Steroid Hydroxylations by Human Adrenal Cortex Microsomes1 , 2
- 1 July 1975
- journal article
- other
- Published by The Endocrine Society in Journal of Clinical Endocrinology & Metabolism
- Vol. 41 (1) , 7-12
- https://doi.org/10.1210/jcem-41-1-7
Abstract
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 × min−1 × 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-hydroxyprogesterone. Both substrates bound all spectrally identifiable sites. Antibody prepared against porcine 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.Keywords
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