Binding of the Coenzyme and Formation of the Transketolase Active Center

Abstract

SummaryTransketolase (TK) is a homodimer, the simplest representative of thiamine diphosphate (ThDP)-dependent enzymes. It was first ThDP-dependent enzymes the crystal structure of which has been solved and revealed the general fold for this class of enzymes and the interactions of the non-covalently bound coenzyme ThDP with the protein component. Transketolase is a convenient model to study the structure(s) of the active center and the mechanism of action of ThDP-dependent enzymes. This review summarizes the results of studies on the kinetics of the interaction of ThDP with TK from Saccharomyces cerevisae as well as the generation of the catalytically active form of the coenzyme within the holoenzyme and formation of the enzyme's active center. IUBMB Life, 57: 491 -497, 2005 Keywords Transketolase; thiamine diphosphate; functional flexibility of enzyme; nonequivalence of active centers; iminotautomeric form of thiamine diphosphate.

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