Enzymatic properties of 13,14-dihydroprostaglandin F2 alpha synthetase in ovarian cytosol of the rat.

The activity of 13,14-dihydroprostaglandin F2 alpha (13,14 H2-PGF2 alpha) synthetase, which catalyzes the conversion of 13,14-dihydro-15-keto-PGF2 alpha (15KD-PGF2 alpha) to 13,14H2-PGF2 alpha, was examined in ovarian cytosol of rat, hamster, mouse, rabbit, guinea-pig, pig, cow and dog. The activity was very low in all species except the rat. The tissue distribution of 13,14H2-PGF2 alpha synthetase in the rat was next studied, and the highest activities were observed in the ovary and adrenal gland, whereas the activities in the lung and kidney, which possess higher activities of 15-hydroxy-PG dehydrogenase, were much lower. The bulk (80%) of the activity in the ovary was recovered in the cytosol fraction. The enzyme from rat ovarian cytosol showed two optimum pH values, at pH 7.0 and pH 8.0. The enzyme activity was strongly inhibited by sulfhydryl reagents and quercitrin, but not by phenobarbital. It is suggested that 13,14H2-PGF2 alpha synthetase in rat ovarian cytosol is a carbonyl reductase, and may be involved in drug metabolism in the female reproductive system.