Isolation and characterization of an enzyme from sheep seminal vesicles that catalyzes the glutathione-dependent reduction of prostaglandin H2 to prostaglandin F2 alpha.

An enzyme which catalyzes the direct 2-electron reduction of prostaglandin H2 to prostaglandin F2 alpha has been purified from the microsomes of sheep seminal vesicles. This enzyme, called prostaglandin endoperoxide reductase, was found to be a monomer of 16,500 molecular mass. The activity of the enzyme was dependent on reduced glutathione, enhanced by heat-treatment, and inhibited by sulfhydryl reagents. The enzyme is not a glutathione S-transferase nor does it utilize prostaglandin D2 as a substrate, and thus is distinct from previously characterized prostaglandin F2 alpha biosynthetic enzymes. The protein also catalyzes the reduction of cumene hydroperoxide, but not hydrogen peroxide. Thus, this microsomal prostaglandin endoperoxide reductase may play an important role in the synthesis of prostaglandin F2 alpha in some tissues.