Gerbil adrenal 11 beta- and 19-hydroxylating activities respond similarly to inhibitory or stimulatory agents: two activities of a single enzyme.
A high level of steroid 19-hydroxylation is exhibited by adrenal mitochondria of the gerbil, Meriones, unguiculatus, that accounts for the ability of that species to produce nearly equal amounts of corticosterone and 19-hydroxycorticosterone (Proc. Soc. exp. Biol. Med. 165 (1980) 69-74). Inhibitors of steroidogenesis and a polyclonal antibody against bovine cytochrome P-450(11 beta) were used to determine if the agents would effect differential or parallel suppression of 19- vs 11 beta-hydroxylation by gerbil adrenal mitochondria in vitro. The inhibitors (0.1-60 microM) tested (listed in order of decreasing effectiveness) were imazalil, metyrapone, miconazole and 4-hydroxyandrostenedione. With each inhibitor the degree of suppression of 11 beta-hydroxylation was accompanied by a parallel decline in 19-hydroxylation. The addition of the polyclonal antibody preparation also produced equivalent declines in the rates of the two hydroxylation reactions. The addition of ACTH 1 microM to primary cultures of gerbil adrenal cells brought about nearly equal increases in the secretion of 11 beta- and 19-hydroxylated steroids into the culture media. These results support the hypothesis that the 11 beta-hydroxylase of gerbil adrenal mitochondria has the capacity to carry out 11 beta- and 19-hydroxylations with nearly equal facility.
Drummond
T D
TD
Department of Biology, Southern Methodist University, Dallas, TX 75275.
Mason
J I
JI
McCarthy
J L
JL
D000302:Adrenal Cortex / Q000201:enzymology*; D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D005260:Female; D005849:Gerbillinae / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D008928:Mitochondria / Q000201:enzymology; D013045:Species Specificity; D013250:Steroid Hydroxylases / Q000378:metabolism*; D013379:Substrate Specificity
D013250:Steroid Hydroxylases