AN ATYPICAL HUMAN ALCOHOL DEHYDROGENASE

An atypical alcohol dehydrogenase was found in two human livers. The anomalous enzyme, which has been purified, differs from the normal regarding (a) pH rate profile, (b) substrate specificity, and (c) sensitivity to metal binding agents. Thiourea inhibits the variant enzyme, but activates normal human liver alcohol dehydrogenase. A simple screening test is described to differentiate between atypical and normal alcohol dehydrogenase in liver homogenate. Total alcohol dehydrogenase activity was considerably higher in livers containing the atypical enzyme.