N-Acetyl-L-isoleucinol

Cardiac hypertrophy (CH), leading to cardiac failure is due to chronic metabolic alterations occurring during cellular stress. Besides the already known relationship between oxidative stress and CH, there are implications of reductive stress leading to CH. This study attempted to develop reductive stress-based CH rat model using n-acetyl-L-cysteine (NAC), a glutathione agonist that was compared with typical isoproterenol (ISO) induced CH model. The main objective was to identify serum metabolites that can serve as potent predictors for seven routine clinical and diagnostic parameters in CH: 3-hydroxybutyrate (3-HB), lactic acid (LA), urea, and ECG-CH parameters (QRS complex, R-amplitude, R-R interval, heart rate) that were hypothesized to underlie metabolic remodelling in this study. CH was assessed using electrocardiography, hypertrophic index and histopathological analysis (H&E stain) in both ventricles after 2 weeks. Gas chromatography mass spectroscopy analysis (GC-MS) identified unique metabolite finger-prints. Correlation and pattern analysis revealed strong relationships between specific metabolites and parameters (Pearson's score > 0.7) of this study. Multiple regression analysis (MRA) for the strongly related metabolites (independent variables) with each of the seven parameters (dependent variables) identified significant predictors for the latter namely fructose, valine, butanoic acid in NAC and cholesterol, erythrose, isoleucine in ISO models, with proline and succinic acid as common for both models. Metabolite set enrichment analysis (MSEA) of those significant predictors (p < 0.05) mapped butyrate metabolism as highly influential pathway in NAC, with arginine-proline metabolism and branched chain amino acid (BCAA) degradation as common pathways in both models, thus providing new insights towards initial metabolic remodeling in the pathogenesis of CH.

Numerous studies have investigated metabolite alterations resulting from pharmacological treatment in depression models although few quantitative studies explored metabolites exhibiting constant alterations. This study aimed to identify consistently dysregulated metabolites across such studies using a knowledgebase-driven approach. This study was based on 157 studies that identified an assembly of 2757 differential metabolites in the brain, blood, urine, liver, and feces samples of depression models with pharmacological medication. The use of a vote-counting approach to identify consistently upregulated and downregulated metabolites showed that serotonin, dopamine, norepinephrine, gamma-aminobutyric acid, anandamide, tryptophan, hypoxanthine, and 3-methoxytyramine were upregulated in the brain, while quinolinic acid, glutamic acid, 5-hydroxyindoleacetic acid, myo-inositol, lactic acid, and the kynurenine/tryptophan ratio were downregulated. Circulating levels of trimethylamine N-oxide, isoleucine, leucine, tryptophan, creatine, serotonin, valine, betaine, and low-density lipoprotein were elevated. In contrast, levels of alpha-D-glucose, lactic acid, N-acetyl glycoprotein, glutamine, beta-D-glucose, corticosterone, alanine, phenylacetylglycine, glycine, high-density lipoprotein, arachidonic acid, myo-inositol, allantoin, and taurine were decreased. Moreover, 12 metabolites in urine and nine metabolites in the liver were dysregulated after treatment. Pharmacological treatment also increased fecal levels of butyric acid, acetic acid, propionic acid, and isovaleric acid. Collectively, metabolite disturbances induced by depression were reversed by pharmacological treatment. Pharmacological medication reversed the reduction of brain neurotransmitters caused by depression, modulated disturbance of the tryptophan-kynurenine pathway and inflammatory activation, and alleviated abnormalities of amino acid metabolism, energy metabolism, lipid metabolism, and gut microbiota-derived metabolites.

Objective: D-Glucosamine (GlcN) is an important amino sugar with various applications in medicine, food & beverages, nutritional supplements, and dairy products. This study aimed to produce GlcN from N-acetyl-D-glucosamine (GlcNAc) with an efficient deacetylase, and apply different strategies to enhance GlcN production. Results: We screened a series of deacetylases that involved in the deacetylation of GlcNAc to form GlcN. A diacetylchitobiose deacetylase (TKDac) from Thermococcus kodakarensis exhibited high-efficient deacetylation activity for GlcNAc, yet mostly in the form of inclusion bodies. The soluble expression of TKDac was improved by a co-expressing molecular chaperone (groEL) and TKDac, and insertion of rare codon ATA encoding isoleucine. As such, the recombinant strain TKEL4 was constructed to express TKDac, and 48 g/L GlcN was achieved by TKDac-catalyzed deacetylation. To overcome the inhibition of byproduct (acetate), immobilized TKDac was carried out to produce GlcN from GlcNAc. The immobilized TKDac was conveniently re-used for several batches (above 8) with a 90% conversion rate. Conclusions: TKDac from T. kodakarensis was found to be an efficient deacetylase to produce GlcN. Co-expression of molecular chaperone and target protein, and insertion of rare codons were effective to improve the soluble expression of TKDac. The immobilized TKDac represents a promising method for future GlcN production.