Steroid hydroxylations by human adrenal cortex microsomes 1, 2.
Microsomes were prepared from human adrenals obtained at the time of cadaveric renal transplantation. Microsomes were assayed for cytochrome P-450 concentrations (mean =0.63 nmol/mg protein) and NADPH-cytochrome c reductase activity (mean 65 nmol times min-1 times mg-1 protein). Rates of steroid hydroxylation were measured. In man, the rate of 21-hydroxylation of 17-hydroxyprogesterone was approximately three times the rate of 21-hydroxylation of progesterone. The rate of 17-hydroxylation of progesterone was approximately three times the rate of 21-hydroxylation of progesterone. Substrate binding to microsomes showed a type I spectrum with progesterone and 17-hydroxy-progesterone. Both substrates bound all spectrally identifiable sites. Antibody prepared against procine NADPH-cytochrome c reductase inhibited concomitantly human reductase, 21-hydroxylation of progesterone and 17-hydroxyprogesterone, and 17-hydroxylation of progesterone. These results were compared to previous studies with beef adrenal microsomes. No specific evidence was obtained to suggest multiple forms of 21-hydroxylase in human adrenal microsomes. It appears as though the human adrenal microsomal cytochrome P-450 electron transport chain is immunologically similar to those studied previously--beef adrenal, and rat and human liver.
D000302:Adrenal Cortex / Q000201:enzymology / Q000378:metabolism* / Q000648:ultrastructure; D000311:Adrenal Glands / Q000378:metabolism*; D001665:Binding Sites; D002625:Chemistry, Organic; D003577:Cytochrome P-450 Enzyme System / Q000032:analysis; D006801:Humans; D006900:Hydroxylation; D006908:Hydroxyprogesterones / Q000378:metabolism*; D007106:Immune Sera / Q000494:pharmacology; D008861:Microsomes / Q000032:analysis / Q000201:enzymology / Q000378:metabolism*; D009251:NADPH-Ferrihemoprotein Reductase / Q000032:analysis / Q000037:antagonists & inhibitors; D055601:Organic Chemistry Phenomena; D011374:Progesterone / Q000378:metabolism*
D006908:Hydroxyprogesterones; D007106:Immune Sera; D011374:Progesterone; D003577:Cytochrome P-450 Enzyme System; D009251:NADPH-Ferrihemoprotein Reductase