STEADY-STATE KINETIC MECHANISM OF THERMOANAEROBIUM-BROCKII ALCOHOL-DEHYDROGENASE - A STUDY OF DISCRIMINATION BETWEEN ALTERNATIVE KINETIC-MODELS

Two steady-state kinetic mechanisms have been proposed for the oxidati on of 2-propanol catalyzed by Thermoanaerobium brockii alcohol dehydro genase (TBADH): the sequential ordered BiBi mechanism and the Theorell -Chance BiBi mechanism. Discrimination between these kinetic mechanism s was achieved by analyzing the inhibition produced by acetone, the fi rst product of the reaction sequence in relation to the second substra te of the enzyme (2-propanol). Two types of experimental data were use d: a data set combining initial rate experiments in the absence of pro ducts with data involving inhibition by acetone in relation to 2-propa nol as variable substrate; and, data sets just containing product inhi bition experiments by acetone with 2-propanol as variable substrate. T he results obtained strongly suggest that the kinetic mechanism of TBA DH is described by the Theorell-Chance BiBi kinetic model.