Human Cytochrome P450 3A5, CYP3A5 ELI

A cytochrome P450 monooxygenase involved in the metabolism of steroid hormones and vitamins (PubMed: 2732228, PubMed: 10681376, PubMed: 11093772, PubMed: 12865317).

Mechanistically, uses molecular oxygen inserting one oxygen atom into a substrate, and reducing the second into a water molecule, with two electrons provided by NADPH via cytochrome P450 reductase (NADPH--hemoprotein reductase).

Catalyzes the hydroxylation of carbon-hydrogen bonds (PubMed: 12865317, PubMed: 2732228, PubMed: 10681376, PubMed: 11093772).

Exhibits high catalytic activity for the formation of catechol estrogens from 17beta-estradiol (E2) and estrone (E1), namely 2-hydroxy E1 and E2 (PubMed: 12865317).

Catalyzes 6beta-hydroxylation of the steroid hormones testosterone, progesterone, and androstenedione (PubMed: 2732228).

Catalyzes the oxidative conversion of all-trans-retinol to all-trans-retinal, a rate-limiting step for the biosynthesis of all-trans-retinoic acid (atRA) (PubMed: 10681376).

Further metabolizes all trans-retinoic acid (atRA) to 4-hydroxyretinoate and may play a role in hepatic atRA clearance (PubMed: 11093772).

Also involved in the oxidative metabolism of xenobiotics, including calcium Channel blocking drug nifedipine and immunosuppressive drug cyclosporine (PubMed: 2732228).