41 Cholesterolの側鎖切断反応について

概要

論文の詳細を見る
Biosynthesis of steroid hormones starts with the side chain cleavage of cholesterol to give pregnenolone. This reaction is catalyzed with cytochrome P-450_<scc> (cholesterol C-20,22 lyase) and requires 3 moles of O_2 and 3 moles of NADPH. The potential intermediates of this reaction were chemically synthesized and incubated with cytochrome P-450_<scc>. Pregnenolone formed was quantitatively analyzed by mass fragmentography. None of the four stereoisomers of 20,22-epoxycholesterol nor (E)-20(22)-dehydrocholesterol were significantly converted to pregnenolone. Among the stereoisomers of hydroxycholesterols, (20S)-20-, (22R)-22-, (22S)-22-hydroxycholesterols and (20R,22R)-20,22- and (20R,22S)-20,22-dihydroxycholesterols were efficiently converted to pregnenolone. Relative yields to pregnenolone from these hydroxycholesterols, together with their successful identification in the incubation medium of cholesterol suggests the major pathway: cholesterol→(20S)-20- and/or (22R)-22-hydroxycholesterols →(20R,22R)-20,22-dihydroxycholesterol→Pregnenolone.
天然有機化合物討論会の論文
1976-09-20