CHARACTERIZATION OF RAT TESTICULAR ALCOHOL DEHYDROGENASE

A protein from rat testes that catalyzes the oxidation of ethanolin the presence of NAD⁺, but not NADP⁺, has been characterizedenzymatically and compared to that of hepatic alcohol dehydrogenaseobtained from the same animals. The testicular enzyme, likethe hepatic enzyme, has a K_m value for ethanol in the 0.5–1.0-mMrange and can utilize other alcohols such as n-propanol, n-butanol,and isobutanol, although the K_m values for these other alcoholsare considerably lower (0.03–0.08 mM) that that for ethanol.The testicular enzyme is more heat-labile than is the hepaticenzyme. Finally, the testicular enzyme catalyzes the oxidationof retinol and its retinol dehydrogenase activity is inhibitedby ethanol.