Purification of 20 alpha-hydroxysteroid oxidoreductase from bovine fetal erythrocytes.

NADPH-dependent 20 alpha-hydroxysteroid oxidoreductase (20 alpha-HSD; EC 1.1.1.149) from bovine fetal erythrocytes was obtained for the first time free of hemoglobin by a new 2,500-fold purification scheme. This was achieved by a sequence of calcium phosphate gel absorption, ammonium sulfate fractionation, and affinity chromatography. The present results lead us to believe that the NADPH-dependent 3 beta-hydroxysteroid oxidoreductase activity, which was co-purified with 20 alpha-activity, may originate at the active site of 20 alpha-HSD (2).