4315 17a-Hydroxypregnenolone 17a-Hydroxypregnenolone is a 21-carbon steroid that is converted from pregnenolone by cytochrome P450 17alpha hydroxylase/C17,20 lyase (CYP17, EC 1.14.99.9). 17a-Hydroxypregnenolone is an intermediate in the delta-5 pathway of biosynthesis of gonadal steroid hormones and the adrenal corticosteroids. The first, rate-limiting and hormonally regulated step in the biosynthesis of all steroid hormones is the conversion of cholesterol to pregnenolone. The conversion of cholesterol to pregnenolone is accomplished by the cleavage of the cholesterol side chain, catalyzed by a mitochondrial cytochrome P450 enzyme termed P450scc where scc designates Side Chain Cleavage. All steroid hormones are made from the pregnenolone produced by P450scc; thus, the presence or absence of each of the activities of CYP17 directs this pregnenolone towards its final metabolic pathway. While all cytochrome P450 enzymes can catalyze multiple reactions on a single active site, CYP17 is the only one described to date in which these multiple activities are differentially regulated by a physiologic process. 17a-Hydroxypregnenolone is converted to dehydroepiandrosterone by the 17,20 lyase activity of CYP17. The ratio of the 17,20 lyase to 17 alpha-hydroxylase activity of CYP17 determines the ratio of C21 to C19 steroids produced. This ratio is regulated post-translationally by at least three factors: the abundance of the electron-donating protein P450 oxidoreductase, the presence of cytochrome b5, and the serine phosphorylation of CYP17. (A3351). 387-79-1 91451 C21H32O3 White powder. 266 - 271°C No indication of carcinogenicity to humans (not listed by IARC). This is an endogenously produced metabolite found in the human body. It is used in metabolic reactions, catabolic reactions or waste generation. 2014-08-29T06:09:26Z 2016-11-09T01:09:05Z 17-Hydroxypregnenolone C05138 28750 true [H][C@@]12CC[C@](O)(C(C)=O)[C@@]1(C)CC[C@@]1([H])[C@@]2([H])CC=C2C[C@@H](O)CC[C@]12C C21H32O3 InChI=1S/C21H32O3/c1-13(22)21(24)11-8-18-16-5-4-14-12-15(23)6-9-19(14,2)17(16)7-10-20(18,21)3/h4,15-18,23-24H,5-12H2,1-3H3/t15-,16+,17-,18-,19-,20-,21-/m0/s1 JERGUCIJOXJXHF-TVWVXWENSA-N 332.477 332.23514489 Endogenous Solid HMDB00363 CHEMBL408706 82579 Kaspar, Emanuel; Hiersemann, Wolfgang; Schenck, Martin. Preparation from their esters of steroid alcohols that are sensitive to acids and alkali. (1958), DE 1028572 19580424 CAN 54:74845 AN 1960:74845 CAPLUS CHEM003221 1-[(1S,2R,5S,10R,11S,14R,15S)-5,14-dihydroxy-2,15-dimethyltetracyclo[8.7.0.0^{2,7}.0^{11,15}]heptadec-7-en-14-yl]ethan-1-one