The Purification and Properties of NADPH-Dependent Carbonyl Reductases from Rat Ovary

Abstract

Two carbonyl reductases have been highly purified from rat ovary to apparent homogene-ity. Though they have similarities in terms of molecular weight (33, 000), substrate specificities, inhibitor sensitivities, amino acid composition, and immunological properties, they differed in pI values (6.0 and 5.9). Both enzymes reduced aromatic aldehydes, ketones, and quinones at higher rates, compared to prostaglandins and 3-ketosteroids, whereas they showed higher affinity for prostaglandins and 3-ketosteroids. The enzymes also catalyzed oxidation of the 9-hydroxy group of prostaglandin F_2α. Moreover, they showed the remarkable characteristic of catalyzing the reduction of not only the 9-keto group of prostaglandin E₂ but also the 15-keto group of 13, 14-dihydro-15-ketoprostaglandin F_2α. Both enzymes were inhibited by SH-reagents, quercitrin, indomethacin, furosemide, and disulfiram. The results of immunoinhibition, using antibody against the purified enzymes, indicated that the enzymes were solely responsible for the overall catalytic activities of prostaglandin E series reduction, as well as 13, 14-dihydro-15-ketoprostaglandin F_2α reduction and prostaglandin F_2α oxidation in rat ovarian cytosol. Western-blot analysis revealed that immunoreactive proteins were present in adrenal gland and various reproductive tissues except uterus of rats.