminopropyl (NPAP)-POSS, and CER/aminoethyl aminopropylisobutyl (AEAPIB)-POSS nanocomposites induced a more homogenous α relaxation phenomenon with higher Tα values and an enhanced nanocomposite elastic behavior. Furthermore, CER/amino-POSS nanocomposites possessed higher specific surface area, gas permeability (CO2, He), and diffusion coefficients (CO2) values than those for neat CER, due to increasing free volume of the nanocomposites studied that is very important for their gas transport properties. Permeability grew respectively by about 2 (He) and 3.5-4 times (СО2), and diffusion coefficient of CO2 increased approximately twice for CER/amino-POSS nanocomposites in comparison with the neat CER network. The efficiency of amino-functionalized POSS in improving the thermal and transport properties of the CER/amino-POSS nanocomposites increased in a raw of reactive POSS containing one primary (APIB-POSS) < eight secondary (NPAP-POSS) < one secondary and one primary (AEAPIB-POSS) amino groups. APIB-POSS had the least strongly pronounced effect, since it could form covalent bonds with the CER network only by reaction of one –NH2 group, while AEAPIB-POSS displayed the most highly marked effect, since it could easily be incorporated into the CER network via reaction of –NH2 and –NH– groups with –O–C≡N groups from CER.
REVIEW | doi:10.20944/preprints202308.2063.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: metastasis; flaxseed proteins; cancer treatment; radiotherapy; mechanobiology; proteoform level analysis; flaxseed amino-acids
Online: 31 August 2023 (03:54:42 CEST)
Flaxseed has been recognized as a valuable source of nutrients and bioactive compounds, including proteins that possess various health benefits. In recent years, studies have shown that flaxseed proteins, including albumins, globulins, glutelin, and prolamins, possess anti-cancer properties. These properties are attributed to their ability to inhibit cancer cell proliferation, induce apoptosis, and interfere with cancer cell signaling pathways, ultimately leading to the inhibition of metastasis. Moreover, flaxseed proteins have been reported to modulate cancer cell mechanobiology, leading to changes in cell behavior and reduced cancer cell migration and invasion. This review provides an overview of the anti-cancer properties of flaxseed proteins, with a focus on their potential use in cancer treatment. Additionally, it highlights the need for further research to fully establish the potential of flaxseed proteins in cancer therapy.
ARTICLE | doi:10.20944/preprints202305.0227.v1
Subject: Chemistry And Materials Science, Electronic, Optical And Magnetic Materials Keywords: carbene-metal-amide; thermally activated delayed fluorescence; cyclic (alkyl)(amino) carbene; photoluminescence; computational
Online: 4 May 2023 (08:13:09 CEST)
Gold-centered carbene-metal-amides (CMAs) containing cyclic (alkyl)(amino)carbenes (CAACs) are promising emitters for thermally activated delayed fluorescence (TADF). Aiming at design and optimization of new TADF emitters, we report a density functional theory study of over 60 CMAs with various CAAC ligands, systematically evaluating computed parameters in relation to photoluminescence properties. We demonstrate that the efficiency of TADF of CMAs, arising from a compromise of exchange energy and oscillator strength, is governed by the overlap of HOMO and LUMO orbitals, where HOMO is localized on amide and LUMO on Au-carbene. The S0 ground states and excited T1 states of the CMAs adopt approximately coplanar geometries of carbenes and amides, but rotate perpendicular in the excited S1 states, resulting in degeneracy or near-degeneracy of S1 and T1, accompanied with lowering of the S1-S0 oscillator strength from its maximum at coplanar geometries to near zero at rotated geometries. Based on computations, promising new TADF emitters are proposed and synthesized. Bright CMA complex (Et2CAAC)Au(carbazolide) is obtained and fully characterized to demonstrate that high radiative rates up to 106 s-1 can be obtained for the gold-CMA complexes with small CAAC-carbene ligands.
ARTICLE | doi:10.20944/preprints202211.0569.v1
Subject: Biology And Life Sciences, Biology And Biotechnology Keywords: amino acid analysis; AAA; protein hydrolysis; metrology; traceability; reference materials; internal standards; calibration
Online: 30 November 2022 (09:17:12 CET)
qNMR is a valuable technique for metrological studies due to the uniformity of its signal response for all chemical species of an isotope of interest, which enables compound-independent calibration. However, protein quantification remained challenging as large molecules produce wide, low-intensity signals that reduce the already low sensitivity. Combining qNMR with the hydrolysis of protein samples into amino acids circumvents many of these issues and facilitates the use of NMR spectroscopy for absolute protein and peptide quantification.In this work, different conditions have been tested for quantifying aromatic amino acids and proteins. First, we examined the pH-based signal shifts in the aromatic region. The preferable pH depends on the selection of the amino acids for quantification and which internal standard substance should be used to avoid peak overlap. Several aromatic compounds, such as terephthalic acid, sulfoisophthalic acid, and benzene tricarboxylic acid, have been applied as internal standards. The quantification of amino acids from an amino acid standard, as well as from a certified reference material (bovine serum albumin), was performed. Using the first two suggested internal standards, recovery was ~ 97 % for histidine, phenylalanine, and tyrosine at a concentration of approximately 1 mM in solution. Acidic hydrolysis of a certified reference material (CRM) of bovine serum albumin (BSA) and subsequent quantification of Phe and Tyr yielded recoveries of 98 ± 2 and 88 ± 4 %, respectively, at a protein concentration of 16 g/L or 250 µM.
ARTICLE | doi:10.20944/preprints202111.0304.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: amino acid permease; L-aspartic acid; Bacillus licheniformis; whole-cell biocatalyst; fermentation engineering
Online: 17 November 2021 (11:58:31 CET)
Amino acid efflux and influx transport systems play vital roles in industrial microorganisms’ cell growth and metabolism. However, although biochemically characterized, most amino acid transporters remain unknown at the molecular level in Bacillus licheniformis. This study focuses on the molecular and functional characterizations of three transporters, YdgF, YvbW, and YveA, mainly when catalyzing the cross-membrane flux of L-Aspartate. When growing in the minimal medium with L-Asp as the only carbon and nitrogen source, the growth of strains lacking proteins YdgF, YvbW, and YveA was significantly inhibited compared with wild-type strains, while supplementing the expression of the corresponding proteins in the single-gene knockout strains can alleviate the inhibition to some extent. Upon overexpression, the recombinant proteins mediate the accumulation of L-aspartate to varying degrees. Compared with wild-type strains, the single knockout strains of the three protein genes exhibited reduced absorption of L-aspartate. In addition, this paper focuses on the effects of these three proteins on the absorption of β-alanine, L-glutamate, D-serine, D-alanine, and glycine.
REVIEW | doi:10.20944/preprints202101.0120.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: mTOR; ATP; protein synthesis; autophagy; amino acids; nutrition; adipose tissue; muscle; sarcopenia; mitochondria
Online: 6 January 2021 (14:32:22 CET)
Background. Sarcopenia, defined as the loss of skeletal muscle mass and function, is a major clinical problem in many chronic illnesses, in cancer and in the elderly. Exercise and adequate nutrition, peculiarly dependents on availability of essential amino acids, considered the primary strategies for prevention and treatment of protein synthetic deficits, affect both the efficient scavenging of aged and overused protein molecules and the renewal, by maintaining muscular protein synthesis. Many questions still remain about the regulation of protein syntheses and degradation. Degradation of inefficient proteins or organelles is performed by the sum of micro and macro-autophagy plus ubiquitin-proteasome system, activities known as proteostasis, necessary to preserve and promote protein masses and consequently, the body’s reserves. However, how protein synthesis is regulated, and how activation of the mTOR complex may modulate and transduce the flow of information provided by exercise and nutrition to balance proteostasis and syntheses, is far from being fully understood. We suggest that energy production and availability, thus also mitochondria, may have a pivotal role in synchronizing activity and functional outcomes of protein syntheses, and that those syntheses, since higly energy demanding, are main effectors of AMPK dependent autophagy activation by consuming ATP and producing AMP. Conclusion. While in normal conditions protein syntheses drive autophagy activation by decreasing ATP to AMP ratio, conversely autophagy may be inefficiently activated when chronic both low production and consumption of ATP would result in lowest concentrations of AMP, and therefore both blunted rates of protein syntheses and autophagy would be observed. We suggest that this functional hypothesis may explain sarcopenia in many pathological conditions , as in cancer or in aging muscles.
ARTICLE | doi:10.20944/preprints202007.0377.v1
Subject: Biology And Life Sciences, Insect Science Keywords: mosquito; Anopheles; microbiota; malaria; Plasmodium; metabolism; immunity; TCA cycle; nitrogen excretion; amino acids
Online: 17 July 2020 (11:00:53 CEST)
The mosquito microbiota reduces the vector competence of Anopheles to Plasmodium and affects host fitness, it is therefore considered as a potential target to reduce malaria transmission. While immune induction, secretion of antimicrobials and metabolic competition are three typical mechanisms of microbiota-mediated protection against invasive pathogens in mammals, the involvement of metabolic competition or mutualism in mosquito-microbiota and microbiota-Plasmodium interactions has not been investigated. Here, we describe a metabolome analysis of the midgut of An. coluzzii provided with a sugar-meal or a blood-meal, under conventional or antibiotic-treated conditions. We observed that the antibiotic treatment affects the tricarboxylic acid cycle and nitrogen metabolism, notably resulting in decreased abundance of free amino acids. Linking our results with published data, we identified candidate pathways which may participate in microbiota/Plasmodium interactions via metabolic interactions or immune modulation.
ARTICLE | doi:10.20944/preprints202203.0332.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: protein determination; soft protein corona; hard protein corona; covalent immobilization; supernatant method; gold nanoparticles; latex polymer particles; gold sodium chloride method; amino acid analysis; aromatic amino acid analysis; AAAA; acid hydrolysis
Online: 24 March 2022 (14:32:48 CET)
Protein immobilization for the functionalization of particles is used in various applications, including biosensors, lateral-flow immunoassays (LFIA), bead-based assays, and others. Common methods for the quantification of bound protein are measuring protein in the supernatant before and after coating and calculating the difference. This popular approach has the potential for a significant overestimation of the amount of immobilized protein since layers not directly bound to the surface (soft protein corona) are usually lost during washing and handling. Only the layer directly bound to the surface (hard corona) can be used in subsequent assays. A simplified amino acid analysis method based on acidic hydrolysis and RP-HPLC-FLD of tyrosine and phenylalanine (aromatic amino acid analysis, AAAA) is proposed to directly quantify protein bound to the surface of gold nano- and latex microparticles. The results are compared with indirect methods such as colorimetric protein assays, such as Bradford, bicinchoninic acid (BCA), as well as AAAA of the supernatant. For both particle types, these indirect quantification techniques show a protein overestimation of up to 1700% compared to the direct AAAA measurements. In addition, protein coating on latex particles was performed both passively through adsorption and covalently through EDC/sulfo-NHS chemistry. Our results showed no difference between the immobilization methodologies. This finding suggests that usual protein determination methods are no unambiguous proof of a covalent conjugation on particles or beads.
ARTICLE | doi:10.20944/preprints202309.0720.v1
Subject: Biology And Life Sciences, Life Sciences Keywords: Piriformospora indica; nitrogen starvation; nitrogen metabolism; nitrate transporter; ammonium transporter; amino acid transporter; endophyte
Online: 12 September 2023 (03:36:42 CEST)
The root-colonizing endophytic fungus Piriformospora indica promotes root and shoot growth of its host plants. We show that growth promotion of Arabidopsis leaves is abolished when the seedlings are grown on media with nitrogen (N) limitation. The fungus neither stimulated the total N content nor did it promote 15NO3- uptake from agar plates to the leaves of the host under N-sufficient or N-limiting conditions. However, when the roots were co-cultivated with 15N-labelled P. indica, more label can be detected in the leaves of N-starved host plants, but not of plants supplied with sufficient N. Amino acid and primary metabolite profiles, as well as expression analyses of N metabolite transporter genes suggest that the fungus alleviates the adaptation of its host to the N limitation condition. P. indica alters the expression of transporter genes which participate in relocation of NO3-, NH4+ and N metabolites from the roots to the leaves under N limitation. We propose that P. indica participates in the plant´s metabolomic adaptation to N limitation by delivering reduced N metabolites to the host, alleviating metabolic N starvation responses, and reprogramming the expression of N-metabolism related genes.
ARTICLE | doi:10.20944/preprints202306.1230.v1
Subject: Biology And Life Sciences, Biology And Biotechnology Keywords: genetic code; symmetries; Fibonacci-like sequences; amino acids; ribonucleotides; patterns; hydrogen; atom; molecular mass
Online: 16 June 2023 (11:02:55 CEST)
In this work, we present a new way to study the genetic code mathematical and chemical structure, based on the use of mathematical computations involving some few recently designed Fibonacci-like sequences, the “seeds” (“initial conditions”) of which are chosen according to the chemical and physical data of the three amino acids serine, arginine and leucine, playing a prominent role in a recent symmetry classification scheme of the genetic code. It appears that these mathematical sequences, of the same kind as the famous Fibonacci series, apart from their usual recurrence relations, are highly interwinned by many useful linear relationships. Using these sequences and also various sums or linear combinations of them, we derive several physical and chemical quantities of interest, as the number of total coding codons, 61, obeying various degeneracy patterns, the detailed number of hydrogen atoms, the detailed number of atoms (H/CNOS) and the integer molecular mass (or nucleon number), in the side chains of the 61 “amino acids”, also in various degeneracy patterns, in agreement with those described in the literature. Also, unexpectedly but interestingly, we find, as a by-product, an accurate description of the very chemical structure of the four ribonucleotides uridine monophosphate (UMP), cytidine monophosphate (CMP), adenosine monophosphate (AMP) and guanosine monophosphate (GMP), the building blocks of RNA whose groupings, in three units, constitutes the triplet codons. In summary, we find a full mathematical and chemical connection with the “ideal sextet’s classification scheme” mentioned above as well as with several others, notably, the Findley-Findley-McGlynn symmetrical classification. We organize the content of the text in such a way that, besides the presentation of several new research results, it has also an educational dimension. The paper could therefore be read and the computations easily worked out, also by non-experts with mathematical background.
ARTICLE | doi:10.20944/preprints202302.0445.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: non-canonical amino acids; genetic code expansion; crystal structure; tRNA; cell-free protein synthesis
Online: 27 February 2023 (06:27:04 CET)
Pairs of pyrrolysyl-tRNA synthetase (PylRS) and tRNAPyl from Methanosarcina mazei and Methanosarcina barkeri are widely used for site-specific incorporations of non-canonical amino acids into proteins (genetic code expansion). Previously, we achieved full productivity of cell-free protein synthesis for bulky non-canonical amino acids, including Ne-((((E)-cyclooct-2-en-1-yl)oxy)carbonyl)-L-lysine (TCO*Lys), by using Methanomethylophilus alvus PylRS with structure-based mutations in and around the amino acid binding pocket (first-layer and second-layer mutations, respectively). Recently, the PylRS•tRNAPyl pair from a methanogenic archaeon ISO4-G1 was used for genetic code expansion. In the present study, we determined the crystal structure of the methanogenic archaeon ISO4-G1 PylRS (ISO4-G1 PylRS) and compared it with those of structure-known PylRSs. Based on the ISO4-G1 PylRS structure, we attempted the site-specific incorporation of Ne-(p-ethynylbenzyloxycarbonyl)-L-lysine (pEtZLys) into proteins, but it was much less efficient than that of TCO*Lys with M. alvus PylRS mutants. Thus, the first-layer mutations (Y125A and M128L) of ISO4-G1 PylRS, with no additional second-layer mutations, increased the protein productivity with pEtZLys up to 578% of that with TCO*Lys, at high enzyme concentrations in the cell-free protein synthesis.
Subject: Chemistry And Materials Science, Food Chemistry Keywords: tree peony flowers; sugars and organic acids; amino acids; polyphenols; GC-MS; LC-MS
Online: 20 March 2019 (15:09:50 CET)
Tree peony flowers are traditional ornamental and medicinal materials in China. In this study, 23 tree peony flowers at a broad color spectrum were analyzed. Gas chromatography-mass spectrometer (GC-MS) revealed that tree peony flowers are rich in sugars and organic acids. Up to 18 amino acids were identified by liquid chromatography-mass spectrometer (LC-MS), including all essential amino acids, except for methionine. The majority of amino acids were significant positively correlated with each other and were significant negatively correlated with glucose, fructose and galactose. A total of 11 polyphenols were identified in these tree fresh peony flowers by LC-MS. There was a high consistency in grouping peony flowers by using sugars and organic acids and amino acids, which differed from that based on color components and polyphenols. Tree peony flowers are also rich in K, Ca, Mg and Fe. In together, peony flowers can be a good resource of health-promoting compounds.
ARTICLE | doi:10.20944/preprints202307.1873.v1
Subject: Biology And Life Sciences, Food Science And Technology Keywords: hemp waste; food fortification; Ciclope; Futura 75; hemp flour; dough mixing; amino acids; fatty acids
Online: 27 July 2023 (09:26:19 CEST)
The edible portion of Cannabis sativa L. are the seeds. The seeds are generally used for the production of hemp oil, appreciated for the high percentage of α-linolenic acid. The waste obtained after seeds oil extraction, reduced in fine powder, is the subject of this study. Since hemp seeds are considered to be a source of many valuable bioactive compounds, the addition of hemp seed flour to durum wheat for making fortified bread could have an effect on the health of consumers. The aim of this study was to use variable percentages of hemp seed flour for the production of bread, and to determine the fortification impact on chemicals, texture, organoleptic characteristics, crumb color, changes in crumb texture, total polyphenols, free radical scavenging activity and amino acids contents. The rheological and chemical qualities of bread samples, obtained by using a durum wheat cultivar Ciclope fortified with defatted hemp seeds flours, were evaluated. The solid residue left after the extraction of the oil from seeds (generally thrown away as waste or added to feed) was shredded and sieved at 0.530 mm (Hemp 1) or 0.236 mm (Hemp 2). Samples of fortified breads were obtained by substitution of variable percentages of durum wheat flour with the two hemp flours (5%, 7.5%, and 10%). Fortified bread’s total phenolic content was in a range of 0.73±0.017 and 1.73±0.029 mg GAE/g and an-ti-radical scavenging activity was included in the range from 1.17±0.099 and 3.18±0.071mmol TEAC/100g, according to the increasing fortification. Comparison between bread made with Ciclope semolina and hemp flour fortified breads, showed a large increase in amino acid content in fortified samples ones. In particular, bread fortified with 10% Hemp 2 flour highlights a greater content of glutamic acid, tyrosine, proline and essential amino acids such as leucine and isoleucine, compared to the other samples with same percentage of substitution. The amount of hemp seed flour influenced the color of the crumb by increasing the yellow index from 18.24 (100% Ciclope) to 21.33 (bread with Hemp 2 flour at 5%).
ARTICLE | doi:10.20944/preprints202212.0403.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: Molecular evolution; Substitution matrix; Amino acid exchangeability; Models of sequence evolution; Protein evolution; Archaea; Bacteria
Online: 21 December 2022 (13:06:09 CET)
The factors that determine the relative rates of amino acid substitution during protein evolution are complex and they are known to vary among taxa. We estimated relative exchangeabilities for pairs of amino acids from clades spread across the tree of life and assessed the historical signal in the distances among these clade-specific models. We trained these models separately on collections of arbitrarily selected protein alignments and on ribosomal protein alignments. In both cases we found a clear separation between the models trained using multiple sequence alignments from bacterial clades and the models trained on archaeal and eukaryotic data. We assessed the predictive power of our novel clade-specific models of sequence evolution by asking whether fit to the models could be used to identify the source of multiple sequence alignments. Model fit was generally able to classify protein alignments correctly at the level of domain (bacterial versus archaeal), but the accuracy of classification at finer scales was much lower. The only exceptions to this were the relatively high classification accuracy for two archaeal lineages: Halobacteriaceae and Thermoprotei. Genomic GC content had a modest impact on relative exchangeabilities despite having a large impact on amino acid frequencies. Relative exchangeabilities involving aromatic residues exhibited the largest differences among models. There were a small number of exchangeabilities that exhibited large differences in comparisons among major clades and between generalized models and ribosomal protein models. Taken as a whole, these results reveal that a small number of relative exchangeabilities are responsible for much of the structure of the “model space” for protein sequence evolution. If we look beyond the information that these clade-specific models reveal about protein evolution the models themselves are likely to be useful tools for phylogenomic inference across the tree of life.