title: Estradiol 17 beta-dehydrogenase and 20 alpha-hydroxysteroid dehydrogenase from human placental cytosol: one enzyme with two activities?
abstract: The soluble enzyme estradiol 17 beta-dehydrogenase (17 beta-ED) from human term placental cytosol is reported to be a stereospecific oxidoreductase for estrogen substrates. A published purification scheme (heat treatment and affinity chromatography) yielded a homogeneous protein which had the reported characteristics of pure 17 beta-ED and also had 20 alpha-hydroxysteroid dehydrogenase (20 alpha-HSD) activity. Spectrophotometric assay when the buffer contained albumin, 8 mg/ml, masked the 20 alpha-HSD activity observed in albumin-free conditions and may explain why this bifunctional activity has gone unrecognized. In human placenta, one enzyme may catalyze stereospecific oxidation/reduction of both estrogen and progesterone.
mesh_terms: D015067:17-Hydroxysteroid Dehydrogenases / Q000302:isolation & purification*; D015089:20-Hydroxysteroid Dehydrogenases / Q000302:isolation & purification* / Q000378:metabolism; D003600:Cytosol / Q000201:enzymology; D004960:Estradiol Dehydrogenases / Q000302:isolation & purification* / Q000378:metabolism; D005260:Female; D006801:Humans; D010920:Placenta / Q000201:enzymology*; D013056:Spectrophotometry, Ultraviolet / Q000379:methods
chemical_list: D015067:17-Hydroxysteroid Dehydrogenases; D015089:20-Hydroxysteroid Dehydrogenases; D004960:Estradiol Dehydrogenases