7-dehydrocholesterol

In the skin 7-dehydrocholesterol (sometimes known as provitamin D3) is synthesized from cholesterol. In the presence of ultraviolet light, it is converted to previtamin D3 which is then isomerized into vitamin D3 (cholecalciferol). An enzyme then converts vitamin D3 to its active form calcitriol.

See also:

• cholesterol

External links:

• http://www.umich.edu/~biophys/faculty/sension/
• http://www.merck.com/pubs/mmanual/section1/chapter3/3d.htm
• PREVITAMIN D CONFORMATIONS AND ESTIMATION ON THEIR ROLE IN THE WAVELENGTH DEPENDENCE OF PREVITAMIN D PHOTOSYNTHESIS IN VITRO