ARTICLE | doi:10.20944/preprints201912.0265.v1
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.
REVIEW | doi:10.20944/preprints202012.0220.v1
Subject: Biology, Anatomy & Morphology 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.
Subject: Life Sciences, Biochemistry 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/preprints202104.0677.v1
Subject: Chemistry, 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 & Pharmacology, Oncology & 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/preprints202107.0210.v1
Subject: Life Sciences, Biochemistry 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/preprints202105.0293.v1
Subject: 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 & Pharmacology, Oncology & 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, Anatomy & Morphology 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.
REVIEW | doi:10.20944/preprints201801.0047.v1
Subject: Life Sciences, 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/preprints201812.0263.v1
Subject: Chemistry, 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.
ARTICLE | doi:10.20944/preprints201911.0216.v1
Subject: Life Sciences, Other 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/preprints201911.0189.v1
Subject: Medicine & Pharmacology, Nutrition 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.
COMMUNICATION | doi:10.20944/preprints202109.0457.v1
Subject: Life Sciences, 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/preprints202105.0021.v1
Subject: Life Sciences, Biochemistry 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/preprints201804.0073.v1
Subject: Chemistry, 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.
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.
REVIEW | doi:10.20944/preprints202007.0698.v1
Subject: Medicine & Pharmacology, Oncology & 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
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.
REVIEW | doi:10.20944/preprints202112.0331.v1
Subject: Life Sciences, Biochemistry 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: Materials Science, General Materials Science 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 & Pharmacology, 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.
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, 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: 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: Life Sciences, Biochemistry 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: Materials Science, Surfaces, Coatings & 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/preprints202209.0133.v1
Subject: Medicine & Pharmacology, Oncology & 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: Life Sciences, Biochemistry 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: Mathematics & Computer Science, 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, 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: Life Sciences, Immunology 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/preprints202012.0696.v1
Subject: Medicine & Pharmacology, Allergology 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: 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: Life Sciences, Biochemistry 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 & Pharmacology, Oncology & 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 & Pharmacology, 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, 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, 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/preprints202207.0191.v1
Subject: Medicine & Pharmacology, Other 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, 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: Life Sciences, 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 & Pharmacology, General Medical Research 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 & Pharmacology, Pediatrics 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, 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/preprints202111.0304.v1
Subject: Biology, Other 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: Life Sciences, Biochemistry 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, Entomology 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: Life Sciences, Biochemistry 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.
Subject: Chemistry, 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/preprints202204.0137.v1
Subject: Biology, Animal Sciences & Zoology Keywords: Taihe silky fowl; metabolic components; un-targeted metabolome; breed and feed; biosynthesis of amino acids
Online: 15 April 2022 (05:47:06 CEST)
Chinese Taihe Black-bone silky fowl (TBsf) is the homology of medicine and food and has high nutritional and medical value all over the world. However, the nutritional compositions and specific metabolite advantages of Taihe silky fowl muscle are still poorly understood. In this study, we investigated the differences of nutritional components between TBsf and another similar breed (Black Feathered chicken and laid green-shelled eggs, BF-gsc). Meanwhile, we also explored the divergences in muscle characteristics of Taihe silky fowl fed with two different diets, that is normal chicken feed (TBsf-ncf) and Broussonetia papyrifera-fermented feed (TBsf-bpf). Firstly, the growth performance and biochemical index of Taihe silky fowl was significantly different compared with black-feathered chicken. Secondly, we identified the metabolic alterations in Taihe silky fowl by performing an un-targeted UHPLC-Q-TOF-MS/MS analysis. Our results suggested that the whole metabonomic characteristics had obvious separation between TBsf-ncf, TBsf-bpf and BF-gsc groups both in the positive and negative ion mode by PCA analysis. Next, OPLS-DA multivariate analysis revealed that 57 metabolites (in positive mode) and 49 metabolites (in negative mode) were identified as differential metabolites between TBsf-ncf and BF-gsc group. These differential metabolites were mainly enriched to ABC transporters, biosynthesis of amino acids and aminoacyl-tRNA biosynthesis. Besides, there were 47 metabolites (in positive) and 13 metabolites (in negative) were differentially regulated between TBsf-ncf and TBsf-bpf group, which were majorly involved in histidine metabolism and linoleic metabolism. Furthermore, the integrated network analysis suggested that DL-arginine, DL-isoleucine, linoleoylcarnitine, stearoylcarnitine (positive) and ricionleic acid, D-proline, uric acid (negative) were the significantly metabolic biomarkers in Taihe silky fowl. Moreover, the metabolites of primaquine, ticlpoidine, riboflavin, acetylcarnitine (positive) and salicylic acid, acetaminophen sulfate, glutamic acid (negative) were markedly changed in the Taihe silky fowl fed with BP-fermented feed. In summary, a global survey of the nutritional components and metabolite differences were performed in muscle tissues of Taihe silky fowl between various breeds and feeds. The comprehensive expression profiles of the metabolites in Taihe silky fowl affected by genetic and environmental factors were acquired. This study provided valuable evidence fo breed and feed-induced putative biomarkers as well as improved the economic value of Taihe silky fowl through targeted metabolite regulation.
REVIEW | doi:10.20944/preprints202103.0500.v1
Subject: Chemistry, Analytical Chemistry Keywords: cyclolinopeptide A; cyclosporine A; immunosuppression; PGE2; edge-to-face; cis-peptide bond; homo amino acids
Online: 19 March 2021 (12:53:06 CET)
The consequences of manipulations in structure and amino acid composition of native cyclolinopeptide A (CLA) from linen seeds and its linear precursor on their biological activities and mechanisms of action are reviewed. The modifications included truncation of the peptide chain, replacement of amino acid residues with proteinogenic or non-proteinogenic ones, modifications of peptide bond, and others. The studies revealed changes in the immunosuppressive potency of these analogs investigated in a number of in vitro and in vivo experimental models, predominantly in rodents, as well as differences in their postulated mechanism of action. The modified peptides were compared with cyclosporine A and parent CLA. Some of the synthesized and investigated peptides show potential therapeutic usefulness.
REVIEW | doi:10.20944/preprints202103.0341.v1
Subject: Life Sciences, Biochemistry Keywords: prebiotic chemistry; origin of biomolecules; origin of nucleotides; origin of amino acids; origin of life
Online: 12 March 2021 (11:39:50 CET)
The origin of life was a cosmic event happened on primitive Earth. A critical problem to better understand the origins of life in Earth is to glimpse in which chemical scenarios the basic building blocks of biological molecules could be produced. Classic works in pre-biotic chemistry frequently considered early Earth as a homogeneous atmosphere constituted by chemical elements such as methane (CH4), ammonia (NH3), water (H2O), hydrogen (H2) and hydrogen sulfide (H2S). Under that scenario, Stanley Miller was capable to produce amino acids and solved the question about the origin of proteins. Conversely, the origin of nucleic acids has tricked scientists for decades as nucleotides are complex though necessary molecules to allow the existence of life. Here we review possible chemical scenarios that allowed not only the formation of nucleotides but also other significant biomolecules. We aim to provide a theoretical solution for the origin of biomolecules at specific sites named “Prebiotic Chemical Refugia”. A prebiotic chemical refugium should therefore be understood as a geographic site in prebiotic Earth on which certain chemical elements were accumulated in higher proportion than expected, facilitating the production of basic biomolecules. Plus, this higher proportion should not be understood as static, but dynamic; once the physicochemical conditions of our planet changed periodically. This different concentration of elements, together with geochemical and astronomical changes along days, synodic months and years provided somewhat periodic changes in temperature, pressure, electromagnetic fields, and conditions of humidity; among other features. Recent and classic works suggesting most likely prebiotic refugia on which the main building blocks of biological molecules might be accumulated are reviewed and discussed.
ARTICLE | doi:10.20944/preprints202009.0607.v1
Subject: Chemistry, Analytical Chemistry Keywords: Milk Serum; whey proteins; RP-HPLC-UV; free amino acids; RP-HPLC-FLD; antimicrobial study
Online: 25 September 2020 (11:45:09 CEST)
The aim of this study was characterization of some dairy drinks based on Milk Serum regarding major whey proteins (WP) and free amino acids (FAAs) using reversed phase high performance liquid chromatographic (RP-HPLC) methods. The studied WP, -lactalbumin (-La), bovine serum albumin (BSA), -lactoglobulin A (-Lg A) and -lactoglobulin B (-Lg B) were separated on Aeris XB-C18 column at 214 nm detection. The RP-HPLC method was validated by selectivity, linearity (R2 ≥0.99), sensitivity (LOQ, 1.35–10.08 µg mL−1), accuracy (recovery 96.79-103.07%) and precision (% RSD ≤ 4.13%). The total studied WP in studied dairy drinks varied between 1.42 and 3.047 g·L-1. The chromatographic profile of FAAs (aspartic acid, glutamic acid, serine, histidine, arginine, glycine, threonine, alanine, tyrosine, cysteine, tryptophan, methionine, valine, phenylalanine, isoleucine, leucine and lysine) was determined in lyophilized concentrate of Milk Serum by RP-HPLC using pre-column derivatization reaction with orthophthalaldehyde (OPA). The total studied FAAs in studied samples varied between 1.103 and 1.119 mg·g-1. Moreover, the Milk Serum showed bacteriostatic activity against two bacterial strains Escherichia coli and Staphylococcus aureus. The obtained results confirm that dairy drinks based on the Milk Serum constitutes a valuable sources of bioactive components with benefits for human healthy nutrition.
Subject: Life Sciences, Microbiology Keywords: branched-chain amino acid; ion-pair reversed-phase liquid chromatography; mastitis; dairy cow; staphylococcus aureus
Online: 18 September 2019 (16:51:46 CEST)
The early diagnosis of mastitis represents an essential factor for a prompt detection of the animal for further actions. In fact, if not culled, infected cows must be segregated from the milking herd and milked last, or milked with separate milking units. Besides microbiological analysis, the somatic cell count (SCC) commonly used as predictor of intramammary infection, frequently lead to a misclassification of milk samples. To overcome these limitations, more specific biomarkers are continuously evaluated. Total amino acid content increases significantly in mastitic milk compared to normal one. Bovine mastitis can arise as a result of infection of the mammary gland by Staphylococcus aureus. Multiplication of this bacterium within the mammary gland is required for infection to persist. S. aureus requires branched-chain amino acids (BCAAs: isoleucine, leucine, valine) for protein synthesis, branched-chain fatty acids synthesis and environmental adaptation by responding to their availability via transcriptional regulators. The importance of BCAAs for S. aureus physiology necessitates that it either synthesize them or scavenge them from the environment. Increase of BCAAs in composite milk has been postulated to be linked to mammary infection by S. aureus. In the present work, we demonstrated, by a direct ion-pairing reversed-phase method based on the use of the evaporative light-scattering detector (IP-RP-HPLC-ELSD), applied to 65 composite cow milk samples, a correlation between the concentration of isoleucine and leucine and S. aureus load.
ARTICLE | doi:10.20944/preprints202006.0228.v1
Subject: Biology, Horticulture Keywords: crop genetics; Solanum tuberosum; abiotic stress; phenylpropanoids; essential amino acid; transcriptome; small RNA; comparative genomics; nutrition
Online: 18 June 2020 (09:15:21 CEST)
Potato is among one of the most important food crops, yet maintaining plant productivity in this drought-sensitive crop has become a challenge. Competition for scarce water resources and the continued effects of global warming exacerbate current constraints on crop production. While plants’ response to drought in above-ground tissues has been well documented, the regulatory cascades in developing tubers have been largely unexplored. Using the commercial Canadian cultivar ‘Vigor’, plants were subjected to a drought treatment under high-tunnels causing a 4 ℃ increase in canopy temperature when compared to the well-watered control. Tubers were sampled for RNAseq and metabolite analysis. Approximately 2600 genes and 3898 transcripts were differentially expressed by at least four-fold in drought-stressed potato tubers, with 75 % and 69 % being down-regulated respectively. A further 229 small RNAs were implicated in gene regulation during drought. The comparison of protein homologues between Solanum tuberosum L. and Arabidopsis thaliana L. indicates that downregulated genes are associated with phenylpropanoid, carotenoid, and patatin biosynthesis. This suggests that there may be nutritive implications to drought stress occurring during the potato tuber bulking phase in sensitive cultivars.
ARTICLE | doi:10.20944/preprints202002.0022.v1
Subject: Life Sciences, Virology Keywords: influenza B virus; mammalian adaptation; amino acid substitutions; pathogenicity; influenza model; animal model; virulence; antiviral drugs
Online: 3 February 2020 (06:24:05 CET)
Over the years influenza B virus (IBV) contribute annual disease and can lead to serious respiratory disease among humans. More attention should be paid to the mammalian adaptive processes of B viruses and development of vaccines against current influenza. Because of preclinical trials of anti-influenza drugs are conducted mainly on mice, we developed adequate animal model using antigenically-relevant IBV strain for testing anti-influenza drugs and protective efficacy of flu vaccines. We serially passaged Victoria lineage (clade 1A) IBV 17 times in BALB/c mice. The adaptive amino acid substitutions were found in HA (T214I) and NA (D432N). By the electron microscopic examination, we showed spherical and elliptical shapes of IBV. Light microscopy showed that mouse-adapted B virus caused influenza pneumonia on day 6 post inoculation. We evaluated the illness pathogenicity, viral load and histopathological features of mouse-adapted IBV and estimated anti-influenza drugs and vaccine efficiency in vitro and in vivo. Assessment of investigational anti-influenza drug oseltamivir ethoxisuccinate and flu vaccine Ultrix® revealed effectivity against our mouse-adapted influenza B virus.
ARTICLE | doi:10.20944/preprints201901.0232.v1
Subject: Life Sciences, Other Keywords: protein function, mtORF, Stylophora, thermal adaptation, disordered amino acids residues, pocilloporid corals, a transmembrane protein, pocilloporid corals.
Online: 23 January 2019 (08:58:41 CET)
More than a decade ago, a new mitochondrial Open Reading Frame (mtORF) was discovered in corals of the family Pocilloporidae, which turn out to be an effective barcode gene for these corals. However, its function remains unknown. Recently, this gene revealed the existence of a hybrid Stylophora lineage (RS_LinA) inhabiting in sympatry along the environmental gradient of the Red Sea (18.5°C to 33.9°C) with its parental species (RS_LinB). Furthermore, in RS_LinB, the mtORF uncovered phylogeographic patterns that were strongly correlated with environmental variations. This was similar to the patterns unraveled by hsp70, suggesting that mtORF too might be involved in thermal adaptation. Here we used computational approaches to characterize the mtORF and to identify its potential role. Results showed that this gene encodes a transmembrane protein (0.97<P< 1.00) involved in transport (0.80<P< 0.87), regulation of metabolic processes (0.70<P<0.85), and likely in the cell-surface receptor signaling pathway (0.56<P<0.80). Predicted protein functions differed among Stylophora lineages and interestingly, in RS_LinB only, the protein was intrinsically disordered and displayed domains involved in cellular complexes and stress response (0.0001< P <0.001). These characteristics, exclusive of an endemic lineage adapted to extreme environmental fluctuations, support a role of the mtORF in stress response, speciation and adaptation.
ARTICLE | doi:10.20944/preprints202104.0528.v1
Subject: Life Sciences, Biochemistry Keywords: Interactomics; host-parasite-microbiome relationships; extra-intestinal effects; D-amino ac-id/SCFA-induced modulation; Yeast ubiquinone salvation.
Online: 20 April 2021 (11:12:14 CEST)
Cryptosporidiosis is a major human health concern globally. Despite well-established methods, misdiagnosis remains common. Our understanding of the cryptosporidiosis biochemical mechanism remains limited, compounding the difficulty of clinical diagnosis. Here, we used a systems biology approach to investigate the underlying biochemical interactions in C57BL/6J mice infected with Cryptosporidium parvum. Faecal samples were collected daily following infection. Blood, liver tissues and luminal contents were collected 10 days post infection (dpi). High-resolution liquid chromatography and low-resolution gas chromatography coupled with mass spectrometry were used to analyse the proteomes and metabolomes of these samples. Faeces and luminal contents were additionally subjected to 16S rRNA gene sequencing. Univariate and multivariate statistical analysis of the acquired data illustrated altered host and microbial energy pathways during infection. Glycolysis/citrate cycle metabolites were depleted, while short-chain fatty acids and D-amino acids accumulated. An increased abundance of bacteria associated with a stressed gut environment was seen. Host proteins involved in energy pathways and Lactobacillus glyceraldehyde-3-phosphate dehydrogenase were upregulated during cryptosporidiosis. Liver oxalate also increased during infection. Microbiome-parasite relationships were observed to be more influential than the host-parasite association in mediating major biochemical changes in the mouse gut during cryptosporidiosis. Defining this parasite-microbiome interaction is the first step towards building a comprehensive cryptosporidiosis model towards biomarker discovery, and rapid and accurate diagnostics.
ARTICLE | doi:10.20944/preprints202104.0344.v1
Subject: Mathematics & Computer Science, Algebra & Number Theory Keywords: Lysine; Rice; Amino Acids; Saline Stress; Abiotic Stress; Gene Regulatory Network; Bayesian Network; Parameter Estimation; Inference; RNA Seq
Online: 13 April 2021 (10:52:26 CEST)
Lysine is the first limiting essential amino acid in rice because it is present in the lowest quantity compared to all the other amino acids. Amino acids are the building block of proteins and play an essential role in maintaining the human body’s healthy functioning. Rice is a staple food for large proportion of the global population, thus increasing the lysine content in rice will improve its nutritional value. In this paper, we studied the lysine biosynthesis pathway in rice (Oryza Sativa) to identify the regulators of the lysine reporter gene LYSA (LOC_Os02g24354). Genetically intervening at the regulators has the potential to increase the overall lysine content in rice. We modeled the lysine biosynthesis pathway in rice seedlings under normal and saline (NaCl) stress conditions using Bayesian networks. We estimated the model parameters using experimental data and identified the gene DAPF(LOC_Os12g37960) as a positive regulator of the lysine reporter gene LYSA under both normal and saline stress conditions. Based on this analysis, we conclude that the gene DAPF is a potent candidate for genetic intervention. Upregulating DAPF using methods such as CRISPR-Cas9 has the potential to upregulate the lysine reporter gene LYSA and increase the overall lysine content in rice.
ARTICLE | doi:10.20944/preprints201911.0301.v2
Subject: Life Sciences, Genetics Keywords: genetic code; DNA; alphabet; amino acids; hypercomplex numbers; doubly stochastic matrix; binary numbers; dyadic groups; tensor product; palindrome
Online: 17 March 2020 (03:02:27 CET)
The article shows materials to the question about algebraic features of the genetic code and about the dictatorial influence of the DNA and RNA molecules on the whole organism. Presented results testify in favor that the genetic code is an algebraic code related with a wide class of algebraic codes, which are a basis of noise-immune coding of information in communication technologies. Structural features of the genetic systems are associated with hypercomplex double (or hyperbolic) numbers and with bisymmetric doubly stochastic matrices. The received results confirm that represented matrix approaches are effective for modeling genetic phenomena and revealing the interconnections of structures of biological bodies at various levels of their organization. This allows one to think that living organisms are algebraically encoded entities where structures of genetic molecules have the dictatorial influence on inherited structures of the whole organism. New described algebraic approaches and results are discussed.
REVIEW | doi:10.20944/preprints202001.0315.v1
Subject: Medicine & Pharmacology, Pediatrics Keywords: succinic semialdehyde dehydrogenase deficiency; gamma-amino butyric acid; organic acidurias; enzyme replacement therapy; pharmacological chaperones; clinical trials; autophagy
Online: 26 January 2020 (08:10:19 CET)
Succinic semialdehyde dehydrogenase deficiency (SSADH-D) is a genetic disorder that results from the aberrant metabolism of the neurotransmitter γ-amino butyric acid (GABA). The disease is caused by the impaired activity of the mitochondrial enzyme succinic semialdehyde dehydrogenase. SSADH-D manifests as varying degree of mental retardation, autism, ataxia and epileptic seizures, but the clinical picture is highly heterogeneous. So far, there is no approved therapy for this disease. In this review, we briefly summarize the molecular genetics of SSADH-D, the past and ongoing clinical trials and the emerging features of the molecular pathogenesis, including redox imbalance and mitochondrial dysfunction. The main aim of this review is to discuss the potential use of further therapy approaches that have so far not been tested in SSADH-D, such as pharmacological chaperones, read-through drugs and gene therapy. Special attention will also be paid to elucidating the role of patient advocacy organizations in facilitating research and in the communication between the researchers and the patients.
ARTICLE | doi:10.20944/preprints201912.0374.v1
Subject: Life Sciences, Biophysics Keywords: alpha-fetoprotein; estrogens; selective estrogen receptor modulators; homology-based modeling; molecular docking; protein-ligand interaction; amino acid substitutions
Online: 29 December 2019 (08:08:23 CET)
Alpha-fetoprotein (AFP) is a major embryo- and tumor-associated protein capable of binding and transporting variety of hydrophobic ligands including estrogens. AFP has been shown to inhibit estrogen receptor (ER)-positive tumor growth and this can be attributed to its estrogen-binding ability. Despite AFP has long been investigated, its three-dimensional (3D) structure has not been experimentally resolved and molecular mechanisms underlying AFP-ligand interaction remain obscure. In our study we constructed homology-based 3D model of human AFP (HAFP) with the purpose to perform docking of ERα ligands, three agonists (17β-estradiol, estrone and diethylstilbestrol) and three antagonists (tamoxifen, afimoxifene and endoxifen) into the obtained structure. Based on ligand docked scoring function, we identified three putative estrogen- and antiestrogen-binding sites with different ligand binding affinities. Two high-affinity sites were located in (i) a tunnel formed within HAFP subdomains IB and IIA and (ii) opposite side of the molecule in a groove originating from cavity formed between domains I and III, while (iii) the third low-affinity site was found at the bottom of the cavity. 100 ns MD simulation allowed studying their geometries and showed that HAFP-estrogen interactions occur due to van der Waals forces, while both hydrophobic and electrostatic interactions were almost equally involved in HAFP-antiestrogen binding. MM/GBSA rescoring method estimated binding free energies (ΔGbind) and showed that antiestrogens have higher affinities to HAFP as compared to estrogens. We performed in silico point substitutions of amino acid residues to confirm their roles in HAFP-ligand interactions and showed that Thr132, Leu138, His170, Phe172, Ser217, Gln221, His266, His316, Lys453, and Asp478 residues along two disulfide bonds, Cys224-Cys270 and Cys269-Cys277 have key roles in both HAFP-estrogen and HAFP-antiestrogen binding. Data obtained in our study contribute to understanding mechanisms underlying protein-ligand interactions and anti-cancer therapy strategies based on ER-binding ligands.
ARTICLE | doi:10.20944/preprints202002.0234.v1
Subject: Life Sciences, Virology Keywords: adeno-associated virus; protein sequence analysis; overlapping genes; amino acid depletion; cysteine depletion; tyrosine depletion; capsid design; membrane-binding amphipathic helix
Online: 17 February 2020 (02:42:39 CET)
Adeno-associated viruses (AAVs, genus dependoparvovirus) are promising gene therapy vectors. In strains AAV1-12, the capsid gene VP1 encodes a recently discovered protein, MAAP, in an overlapping frame. MAAP binds the cell membrane by an unknown mechanism. We discovered that MAAP is also encoded in bovine AAV and in porcine AAVs (which have shown promise for gene transfer into muscle tissues), in which it is probably translated from a non-canonical start codon. MAAP is predicted to be mostly disordered except for a predicted C-terminal, membrane-binding amphipathic α-helix. MAAP has a highly unusual composition. In particular, it lacks internal methionines, and is devoid of tyrosines in most strains. Unexpectedly, we discovered that the N-terminus of VP1 also lacks several amino acids. In all AAVs that encode MAAP, the first 200 aas of VP1 are devoid of internal methionines, probably owing to a selection against ATG codons that could prevent translation of MAAP and of capsid isoforms (VP2, VP3). The N-terminus of VP1 also lacks cysteines, likely to avoid the formation of disulfide bridges when it becomes exposed outside of the capsid during post-endocytic trafficking. Finally, the region common to VP1 and VP2 lacks tyrosine in the vast majority of AAVs that encode MAAP. Avoiding these "forbidden" aas in MAAP and VP1 when creating recombinant AAV capsids might increase the efficiency of capsid design. Conversely, the presence of "forbidden" aas in some rare strains probably indicates that they have unusual properties that could help us understand the viral cycle.
ARTICLE | doi:10.20944/preprints201911.0339.v1
Subject: Chemistry, Medicinal Chemistry Keywords: human albumin; hydrogen bonds; hp contacts; π- π / cation-π interactions; bonds roughness; decay curve; power spectrum; interaction between amino-acids
Online: 27 November 2019 (09:35:09 CET)
In this paper we review dynamics and roughness of bonds in proteins on example of albumin, that is important from the physiological point of view. We have performed computer simulations of albumin chain. Statistics were collected by performing many simulations realizations for each experimental setting. We concentrate on hydrogen bonds, cation-π and π- π interactions and NP contacts. Histograms of hydrogen bonds length are positively skewed in contrary to histograms of interactions and HP contacts that are negatively skewed. Scaling exponents of power spectra of energies of bonds / interactions /contacts are in range -0.2 to -0.5 and significantly differ between various hydrogen bonds or interactions. Varying scaling of such spectra can be used to classify between distinct bonds or contacts. Concerning particular amino-acids, largest amount of HBO H20 bonds are between Glutamate (GLU) amino-acids and water particle, while large amount of HBO bonds are formed with Lysine (LYS). For HP contacts the mayor role plays Phenylalanine (PHE) and Leucine (LEU) amino-acids. From decay curves HBO H2O bonds decays in fastest rate, while HBO bonds and HP contacts at slowest rate. We present as well decay curves of bonds formed by particular amino-acids, that gives interesting results.
ARTICLE | doi:10.20944/preprints202103.0403.v1
Subject: Engineering, Biomedical & Chemical Engineering Keywords: non-canonical branched chain amino acids; scale-down; strain screening; mixed-acid fermentation; pyruvate pulse; norvaline; norleucine; fed-batch cultivation; bioreactor; Enpresso; Enbase
Online: 16 March 2021 (09:11:34 CET)
Insufficient mixing in large-scale bioreactors, provokes gradient zones of substrate, dissolved oxygen, pH and other parameters. E. coli responds to a high glucose, low oxygen feeding zone with the accumulation of mixed acid fermentation products, especially formate, but also with the synthesis of non-canonical amino acids, such as norvaline, norleucine and -methyl-norleucine. These amino acids can be mis-incorporated into recombinant products, which causes a problem for pharmaceutical production whose solution is not trivial. While these effects can also be observed in scale down bioreactor systems, these are challenging to operate. Especially the high-throughput screening of clone libraries is not easy, as fed-batch cultivations would need to be controlled via repeated glucose pulses with simultaneous oxygen limitation, as has been demonstrated in well controlled robotic systems. Here we show that not only glucose pulses in combination with oxygen limitation can provoke the synthesis of these non-canonical branched-chain amino acids, but also that pyruvate pulses produce the same effect. Therefore we combined the enzyme based glucose delivery method Enbase® in a PALL24 mini-bioreactor system and combined repeated pyruvate pulses with simultaneous reduction of the aeration rate. These cultivation conditions, produced an increase in the non-canonical branched chain amino acids norvaline and norleucine in both the intracellular soluble protein and inclusion body fractions with mini-proinsulin as an example product, and this effect was verified in a 15 L stirred tank bioreactor. To our opinion this cultivation strategy is easy to apply for the screening of strain libraries under standard laboratory conditions if no complex robotic and well controlled parallel cultivation devices are available.
ARTICLE | doi:10.20944/preprints201810.0599.v1
Subject: Chemistry, Organic Chemistry Keywords: (R)-1-(4-Amino-3,5-dichlorophenyl)-2-bromoethan-1-ol; (S)-N-(2,6-dichloro-4-(1-hydroxyethyl)phenyl)acetamide; clenbuterol; ketoreductase; chiral chromatography
Online: 25 October 2018 (08:44:19 CEST)
(R)-1-(4-Amino-3,5-dichlorophenyl)-2-bromoethan-1-ol has been synthesised in 93% enantiomeric excess (ee) by asymmetric reduction of the corresponding ketone catalysed by a ketoreductase and NADPH as the co-factor in DMSO. (S)-N-(2,6-Dichloro-4-(1-hydroxyethyl)phenyl)acetamide has been synthesised in >98% ee by the same system. Both synthons are potential precursors for clenbuterol enantiomers. Clenbuterol is a β2-agonist used in veterinary treatment of asthma in several countries. The drug is listed on the World Anti-doping Agency’s Prohibited list due to its effect on increased protein synthesis in the body. However, racemic clenbuterol has recently been shown to reduce the risk of Parkinson’s disease. In order to reveal which one (or both) of the enantiomers that cause this effect, the pure enantiomers need to be studied separately. Our biocatalytic approach in order to obtain enantiopure clenbuterol should be applicable to industrial scale.
REVIEW | doi:10.20944/preprints202106.0377.v2
Subject: Life Sciences, Biochemistry Keywords: aa = amino acids; ACE-2 = receptor angiotensin-converting enzyme 2; cDNA = complementary DNA; mRNA = messenger RNA; orf = open reading frame; RBD = receptor binding protein; S-protein = Spike protein; SARS-CoV-2 = severe respiratory syndrome coronavirus 2; Vaccines.
Online: 22 June 2021 (11:53:34 CEST)
The SARS (severe acute respiratory syndrome)-CoV (Coronavirus)-2 S(spike)-protein mRNA/cDNA currently being used as vaccines are antigenic but not antigens against SARS-CoV-2, that causes COVID (Coronavirus Disease) -19. Furthermore, the mRNA and cDNA antigenic vaccines also have potentials for homologous as well as heterologous recombination, primarily into the somatic cell DNA of the vaccine recipients. On the contrary, a SARS-CoV-2 RBD-protein antigen, a part of the S-protein, will directly stimulate antibody production against SARS-CoV-2. Hence, a vaccine composed of SARS-CoV-2 RBD-protein as a safer, fast acting, and effective vaccine against SARS-CoV-2 and thus against COVID-19. This is also useful for some immune compromised individuals.
ARTICLE | doi:10.20944/preprints201909.0146.v1
Subject: Life Sciences, Biophysics Keywords: entropy; entropy production; non-equilibrium thermodynamics; information encoding; nucleic acids; DNA; RNA; origin of life; origin of codons; amino acids; stereochemical era; photon potential
Online: 14 September 2019 (19:44:54 CEST)
Ultraviolet light incident on organic material can initiate its spontaneous dissipative structuring into chromophores which can catalyze their own replication. This may have been the case for one of the most ancient of all chromophores dissipating the Archean UVC photon flux, the nucleic acids. Oligos of nucleic acids with affinity to particular amino acids which foment UVC photon dissipation would have been selected through non-equilibrium thermodynamic imperatives which favor entropy production. Indeed, we show here that those amino acids with characteristics most relevant to fomenting UVC photon dissipation are precisely those with greatest chemical affinity to their codons or anticodons. Entropy production could thus provide an explanation for the accumulation of information in nucleic acids relevant to the dissipation of the externally imposed thermodynamic potentials. The accumulation of information in this manner provides a link between evolution and entropy production.
ARTICLE | doi:10.20944/preprints202109.0415.v2
Subject: Life Sciences, Virology Keywords: Delta variant; Variants of concern; Variants of interest; SARS-CoV-2; Spike protein; Nested RT-PCR; Sanger sequencing; Amino acid mutations; ACE2 RBD; N-terminal domain (NTD)
Online: 2 November 2021 (10:40:46 CET)
As SARS-CoV-2 continues to spread among human populations, genetic changes occur and accumulate in the circulating virus. Some of these genetic changes have caused amino acid mutations, including deletions, which may have potential impact on critical SARS-CoV-2 countermeasures, including vaccines, therapeutics, and diagnostics. Considerable efforts have been made to categorize the amino acid mutations of the angiotensin-converting enzyme 2 (ACE2) receptor binding domain (RBD) of the spike (S) protein along with certain mutations in other regions within the S protein as specific variants in an attempt to study the relationship between these mutations and the biological behavior of the virus. However, the currently used whole genome sequencing surveillance technologies can test only a small fraction of the positive specimens with high viral loads and often generate uncertainties in nucleic acid sequencing that needs additional verification for precision determination of mutations. This article introduces a generic protocol to routinely sequence a 437-bp nested RT-PCR cDNA amplicon of the ACE2 RBD and a 490-bp nested RT-PCR cDNA amplicon of the N-terminal domain (NTD) of the S gene for detection of the amino acid mutations needed for accurate determination of all variants of concern and variants of interest according to the definitions published by the U.S. Centers for Disease Control and Prevention. This protocol was able to amplify both nucleic acid targets into cDNA amplicons to be used as templates for Sanger sequencing on all 16 clinical specimens that were positive for SARS-CoV-2.
REVIEW | doi:10.20944/preprints202112.0469.v1
Subject: Medicine & Pharmacology, General Medical Research Keywords: astrocyte; gamma-amino butyric acid (GABA); GABA transporter (GAT); GABAA receptor; glutamic acid decarboxylase (GAD); glycine; glycine receptor; glycine transporter (GlyT); K+-Cl- co-transporter 2 (KCC2); vesicular GABA transporter (VGAT)
Online: 29 December 2021 (14:27:41 CET)
Gamma-aminobutyric acid (GABA) and glycine act as inhibitory neurotransmitters. Three types of inhibitory neurons and terminals, GABAergic, GABA/glycine co-releasing, and glycinergic, are orchestrated in the spinal cord neural circuits and play key roles in the regulation of pain, locomotive movement, and respiratory rhythms. Herein, we first describe GABAergic and glycinergic transmission and inhibitory networks, which consist of three types of terminals, in the mature mouse spinal cord. Second, we describe the developmental formation of GABAergic and glycinergic networks, with specific focus on the differentiation of neurons, formation of synapses, maturation of removal systems, and changes in their action. GABAergic and glycinergic neurons are derived from the same domains of the ventricular zone. Initially, GABAergic neurons are differentiated and their axons form synapses. Some of these neurons remain GABAergic in lamina I and II. Many of GABAergic neurons convert to co-releasing state. The co-releasing neurons and terminals remain in the dorsal horn, whereas many of co-releasing ones ultimately become glycinergic in the ventral horn. During the development of terminals and the transformation from radial glia to astrocytes, GABA and glycine receptor subunit compositions markedly change, removal systems mature, and GABAergic and glycinergic action shifts from excitatory to inhibitory.
ARTICLE | doi:10.20944/preprints202208.0004.v1
Subject: Life Sciences, Biochemistry Keywords: protein affinity enrichment; bioseparation; immunoprecipitation; immunocapture; affinity chro-matography; solid phase; carrier; material; corundum; polyglycerol; aromatic amino acid analysis; self-assembled monolayers (SAM), periodate oxidation; reductive amination; antibodies; IgG; im-munoglobulins; glutaraldehyde; polyglycerol; hyperbranched polymer
Online: 1 August 2022 (04:42:41 CEST)
Nonporous corundum powder, known as an abrasive material in the industry, was functionalized covalently with protein binders to isolate and enrich specific proteins from complex matrices. The materials based on corundum were characterized by TEM, ESEM, BET, DLS, and zeta potential measurements. The strong Al-O-P bonds between the corundum surface and amino phosphonic acids are used to introduce functional groups for further conjugations. The common crosslinker glutaraldehyde was compared with a hyperbranched polyglycerol (PG) of around 10 kDa. The latter is oxidized with periodate to generate aldehyde groups that can covalently react with the amines of the surface and the amino groups from the protein via a reductive amination process. The amount of bound protein was quantified via aromatic amino acid analysis (AAAA). This work shows that oxidized polyglycerol can be used as an alternative to glutaraldehyde. With polyglycerol, more of the model protein bovine serum albumin (BSA) could be attached to the surface under the same conditions, and lower nonspecific binding (NSB) was observed. As a proof of concept, IgG was extracted with protein A from crude human plasma. The purity of the product was examined by SDS-PAGE. A binding capacity of 1.8 mg IgG per g of corundum powder was achieved. The advantages of corundum are the very low price, extremely high physical and chemical stability, pressure resistance, favorable binding kinetics, and flexible application.