Purification and properties of two multiple forms of dihydrodiol dehydrogenase from guinea-pig testis

Abstract

NADP + -dependent dihydrodiol dehydrogenase ( trans-1,2-dihydrobenzene-1,2-diol: NADP + oxidoreductase, EC 1.3.1.20) activity in the cytosol of guinea-pig testis was separated into two major and two minor peaks by Q-Sepharose chromatography; one minor form was immunologically cross-reacted with hepatic aldehyde reductase. The two major enzyme forms were purified to homogeneity. One form, which had the highest amount in the tissue, was a monomeric protein with a molecular weight of 32 000 and isoelectric point of 4.2, showed strict specificity for benzene dihydrodiol and NADP +, and reduced pyridine aldehydes, glyceraldehyde and diacetyl at low rates. Another form, with a molecular weight of 36 000 and isoelectric point of 5.0, oxidized n-butanol, glycerol and sorbitol as well as benzene dihydrodiol in the presence of NADP + or NAD +, and exhibited much higher reductase activity towards various aldehydes, aldoses and diacetyl. The p I 5.0 form was more sensitive to inhibition by sorbinil and p-chloromercuriphenyl sulfonate than the p I 4.2 forms and was activated by sulfate ion. The two enzymes did not catalyze the oxidation of hydroxysteroids and xenobiotic alicyclic alcohols and were immunologically different from hepatic 17β-hydroxysteroid-dihydrodiol dehydrogenase. The results indicate that guinea-pig testis contains at least two dihydrodiol dehydrogenase distinct from the hepatic enzymes, one of which, the p I 5.0 enzymes form, may be identical to aldose reductase.