NADPH is an indispensable cofactor in a wide range of physiological processes which is generated by a family of NADPH-dehydrogenases, where the NADP-dependent malic enzyme (NADP-ME) is one member of these enzymes. Pepper (Capsicum annuum L.) fruit is a horticultural product worldwide consumed which has great nutritional and economic relevance. Besides the phenotypical changes that undergo pepper fruit during ripening, there are many associated modifications at transcriptomic, proteome ic, biochemical, and metabolic levels. Nitric oxide (NO) is a recognized signal molecule that can exert regulatory functions in diverse plant processes. To our knowledge, there is very scarce information about the number of genes encoding for NADP-ME in pepper plants and their expression during the ripening of sweet pepper fruit. Based on a data-mining approach on the pepper plant genome and fruit transcriptome (RNA-seq), five NADP-ME genes were identified, and four of them, namely CaNADP-ME2 to CaNADP-ME5, were expressed in fruit. The time-course expression analysis of these genes during different fruit ripening stages including green immature (G), breaking point (BP), and red ripe (R) showed that they were differentially modulated. Thus, while CaNADP-ME3 and CaNADP-ME5 were upregulated, CaNADP-ME2 and CaNADP-ME4 were downregulated. Exogenous NO treatment of fruit triggered the downregulation of CaNADP-ME4. Furthermore, the analysis of the cis-regulatory elements showed that CaNADP-ME2 and CaNADP-ME5 were positively regulated by the light-responsive element Box4 whereas CaNADP-ME4 was by ABRE (ACGT-containing abscisic acid response element), which is involved in the abscisic acid (ABA) responsiveness. To get deeper knowledge on this enzyme system from fruits, we obtained the 50-75% ammonium-sulfate-enriched protein fraction containing CaNADP-ME enzyme activity, and this was assayed by non-denaturing polyacrylamide gel electrophoresis (PAGE). The results allowed identifying four isozymes designated CaNADP-ME I to CaNADP-ME IV. Taken together, the data provide new pieces of information on the CaNADP-ME system with the identification of five CaNADP-ME genes and how the four genes expressed in pepper fruits are modulated during ripening and by exogenous NO gas treatment.

Capsicum is the genus where a number of species and varieties have pungent features due to the exclusive content of capsaicinoids such as capsaicin and dihydrocapsaicin. In this work, the main enzymatic and non-enzymatic systems in pepper fruits from four varieties with different pungent capacity has been investigated at two ripening stages. Thus, a sweet pepper variety (Melchor) from California type fruits, and three autochthonous Spanish varieties were used, including Piquillo, Padrón and Alegría riojana. The capsaicinoids contents were determined in pericarp and placenta from fruits showing that these phenyl-propanoids were mainly localized in placenta. The activity profile of catalase, superoxide dismutase (SOD, total and isoenzymatic), the enzymes of the ascorbate-glutathione cycle (AGC) and four NADP-dehydrogenases indicate that some interaction with the capsaicinoid metabolism seems to occur. Among the results obtained on enzymatic antioxidant, the role of an Fe-SOD and the glutathione reductase from the AGC is highlighted. Additionally, it was found that ascorbate and glutathione content were higher in those pepper fruits which displayed the greater contents of capsacinoids. Taken together, all these data indicate that antioxidants may contribute to preserve capsaicinoids metabolism to maintain their functionality in a framework where NADPH is perhaps playing an essential role.

Glioblastoma, a deadly brain tumor, shows limited response to standard therapies like te-mozolomide (TMZ). Recent findings from the REGOMA trial underscore a significant survival improvement offered by regorafenib (REGO) in recurrent glioblastoma. Our study aimed to propose a 3D ex vivo drug response precision medicine approach to investigate recurrent glio-blastoma sensitivity to REGO and elucidate the underlying molecular mechanisms involved in tumor resistance or responsiveness to treatment. 3D glioblastoma organoids (GB-EXPs) obtained from 18 patients’ resected recurrent glioblastoma tumors were treated with TMZ and REGO. Drug responses were evaluated using NAD(P)H FLIM, stratifying tumors as responders (Resp) or non-responders (NR). Whole-exome sequencing was performed on 16 tissue samples, and whole-transcriptome analysis on 13 GB-EXPs treated and untreated. We found 35% (n=9) and 77% (n=20) of tumors responded to TMZ and REGO, respectively, with no instances of TMZ-Resp be-ing REGO-NR. Exome analysis revealed a unique mutational profile in REGO-Resp tumors compared to NR tumors. Transcriptome analysis identified distinct expression patterns in Resp and NR tumors, impacting Rho GTPase and NOTCH signaling, known to be involved in drug response. In conclusion, recurrent glioblastoma tumors were more responsive to REGO com-pared to TMZ treatment. Importantly, our approach enables a comprehensive longitudinal ex-ploration of the molecular changes induced by treatment, unveiling promising biomarkers in-dicative of drug response.

7α- and 7β-hydroxysteroid dehydrogenases (HSDH) are a pair of enzymes that can catalyze the isomerization of hydroxyl group at site 7 of bile acids. In previous study, we found that the activities of 7α- and 7β-HSDH can be inhibited by bilirubin. In order to clarify the impact, the effects of bilirubin on enzymes were studied by kinetics, spectrum and docking analysis. Relative activity of 7α-HSDH remained less than 40 % under 1 mM bilirubin, for 7β-HSDH, only 18 % activity left at the same condition. Using taurochenodeoxycholic acid (TCDCA) as substrate, the Km of 7α-HSDH was up to 0.63 mM from 0.24 mM after binding with bilirubin, the Km of 7β-HSDH rose from 1.14 mM to 1.87 mM for the catalysis of tauroursodeoxycholic acid (TUDCA). The affinity of 7α- and 7β-HSDH to substrate decreased with the effect of bilirubin. The binding of bilirubin with 7α- or 7β-HSDH were analyzed by UV–Vis spectra, Fluorescence spectra and Circular dichroism (CD) spectra. The results reflected that bilirubin caused a slight change in the secondary structure of 7α- or 7β-HSDH, and the changes were correlated with the ratio of bilirubin to enzyme. 10 candidate molecular docking results were presented to reflect the binding of bilirubin with 7α- or 7β-HSDH and to explore the inhibition mechanism. This research not only provides the more in-depth understanding of 7α- and 7β-HSDH, but also reminds us to avoid the inhibition of bilirubin on hydroxysteroid dehydrogenases.

Succinic semialdehyde dehydrogenase (SSADH) is a mitochondrial enzyme involved in the catabolism of the neurotransmitter γ-amino butyric acid. Pathogenic variants in the gene encoding this enzyme cause SSADH deficiency, a developmental disease manifesting as hypotonia, autism and epilepsy. SSADH deficiency patients usually have family-specific gene variants. Here, we describe a family exhibiting four different SSADH variants, Val90Ala, Cys93Phe, and His180Tyr/Asn255Asp (a double variant). We provide a structural and functional characterization of these variants and show that Cys93Phe and Asn255Asp are pathogenic variants that affect the stability of the SSADH protein. Due to impairment of the cofactor NAD+ binding, these variants show a highly reduced enzyme activity. However, Val90Ala and His180Tyr exhibit normal activity and expression. The His180Tyr/Asn255Asp variant exhibits a highly reduced activity as a recombinant species, is inactive and shows a very low expression in eukaryotic cells. A treatment with substances that support protein folding by either increasing chaperone protein expression or by chemical means was not capable of increasing the expression of the pathogenic variants of the SSADH deficiency patient. However, stabilization of the folding of pathogenic SSADH variants by other substances may provide a treatment option for this disease.

D-Glucaric acid is an important bio-based building block of polymers and is a high value-added chemical that can be used in a variety of applications. In the present study, the Udh target genes from Pseudomonas putida and Pseudomonas syringae were used together to construct the expression vector pETDuet-2×Udh. The transformants of BL21(DE3) with vector pETDuet-2×Udh was applied to produce glucaric acid from glucuronic acid. After optimization of induction conditions, the highest Udh expression were achieved when 0.4 mmol L-1 isopropyl-β-d–thiogalactoside (IPTG) was added to cell cultures at an OD600 value of 0.6 followed by culture at 26℃ for 6 hours. The production of glucaric acid substantially reached 5.24 ± 0.015 g L-1 in fed-batch cultures in a 30 L tank. In the present study, a new system for glucaric acid production was established, which was more economic and friendly to environment.

Baeyer-Villiger monoxygenases (BVMOs) are flavin-dependant oxidative enzymes capable to catalyse the insertion of an oxygen atom between a carbonylic Csp2 and the Csp3 at the alpha position, therefore transforming linear and cyclic ketones into esters and lactones. These enzymes are dependent on nicotinamides (NAD(P)H) for the flavin reduction and subsequent reaction with molecular oxygen to furnish peroxyflavin, the ultimate responsible for the substrate oxidation. BVMOs can be included in cascade reactions, coupled to other redox enzymes such as alcohol dehydrogenases (ADHs) or ene-reductases (EREDs), so that the direct conversion of alcohols or α,β-unsaturated carbonylic compounds to the corresponding esters can be achieved. This way, it is possible to develop smart synthetic strategies with a convenient cofactor recycling, both using whole cells (native or genetically engineered) as well as isolated enzymes, via multi-steps reaction through sequential or parallel methodologies. Some examples will be commented dealing with these biotransformations, highlighting the advantages of the coupling of enzymatic steps.

Direct electron transfer (DET)-type bioelectrocatalysis, which couples electrode reactions and catalytic functions of redox enzymes without any redox mediator, is one of the most intriguing subjects studied over the past decades in the field of bioelectrochemistry. In order to realize the DET-type bioelectrocatalysis and to improve the performance, nanostructures of the electrode surface have to be carefully tuned for each enzyme. In addition, enzymes can also be tuned by protein engineering approach for the DET-type reaction. This review summarizes the resent progresses in this field of the research, while taking into consideration of the importance of nanostructure of electrodes as well as redox enzymes. Described are basic concepts and theoretical aspects of DET-type bioelectrocatalysis, significance of nanostructures as scaffolds for DET-type reactions, protein engineering approached for DET-type reactions, and concepts and facts of bidirectional DET-type reactions, from a cross-disciplinary viewpoint.