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This study investigated the effects of different cooking methods on non-volatile flavor (free amino acids, 5'-nucleotides, and organic acids, etc.) of Coregonus peled meat. The volatile flavor characteristics were also analyzed by electric nose and gas chromatography-ion migration spectrometry (GC-IMS). The results indicated that the content of flavor substances in C. peled meat varied significantly. The electronic tongue results indicated that the richness and umami aftertaste of roasting were significantly greater. The content of sweet free amino acids, 5'-nucleotides, and organic acids was also higher in roasting group. Electronic nose principal component analysis can distinguish C. peled meat cooked (the first two components accounted for 98.50% and 0.97%, respectively). A total of 36 volatile flavor compounds were identified among different groups, including 16 aldehydes, 7 olefine aldehydes, 6 alcohols, 4 ketones, and 3 furans. In general, roasting was recommended and gave more flavor substances in C. peled meat., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 The Authors.)

The effects of dexamethasone on adenosine 5′-triphosphatase (ATPase) activity and the intracellular Ca2+ concentration ([Ca2+]i) were investigated in acidotic mouse brain. Dexamethasone (3 mg/kg, i.p.) or vehicle was administered 3 h before decapitation ischemia, and the brain concentration of adenosine 5′-triphosphate (ATP) was determined 0.5–2 min after ischemia. The effects of dexamethasone (0.3–3 mg/kg, i.p.) on Na+,K+-activated ATPase (Na+,K+-ATPase) and Ca2+-ATPase activities were evaluated at pH 7.4 and 6.8. Changes in [Ca2+]i in an acidic medium were determined in hippocampal slices by microfluorometry using rhod-2 acetoxymethyl ester as a Ca2+ marker, and the effects of dexamethasone (240 μg/l) was evaluated. Decapitation ischemia for 0.5 and 1 min reduced the brain ATP contents to 32% and 16% of the basal level, respectively. Dexamethasone slightly suppressed the extent of the decrease in the ATP level. Although dexamethasone did not affect Na+,K+-ATPase activity at pH 7.4, the activity was suppressed by dexamethasone (3 mg/kg) to 68% at pH 6.8. The activity of Ca2+-ATPase was not affected by dexamethasone at either pH 7.4 or pH 6.8. When the pH of the medium of the brain slices was changed from 7.4 to 6.8, almost no increase in [Ca2+]i was observed in the control group. The dexamethasone treatment increased [Ca2+]i in the CA1 field and dentate gyrus immediately after induction of the acidic medium, the effect being significant after 150 s. Because anaerobic glucose metabolism in the early stage of ischemia enhances intracellular lactic acidosis, the findings may suggest a mechanism for the aggravation of ischemic neuronal damage by glucocorticoids. [Copyright &y& Elsevier]

To understand the transport mechanism of the bovine heart mitochondrial ADP/ATP carrier at the atomic level, we studied the four-dimensional features of the interaction of various purine nucleotides with the adenine nucleotide binding region (ABR) consisting of Arg151-Asp167 in the second loop facing the matrix side. After three-dimensional modeling of ABR based on the experimental results, its structural changes on interaction with purine nucleotides were examined by molecular dynamics computation at 300 K. ATP/ADP were translocated to a considerable degree from the matrix side to the inner membrane region accompanied by significant backbone conformational changes, whereas neither appreciable translocation nor a significant conformational change was observed with the untransportable nucleotides AMP/GTP. The results suggested that binding of the terminal phosphate group and the adenine ring of ATP/ADP with Arg151 and Lys162, respectively, and subsequent interaction of a phosphate group(s) other than the terminal phosphate with Lys162 triggered the expansion and subsequent contraction of the backbone conformation of ABR, leading to the translocation of ATP/ADP. Based on a simplified molecular dynamic simulation, we propose a dynamic model for the initial recognition process of ATP/ADP with the carrier. [Copyright &y& Elsevier]

In Xanthomonas campestris the genes involved in polysaccharide (xanthan) biosynthesis are located in a gene cluster (gum) of 16 kb. A Tn5 insertion mutant with a reduced slimy phenotype has been characterized. This mutant failed to produce the pentasaccharide repeating-unit of xanthan. Only three sugars were transferred to the prenyl phosphate intermediate. Several lines of evidence suggested that the lipid-associated saccharide was the trisaccharide reducing end of the pentasaccharide from the wild-type strain. This trisaccharide was built up from UDP-Glc and GDP-Man, and a glucose residue was at the reducing end, linked to an allylic prenol through a diphosphate bridge. Results from one- or two-stage reactions showed that the trisaccharide-P–P-polyprenol was the precursor of the polymer. This new polymer, a polytrisaccharide, was detected also in vivo. The transposon responsible for the mutation was located within gumK gene. Therefore, this gene encodes for the glycosyltransferase IV, which catalyses the transfer of glucuronic acid to the lipid-linked β-d-Manp-(1→3)-β-d-Glcp-(1→4)-β-d-Glcp trisaccharide. A recombinant plasmid with the whole gum cluster restored the wild type phenotype. [Copyright &y& Elsevier]

Objectives: Angiotensin II (Ang II) induces fibroblast proliferation and collagen synthesis in the myocardium, but its precise mechanisms of action in human hearts are still unknown. Therefore, we investigated whether Ang II directly affects the collagen mRNA content in the human myocardium and in isolated human cardiac fibroblasts or whether the growth factors TGFβ-1 and osteopontin are involved in this process. Methods and results I: In a first set of experiments, the direct effect of Ang II on collagen I, TGFβ-1 and osteopontin mRNA content in fresh samples of human atrial myocardium was determined by the use of a short stimulation period. After 4 h, Ang II-stimulated atrial samples gave a significantly higher expression of both TGFβ-1 (183±21% of control, p<0.05) and osteopontin mRNA (275±58%, p<0.02) than the controls. In contrast, the expression of collagen I mRNA was unchanged (95±8%). Stimulation with TGFβ-1 led to an increase in collagen I and III mRNA (127±10%, p<0.05; 140±15%, p<0.02). Methods and results II: In a second protocol, to assess the effects of longer stimulation periods, we determined the effects of Ang II and its potential mediator TGFβ-1 on collagen I, III and fibronectin mRNA expression and on proliferation of cultured human cardiac fibroblasts. Ang II caused a dose-dependent stimulation of proliferation but did not affect collagen I, III or fibronectin mRNA content after 24 h. In contrast, TGFβ-1 stimulation significantly increased collagen I and III mRNA expression (124±5% and 128±5%, p<0.002). Conclusions: In the human heart, Ang II does not directly increase collagen or fibronectin mRNA, but it does increase TGFβ-1 and osteopontin mRNA expression. Since TGFβ-1 induces collagen I and III mRNA in atrial samples and in isolated cardiac fibroblasts, it may represent a necessary mediator of the Ang II effects in the human heart. [ABSTRACT FROM PUBLISHER]

Protein neddylation is a post-translational modification which transfers the ubiquitin-like protein NEDD8 to a lysine residue of the target substrate through a three-step enzymatic cascade. The best-known substrates of neddylation are cullin family proteins, which are the core component of Cullin-RING E3 ubiquitin ligases (CRLs). Given that cullin neddylation is required for CRL activity, and CRLs control the turn-over of a variety of key signal proteins and are often abnormally activated in cancers, targeting neddylation becomes a promising approach for discovery of novel anti-cancer therapeutics. In the past decade, we have witnessed significant progress in the field of protein neddylation from preclinical target validation, to drug screening, then to the clinical trials of neddylation inhibitors. In this review, we first briefly introduced the nature of protein neddylation and the regulation of neddylation cascade, followed by a summary of all reported chemical inhibitors of neddylation enzymes. We then discussed the structure-based targeting of protein-protein interaction in neddylation cascade, and finally the available approaches for the discovery of new neddylation inhibitors. This review will provide a focused, up-to-date and yet comprehensive overview on the discovery effort of neddylation inhibitors., (© 2020 Chinese Pharmaceutical Association and Institute of Materia Medica, Chinese Academy of Medical Sciences. Production and hosting by Elsevier B.V.)

Glycogen and starch are the major carbon and energy reserve polysaccharides in nature, providing living organisms with a survival advantage. The evolution of the enzymatic machinery responsible for the biosynthesis and degradation of such polysaccharides, led the development of mechanisms to control the assembly and disassembly rate, to store and recover glucose according to cell energy demands. The tetrameric enzyme ADP-glucose pyrophosphorylase (AGPase) catalyzes and regulates the initial step in the biosynthesis of both α-polyglucans. AGPase displays cooperativity and allosteric regulation by sensing metabolites from the cell energy flux. The understanding of the allosteric signal transduction mechanisms in AGPase arises as a long-standing challenge. In this work, we disclose the cryoEM structures of the paradigmatic homotetrameric AGPase from Escherichia coli ( Ec AGPase), in complex with either positive or negative physiological allosteric regulators, fructose-1,6-bisphosphate (FBP) and AMP respectively, both at 3.0 Å resolution. Strikingly, the structures reveal that FBP binds deeply into the allosteric cleft and overlaps the AMP site. As a consequence, FBP promotes a concerted conformational switch of a regulatory loop, RL2, from a "locked" to a "free" state, modulating ATP binding and activating the enzyme. This notion is strongly supported by our complementary biophysical and bioinformatics evidence, and a careful analysis of vast enzyme kinetics data on single-point mutants of Ec AGPase. The cryoEM structures uncover the residue interaction networks (RIN) between the allosteric and the catalytic components of the enzyme, providing unique details on how the signaling information is transmitted across the tetramer, from which cooperativity emerges. Altogether, the conformational states visualized by cryoEM reveal the regulatory mechanism of Ec AGPase, laying the foundations to understand the allosteric control of bacterial glycogen biosynthesis at the molecular level of detail., Competing Interests: The authors declare no financial conflict of interest., (© 2020 The Author(s).)