Regulation of Yeast Alcohol Dehydrogenase Isozymes
The two major alcohol dehydrogenases of yeast are coded by separate nuclear genes, and show 95% amino acid homology. Nonetheless, the “constitutive” ADH, ADH-I, preferentially catalyzes the reaction acetaldehyde → ethanol, and the inducible ADH, ADH-II, preferentially catalyzes the reverse reaction. Linked and non-linked mutants rendering ADH-II constitutive have been isolated by Michael Ciriacy. An understanding of the regulation of these isozymes would greatly enhance our ability to control and understand the process of fermentation, and to isolate further regulatory mutants.