ZINC, A COMPONENT OF YEAST ALCOHOL DEHYDROGENASE

Abstract

The alcohol dehydrogenase (ADH) of yeast is a zinc metalloenzyme containing 4 moles of Zn firmly bound to one mole of protein. The activity of the enzyme is directly dependent on Zn. Enzymatic action is inhibited by dithizone, 1,10-phen-anthroline, 8-hydroxyquinoline, 8-hydroxyquinoline-5-sulfonic acid, alpha, alpha[image]-dipyridyl, and thiourea. The inhibition is reversible and probably is competitive with diphosphopyridine nucleotide (DPN). The mechanisms of the enzymatic reaction, inactivation, and reversal of inhibition have been formulated in terms of the existence of a structural metalloenzyme entity. This has been assigned the empirical formula [(ADH)Zn4] in conformity with a general scheme of notation of metalloenzyme structure. The active metalloenzyme-coenzyme complex is represented by [(ADH)Zn4](DPN)4.