Purification and properties of carotene 15,15′-dioxygenase of rabbit intestine

• Main Authors: M.R. Lakshmanan, Hansa Chansang, James A. Olson
• Format: Article
• Language: English
• Published: Elsevier 1972-07-01
• Series: Journal of Lipid Research
• Subjects: β-apo-10′-carotenol; β-carotene cleavage; 15,15′-dehydro-β-apo-10′-carotenol; retinal; thiobarbituric acid method; mammals
• Online Access: http://www.sciencedirect.com/science/article/pii/S0022227520393810

Carotene 15,15′-dioxygenase, which oxidizes carotenoids to retinal, has been purified up to 200-fold from rabbit intestine by ammonium sulfate fractionation, heat treatment, and acetone precipitation. With β-apo-10′-carotenol as the substrate, the purified enzyme has a pH optimum of 7.8, a Km, of 6.7 × 10–5 m, and a Vmax at 37°C of 9 nmoles of retinal/mg protein/hr. The purified enzyme is inhibited by ferrous ion-chelating agents such as α,α′-dipyridyl and o-phenanthroline, and by sulfhydryl-binding agents such as iodoacetamide, N-ethylmaleimide, and p-chloromercuribenzoate. The latter inhibitory effects are reversed by reduced glutathione. The cleavage of β-apo-10′-carotenol is competitively inhibited by its acetylenic analog, 15,15′-dehydro-β-apo-10′-carotenol. The enzyme is present in the intestinal mucosa of several mammals, the chicken, the tortoise, and a freshwater fish, but it is absent from cat intestinal tissue.