KINETIC MECHANISM OF THE OXIDATION OF 2-PROPANOL CATALYZED BY THERMOANAEROBIUM-BROCKII ALCOHOL-DEHYDROGENASE

The reaction of oxidation of 2-propanol to acetone in the presence of NADP catalyzed by Thermoanaerobium brockii alcohol dehydrogenase (TBAD H) has been studied for gaining insight into the coupled-substrate app roach that has been extensively used for NADPH regeneration in prepara tive-scale reductions catalyzed by this enzyme. The data obtained in i nitial velocity experiments in the absence of products as well as thos e involving product inhibition and dead-end inhibition by pyrazole sug gest that the reaction mechanism is of the Theorell-Chance BiBi type a nd in which the coenzymes bind to the free form of the enzyme. The sev en kinetic parameters that characterize this kinetic model were estima ted by non-linear regression analysis using the appropriate rate equat ions. The kinetic mechanism proposed in the present work is fully comp atible with the coupled-substrate approach used for regeneration of NA DPH in reduction reactions catalyzed by TBADH.