The crystal structure of Escherichia coli nitrate reductase A (NarGHI) in complex with pentachlorophenol has been determined to 2.0 A of resolution. We have shown that pentachlorophenol is a potent inhibitor of quinol:nitrate oxidoreductase activity and that it also perturbs the EPR spectrum of one of the hemes located in the membrane anchoring subunit (NarI). This new structural information to...

The biosynthesis of histidine, studied in most complete detail in Salmonella typhimurium with both genetic and biochemical techniques, has been reviewed recently (I, 2). The final step in this pathway, oxidation of the amino alcohol, histidinol, to histidine, was first described enzymatically in an Arthrobacter species and Escherichia coli (3)) and in yeast (4). Two oxidation steps are involved...

Hydrogen peroxide is a cell signaling agent that inactivates protein tyrosine phosphatases (PTPs) via oxidation of their catalytic cysteine residue. PTPs are inactivated rapidly during H(2)O(2)-mediated cellular signal transduction processes, but, paradoxically, hydrogen peroxide is a rather sluggish PTP inactivator in vitro. Here we present evidence that the biological buffer bicarbonate/CO(2)...

Herein we report a study combining metabolomics and mass isotopomer analysis used for investigation of the biochemical fate of γ-hydroxybutyric acid (GHB). Using various (13)C incorporation labeling patterns into GHB, we have discovered that GHB is catabolized by previously unknown processes that include (i) direct β-oxidation to acetyl-CoA and glycolate, (ii) α-oxidation to 3-hydroxypropionyl-...

The effect of aqueous solutions of ascorbic acid (AA) on the rancidity development in Cobia (Rachycentron canadum) fillets during frozen storage was studied. Cobia fillets were treated with ascorbic acid (AA 0.25% and AA 0.5%) then stored at -18°C up to 6 months. Rancidity development was measured by several biochemical indices including free fatty acids (FFA), peroxide value (PV), an...

AimStudy was undertaken to investigate the effect of altered behavioral condition like depression on various oxidative stress markers and biochemical parameters in rats. MethodsRats were subjected for short (21 days) and long term (84 days) social isolation; the rats displayed an increase in depression on force swim test relative to control. Various markers of oxidative stress like lipid per ox...

Laccases are members of a large family of multicopper oxidases that catalyze the oxidation of a wide range of organic and inorganic substrates accompanied by the reduction of dioxygen to water. These enzymes contain four Cu atoms per molecule organized into three sites: T1, T2 and T3. In all laccases, the T1 copper ion is coordinated by two histidines and one cysteine in the equatorial plane an...

The genetic and biochemical basis of perchlorate-dependent H2S oxidation (PSOX) was investigated in the dissimilatory perchlorate-reducing microorganism (DPRM) Azospira suillum PS (PS). Previously, it was shown that all known DPRMs innately oxidize H2S, producing elemental sulfur (So). Although the process involving PSOX is thermodynamically favorable (ΔG°' = -206 kJ ⋅ mol-1 H2S), the underlyin...

RS-4-(4-hydroxyphenyl)-2-butanol (rhododendrol (RD))-a skin-whitening ingredient-was reported to induce leukoderma in some consumers. We have examined the biochemical basis of the RD-induced leukoderma by elucidating the metabolic fate of RD in the course of tyrosinase-catalyzed oxidation. We found that the oxidation of racemic RD by mushroom tyrosinase rapidly produces RD-quinone, which gives ...