Biosynthesis of Vitamin A with Rat Intestinal Enzymes

See allHide authors and affiliations

Science  20 Aug 1965:
Vol. 149, Issue 3686, pp. 879-880
DOI: 10.1126/science.149.3686.879


Vitamin A is synthesized from β-carotene in cell-free homogenates of rat intestinal mucosa, the biosynthetic enzymatic activity being present in the soluble protein fraction of the homogenate. Also required are a heat-stable factor in the particulate fraction, molecular oxygen, and bile salts. The reaction is stimulated by glutathione. The product, obtained in yields of up to 50 percent, has been identified as vitamin A aldehyde (retinal) by way of its semicarbazone derivative. The reaction mechanism involves the central cleavage of β-carotene into two molecules of retinal.