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  • Title: Purification and properties of carotene 15,15'-dioxygenase of rabbit intestine.
    Author: Lakshmanan MR, Chansang H, Olson JA.
    Journal: J Lipid Res; 1972 Jul; 13(4):477-82. PubMed ID: 4625243.
    Abstract:
    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 beta-apo-10'-carotenol as the substrate, the purified enzyme has a pH optimum of 7.8, a K(m) of 6.7 x 10(-5) m, and a V(max) at 37 degrees C of 9 nmoles of retinal/mg protein/hr. The purified enzyme is inhibited by ferrous ion-chelating agents such as alpha,alpha'-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 beta-apo-10'-carotenol is competitively inhibited by its acetylenic analog, 15,15'-dehydro-beta-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.
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