Hi >So D3 is attached to a protein?! Does it lose it's properties as a > >protein after DHCC binds? Do I understand your posting correctly? >Because if it does, then passing through the stomach would effectively > >destroy its properties. H-bonds and other covalent bonds would be > >damaged and in need of repair.
Vitamin D is a fat-soluble vitamin, and it occur mainly in two forms: ergocalciferol (activated ergosterol, vitamin D2), and cholecalciferol (activated 7-dehydrocholesterol, vitamin D3). What I meant was that in the skin, previtamin D3 is synthesized by the use of UV radiation from 7-dehydrocholesterol and is slowly isomerized to vitamin D3, which is removed by vitamin D-binding protein. In the liver, vitamin D3 is converted to 25(OH)D3. It then is reabsorbed from the gut. In the kidneys, it is further hydroxylated to the metabolically active form, 1,25-dihydroxycholecalciferol (calcitriol, vitamin D hormone). Being a fat-soluble vit. it can be absorbed through the diet of reptiles as long as there is fat (fat must provide at least 10% of the total dietary calories for adequate absorption of vitamin D, at least in many mammals). And many reptiles utilizes this, although it has been suggested that many do not effectivly extract vit. D from their diet. I'm not sure if I answered your question yet, 1,25-dihydroxycholecalciferol, or calcitriol (active form of D3) does bind to a protein, and is released into the bloodstream and then transported on a carrier protein to various sites in the body. I hope this helps, and I'm sorry for being unclear on that. Magnus _________________________________________________________________ Chat with friends online, try MSN Messenger: http://messenger.msn.com ########################################################################### THE GLOBAL GECKO ASSOCIATION LISTSERV WebSite: www.gekkota.com Archive: [EMAIL PROTECTED]/ The GGA takes no responsibility for the contents of these postings. ###########################################################################
