| Synonyms |
17,20 lyase, 17-20 lyase, 17-alpha-hydroxylase/C17-20 lyase, 17-hydroxylase/C17,20-lyase, 17alpha-hydroxylase, 17alpha-hydroxylase-C(17,20)-lyase, 17alpha-hydroxylase-C17,20-lyase, 17alpha-hydroxylase/17,20 lyase, 17alpha-hydroxylase/17,20-lyase, 17alpha-hydroxylase/17,20-lyase cytochrome P450, 17alpha-hydroxylase/C(17,20)-lyase, 17alpha-hydroxylase/C17,20-lyase, 17alpha-hydroxyprogesterone aldolase, 17alpha-hydroxyprogesterone aldolase/17,20-lyase, 17alpha-lyase, Adrenal 17,20-lyase, aldolase, 17alpha-hydroxyprogesterone, C-17,20 lyase, C-17/C-20 lyase, C17(20) lyase, C17,20 lyase, C17,20-lyase, CYP17, CYP17A1, cytochrome P450 17, cytochrome P450 17A1, cytochrome P450 17alpha-hydroxylase/17,20-lyase, cytochrome p450 17alpha-hydroxylase/C(17,20)-lyase, cytochrome P450c17, P-45017alpha, P450 17A1, P45017alpha, P450c17, P450c17-I, steroid 17alphahydroxylase/17,20-lyase, Steroid C17(20) lyase |
| Comments |
A microsomal cytochrome P-450 (heme-thiolate) protein that catalyses two independent reactions at the same active site – the 17-hydroxylation of pregnenolone and progesterone, which is part of glucocorticoid hormones biosynthesis (EC 1.14.14.19), and the conversion of the 17-hydroxylated products via a 17,20-lyase reaction to form androstenedione and 3¦Â-hydroxyandrost-5-en-17-one, leading to sex hormone biosynthesis. The activity of this reaction is dependent on the allosteric interaction of the enzyme with cytochrome b5 without any transfer of electrons from the cytochrome [2,4]. The enzymes from different organisms differ in their substrate specificity. While the enzymes from pig, hamster, and rat accept both 17¦Á-hydroxyprogesterone and 17¦Á-hydroxypregnenolone, the enzymes from human, bovine, sheep, goat, and bison do not accept the former, and the enzyme from guinea pig does not accept the latter [1]. |
