Reaction mechanisms of thiamin diphosphate enzymes
نویسندگان
چکیده
منابع مشابه
Activation of thiamin diphosphate in enzymes.
Activation of the coenzyme ThDP was studied by measuring the kinetics of deprotonation at the C2 carbon of thiamin diphosphate in the enzymes pyruvate decarboxylase, transketolase, pyruvate dehydrogenase complex, pyruvate oxidase, in site-specific mutant enzymes and in enzyme complexes containing coenzyme analogues by proton/deuterium exchange detected by 1H-NMR spectroscopy. The respective dep...
متن کاملNMR analysis of covalent intermediates in thiamin diphosphate enzymes.
Enzymic catalysis proceeds via intermediates formed in the course of substrate conversion. Here, we directly detect key intermediates in thiamin diphosphate (ThDP)-dependent enzymes during catalysis using (1)H NMR spectroscopy. The quantitative analysis of the relative intermediate concentrations allows the determination of the microscopic rate constants of individual catalytic steps. As demons...
متن کاملPotent Radical-Scavenging Activities of Thiamin and Thiamin Diphosphate
Various radical-scavenging activities of thiamin and thiamin diphosphate (TDP) were found in some in vitro experiments. Thiamin and TDP caused considerable suppressive effects on superoxide generation in hypoxanthine and xanthine oxidase system which was measured by a sensitive chemiluminescence method using 2-methyl-6-[p-methylphenyl]-3,7-dihydroimidazo[1,2-alpha]pyrazin-3-one (MCLA), and thei...
متن کاملStructural Views along the Mycobacterium tuberculosis MenD Reaction Pathway Illuminate Key Aspects of Thiamin Diphosphate-Dependent Enzyme Mechanisms.
Menaquinone (MQ) is an essential component of the respiratory chains of many pathogenic organisms, including Mycobacterium tuberculosis (Mtb). The first committed step in MQ biosynthesis is catalyzed by 2-succinyl-5-enolpyruvyl-6-hydroxy-3-cyclohexadiene-1-carboxylate synthase (MenD), a thiamin diphosphate (ThDP)-dependent enzyme. Catalysis proceeds through two covalent intermediates as the sub...
متن کاملProperties and functions of the thiamin diphosphate dependent enzyme transketolase.
This review highlights recent research on the properties and functions of the enzyme transketolase, which requires thiamin diphosphate and a divalent metal ion for its activity. The transketolase-catalysed reaction is part of the pentose phosphate pathway, where transketolase appears to control the non-oxidative branch of this pathway, although the overall flux of labelled substrates remains co...
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ژورنال
عنوان ژورنال: FEBS Journal
سال: 2009
ISSN: 1742-464X,1742-4658
DOI: 10.1111/j.1742-4658.2009.06963.x