Yeast alcohol dehydrogenase (EC 1.1.1.1) is able to catalyze the oxidation of acetaldehyde by NAD(+) with a concomitant formation of ethanol, at pH 8.8 and pH 7.1; the stoichiometry of aldehyde oxidation vs, ethanol formation is 2:1. This enzymatic reaction obeys the Michaelis-Menten kinetics and was characterized by a high K-M for acetaldehyde (68 mM) and a low k(cat) (2.3 s(-1)), at pH 8.8, 22 degrees C. There is no visible burst of NADH during the reaction, from pH 7.1-10.1. Therefore, we have concluded that the enzyme catalyzes an apparent dismutation of two molecules of acetaldehyde into a molecule of acetic acid and a molecule of ethanol.