17-Hydroxyprogesterone metabolism in the monkey fetal adrenal: C17-20lyase and 21-hydroxylase activities.
C17-20Lyase and 21-hydroxylase activities were measured during late gestation in the rhesus monkey (Macaca mulatta) fetal adrenal. Activities were assessed in 10,000 x g supernatants with 17-hydroxyprogesterone and NADPH as substrates. Although conversion of [14C]17-hydroxyprogesterone to [14C]androstenedione was noted, activity was often nonlinear and far less than the rate of hydroxylation which together prevented an accurate estimation of lyase rate, Km and Vmax. 21-Hydroxylase activity was characterized; the mean reaction rate was 1.6 x 10(-3) mumoles NADPH oxidized/min. x mg-1 protein with an apparent Km of 3.6 x 10(-7) M and a Vmax of 2.2 x 10(-3) mumoles/min. x mg-1 protein. These values were similar to data obtained in adrenals from adult monkeys. A relatively high level of hydroxylase activity in the fetal gland might lead to an inadequate supply of precursors for the synthesis of dehydroepiandrosterone sulfate (DHEAS) in the adrenal if it also contained 3 beta-hydroxysteroid dehydrogenase (3 beta-hsdh). However, the fact that the fetal adrenal reportedly is deficient in 3 beta-hsdh may serve to protect both DHEAS and corticoid synthesis.
D000311:Adrenal Glands / Q000201:enzymology*; D000446:Aldehyde-Lyases / Q000378:metabolism*; D000735:Androstenedione / Q000378:metabolism; D000818:Animals; D005260:Female; D006908:Hydroxyprogesterones / Q000378:metabolism*; D007700:Kinetics; D008251:Macaca / Q000196:embryology*; D008253:Macaca mulatta / Q000196:embryology*; D009249:NADP / Q000378:metabolism; D011247:Pregnancy; D013254:Steroid 17-alpha-Hydroxylase; D013255:Steroid 21-Hydroxylase / Q000378:metabolism*; D013250:Steroid Hydroxylases / Q000378:metabolism*
D006908:Hydroxyprogesterones; D000735:Androstenedione; D009249:NADP; D013250:Steroid Hydroxylases; D013255:Steroid 21-Hydroxylase; D013254:Steroid 17-alpha-Hydroxylase; D000446:Aldehyde-Lyases