Prostaglandin dehydrogenase activity of purified rat liver 3α-hydroxysteroid dehydrogenase

Homogeneous 3α-hydroxysteroid dehydrogenase (3α-HSD) from rat liver cytosol displays 9, 11, and 15-hydroxyprostaglandin dehydrogenase activity. Using [ 14C]-PGF 2α as substrate the products of this reaction were separated by TLC and identified by autoradiography as PGE 2 and PGB 2. The purified enzyme catalyzes this reaction at a rate 200 times faster than cytosol. This corresponds to the rate enhancement observed when the enzyme is purified from cytosol using androsterone (a 3α-hydroxysteroid) as substrate and suggests that it may represent a major 9-hydroxyprostaglandin dehydrogenase in this tissue. Although the 3α-HSD has many properties in common with the 9-hydroxyprostaglandin dehydrogenase of rat kidney, rat kidney contains no protein that is immunodetectable with polyclonal antibody raised against the purified 3α-HSD.