Vitamin D refers to either or both compounds.
The hydroxylases belong to a family of enzymes known as cytochrome P450 mixed function monooxydases. Three distinct parts of the enzymes, ferredoxin reductase, ferredoxin, and cytochrome P450, make an electron transport chain that ends in a heme prosthetic group bound to the cytochrome P450 subunit. Reduction of the iron ion attached to the heme molecule enables the enzymes to carry out the hydroxylation reactions. Download the FULL TEXT of this article in Acrobat PDF format. If you have not previously downloaded PDF files we suggest you access our Advice page for further information.