3 beta-Hydroxysteroid dehydrogenase in human placental microsomes and mitochondria: co-solubilization of androstene and pregnene activities.
3 beta-Hydroxysteroid dehydrogenase (3 beta-HSD) was solubilized from human term-placental microsomes and mitochondria using the non-ionic detergent, polyoxyethylene 20 cetyl ether (BrijR-58). Electron photomicrographs showed microsomes and mitochondria well disrupted by the detergent. The pregnene (C-21) and androstene (C-19) activities co-solubilized over a range (0.04-0.44) of BrijR-58/protein (B/P) concentration ratios (w/w). Optimal solubilization of the C-19 and C-21 activities were 63.3 +/- 2.6% (mean +/- SEM) from mitochondria (B/P ratio 0.37) and 71.8 +/- 2.1% from microsomes (B/P ratio 0.34). Detergent treatment of microsomes and mitochondria--varying time (5-90 min, pH 7.4) or varying pH (6.0-7.8, 90 min)--yielded C-19 activities identical with C-21 activities. The C-21/C-19 specific activity ratios of 3 beta-HSD in particulate, solubilized and chromatographed preparations were 2.28 +/- 0.16 (mean +/- SEM) for mitochondria and 1.97 +/- 0.07 for microsomes. 3 beta-HSD molecular weight estimates were 208,000 (microsomes) and 220,000 (mitochondria). These studies argue that a single protein is responsible for both the C-19 and C-21 activities of 3 beta-HSD and that this protein is the same in microsomes and mitochondria.
D015096:3-Hydroxysteroid Dehydrogenases / Q000302:isolation & purification*; D000736:Androstenes / Q000378:metabolism*; D002850:Chromatography, Gel; D004795:Enzyme Stability; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008854:Microscopy, Electron; D008861:Microsomes / Q000201:enzymology*; D008928:Mitochondria / Q000201:enzymology*; D008970:Molecular Weight; D010920:Placenta / Q000201:enzymology*; D011092:Polyethylene Glycols; D011247:Pregnancy; D011283:Pregnenes / Q000378:metabolism*; D012995:Solubility
D000736:Androstenes; D011283:Pregnenes; D011092:Polyethylene Glycols; D015096:3-Hydroxysteroid Dehydrogenases