The role of zinc in alcohol dehydrogenases. II. The kinetics of the instantaneous reversible inhibition of yeast alcohol dehydrogenase by 1,10-phenanthroline.

The inhibition of yeast alcohol dehydrogenasel activity produced by 1, lo-phenanthroline, a zinc-binding reagent, has been studied intensively as an example of the action of a chelating agent on a metalloenzyme. The data (l-3) indicate that OP brings about two distinct types of inactivation of YADH: (a) an instantaneous2 and reversible inhibition and (b) a time-dependent and irreversible inhibition. The present report describes the features of the instantaneous type, whereas the kinetics of the time-dependent inhibition are the subject of a separate communication (4). The velocity constants of a sequence of postulated enzymatic reaction steps which seem consistent with the data have been determined.