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 (TBADH) has been studied for gaining insight into the coupled-substrate approach that has been extensively used for NADPH regeneration in preparative-scale reductions catalyzed by this enzyme. The data obtained in initial velocity experiments in the absence of products as well as those involving product inhibition and dead-end inhibition by pyrazole suggest that the reaction mechanism is of the Theorell-Chance BiBi type and in which the coenzymes bind to the free form of the enzyme. The seven kinetic parameters that characterize this kinetic model were estimated by non-linear regression analysis using the appropriate rate equations. The kinetic mechanism proposed in the present work is fully compatible with the coupled-substrate approach used for regeneration of NADPH in reduction reactions catalyzed by TBADH.