Human Vitamin D 25-hydroxylase, CYP2R1 ELI

A cytochrome P450 monooxygenase involved in activation of vitamin D precursors.

Catalyzes hydroxylation at C-25 of both forms of vitamin D, vitamin D(2) and D(3) (calciol) (PubMed: 12867411, PubMed: 15465040, PubMed: 18511070).

Can metabolize vitamin D analogs/prodrugs 1alpha-hydroxyvitamin D(2) (doxercalciferol) and 1alpha-hydroxyvitamin D(3) (alfacalcidol) forming 25-hydroxy derivatives (PubMed: 15465040, PubMed: 18511070).

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 (CPR; NADPH-ferrihemoprotein reductase) (PubMed: 12867411, PubMed: 15465040, PubMed: 18511070).