Carboxymethylated liver alcohol dehydrogenase: pH dependence of hydride transfer during ethanol oxidation.

The rate constant for the hydride transfer step during oxidation of ethanol by carboxymethylated alcohol dehydrogenase (alcohol: NAD+ oxidoreductase, EC 1.1.1.1) is dependent on a group with pKa 7.5. This pKa is higher than that for the native enzyme. A mechanism is proposed to account for the ionisation and the protein fluorescence change which occur during formation of the carboxymethylated enzyme-NAD+-ethanol complex.