Examination of subunit interaction in human ADH: carboxymethylation of the heterodimer beta 2 gamma 1.

Conflicting results have been obtained on whether the subunits of the human dimeric enzyme alcohol dehydrogenase interact kinetically. To examine this question, chemical modification by iodoacetate was used to selectively inactivate the beta 2 subunit of the heterodimeric isozyme beta 2 gamma 1. Subsequent studies of the modified beta 2 gamma 1 which, presumably, has only one functional active site per dimeric molecule, indicate that it is still active. Moreover, the properties of this hybrid are similar to those of the unmodified subunit. From these results, it is fair to conclude that the individual subunits of alcohol dehydrogenase contribute to the activity of the dimeric isozymes in an independent manner.