Mechanism of 25-hydroxyvitamin D3 24-hydroxylation: incorporation of oxygen-18 into the 24 position of 25-hydroxyvitamin D3.
The oxygen enzymatically inserted as a hydroxyl function by chick kidney homogenate into the 24 position of 25-hydroxyvitamin D3 to give 24,25-dihydroxyvitamin D3 is derived exclusively from 18O2. Therefore, like the 25-hydroxyvitamin D3-lalpha-hydroxylase system, the 25-hydroxyvitamin D3-24-hydroxylase system is also a monooxygenase ("mixed-function oxidase").
D000818:Animals; D002645:Chickens; D006887:Hydroxycholecalciferols / Q000378:metabolism*; D007668:Kidney / Q000378:metabolism*; D008297:Male; D013058:Mass Spectrometry; D006899:Mixed Function Oxygenases / Q000378:metabolism*
D006887:Hydroxycholecalciferols; D006899:Mixed Function Oxygenases