Activation of thiamin diphosphate in enzymes
| Autor: | Kai Tittmann, Gunther Kern, Margrit Killenberg-Jabs, Gunter Schneider, Jörg Schäffner, Michael Spinka, Gerhard Hübner, Christer Wikner, Holger Neef, Dorothee Kern, Sandro Ghisla |
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| Předmět: |
Stereochemistry
Pyruvate Oxidase Allosteric regulation Biophysics Pyruvate Dehydrogenase Complex Transketolase Biochemistry Cofactor Deprotonation Allosteric Regulation Structural Biology Yeasts ddc:570 Escherichia coli Pyruvate oxidase Thiamin diphosphate Nuclear Magnetic Resonance Biomolecular Molecular Biology chemistry.chemical_classification biology Pyruvate dehydrogenase complex Kinetics Lactobacillus Enzyme chemistry Pyruvate dehydrogenase multienzyme complex biology.protein Thiamine Pyrophosphate Pyruvate decarboxylase Pyruvate Decarboxylase Regulation |
| Zdroj: | Europe PubMed Central |
| Popis: | 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 deprotonation rate constant is above the catalytic constant in all enzymes investigated. The fast deprotonation requires the presence of an activator in pyruvate decarboxylase from yeast, showing the allosteric regulation of this enzyme to be accomplished by an increase in the C2-H dissociation rate of the enzyme-bound thiamin diphosphate. The data of the thiamin diphosphate analogues and of the mutant enzymes show the N1′ atom and the 4′-NH2 group to be essential for the activation of the coenzyme and a conserved glutamate involved in the proton abstraction mechanism of the enzyme-bound thiamin diphosphate. |
| Databáze: | OpenAIRE |
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