20α,22R-Dihydroxycholesterol explained

20α,22R-Dihydroxycholesterol, or (3β)-cholest-5-ene-3,20,22-triol is an endogenous, metabolic intermediate in the biosynthesis of the steroid hormones from cholesterol.^{[1] [2]} Cholesterol ((3β)-cholest-5-en-3-ol) is hydroxylated by cholesterol side-chain cleavage enzyme (P450scc) to form 22R-hydroxycholesterol, which is subsequently hydroxylated again by P450scc to form 20α,22R-dihydroxycholesterol, and finally the bond between carbons 20 and 22 is cleaved by P450scc to form pregnenolone ((3β)-3-hydroxypregn-5-en-20-one), the precursor to the steroid hormones.

See also

• 22R-Hydroxycholesterol
• 27-Hydroxycholesterol

Notes and References

1. CHAUDHURI AC, HARADA Y, SHIMIZU K, GUT M, DORFMAN RI . Biosynthesis of pregnenolone from 22-hydroxycholesterol . The Journal of Biological Chemistry . 237 . 703–4 . March 1962 . 3 . 10.1016/S0021-9258(18)60359-X . 13878470 . free .
2. Hume R, Kelly RW, Taylor PL, Boyd GS . The catalytic cycle of cytochrome P-450scc and intermediates in the conversion of cholesterol to pregnenolone . European Journal of Biochemistry . 140 . 3 . 583–91 . May 1984 . 6723652 . 10.1111/j.1432-1033.1984.tb08142.x. free .