Some properties of progesterone 5 alpha-reductase solubilized from rat liver microsomes.
The experiments described in this paper were undertaken to examine the requirements of NADPH-cytochrome c reductase and phosphatidylcholine for hepatic steroid 5 alpha-reduction, previously proposed by Golf and Graef (Golf, S. W. and Graef, V. (1978) J. Steroid Biochem. 9, 369-371). To determine how NADPH-cytochrome c reductase participates in hepatic 5 alpha-reductase activity, antibodies against the purified NADPH-cytochrome c reductase were added to 5 alpha-reductase preparation solubilized from rat liver microsomes. Whereas both NADPH-cytochrome c reductase and progesterone 16 alpha-hydroxylase in the preparation were inhibited by the antiserum, the inhibitory effect on 5 alpha-reductase activity was not observed. In addition, chromatography of the polyethylene glycol fraction active in 5 alpha-reduction on DEAE-cellulose resulted in the complete separation of 5 alpha-reductase activity from NADPH-cytochrome c reductase activity. Unlike NADPH-cytochrome c reductase, phosphatidylcholine increased the activity of the partially purified 5 alpha-reductase about 2.5 fold. Phosphatidylserine also enhanced the activity to an extent identical for phosphatidylcholine. Phosphatidic acid and lysophosphatidylcholine were stimulatory to lesser extents.
D000818:Animals; D000906:Antibodies / Q000276:immunology; D001667:Binding, Competitive; D002848:Chromatography, DEAE-Cellulose; D066298:In Vitro Techniques; D008862:Microsomes, Liver / Q000201:enzymology*; D009251:NADPH-Ferrihemoprotein Reductase / Q000276:immunology; D010088:Oxidoreductases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010743:Phospholipids / Q000494:pharmacology; D051381:Rats; D039181:Steroid 16-alpha-Hydroxylase
D000906:Antibodies; D010743:Phospholipids; D010088:Oxidoreductases; D039181:Steroid 16-alpha-Hydroxylase; C022447:3-oxo-5-alpha-steroid 4-dehydrogenase (NADP(+)); D009251:NADPH-Ferrihemoprotein Reductase