KINETIC MECHANISM OF ACTIVE-SITE NON-EQUIVALENCE IN TRANSKETOLASE

The two-step mechanism of coenzyme (TDP) binding to apotransketolase h as been examined by kinetic modeling, and the rate and equilibrium con stants for each binding step for two active sites have been determined . The dissociation constants for the primary fast binding step and the forward rate constants for the secondary slow binding step have been shown to be similar for two active sites. The backward rate constants for the secondary binding step are different for two active sites, pro viding the kinetic mechanism of their non-equivalence in TDP binding. (C) 1997 Federation of European Biochemical Societies.