title: Xanthine oxidase catalyzes the oxidation of retinol.
abstract: In mammals, xanthine oxidase (E.C. 1.17.3.2) catalyzes the hydroxylation of a wide variety of heterocyclic substrates such as purines, pyrimidines, and pterins, in addition to aldehydes [1] as all-trans-retinaldehyde [2-5]. Here, we show that buttermilk xanthine oxidase was capable to oxidizing all-trans-retinol (t-ROL) to all-trans-retinaldehyde (t-RAL) that was successively oxidized to all-trans-retinoic acid (t-RA). A rise in the enzyme activity, when t-ROL-CRBP complex was assayed, with respect to the free t-ROL, was observed. Furthermore, treatment of the enzyme with Na2S and glutathione resulted in a significant increment in catalytic activity toward t-ROL and t-RAL, due to the reconstitution of the native structural organization of the molybdenum centre of molybdopterin cofactor of the desulfo form of xanthine oxidase.
authors.affiliation: Dipartimento di Oncologia Sperimentale e Applicazioni Cliniche, Università di Palermo, Via del Vespro 129, 90127 Palermo, Italy. gtaibi@unipa.it
authors.forename: Gennaro
authors.initials: G
authors.lastname: Taibi
authors.forename: Concetta M A
authors.initials: CM
authors.lastname: Nicotra
mesh_terms: D002384:Catalysis; D000431:Ethanol / Q000737:chemistry; D006801:Humans; D006900:Hydroxylation; D019271:Hypoxanthine / Q000737:chemistry; D007700:Kinetics; D008024:Ligands; D010100:Oxygen / Q000737:chemistry* / Q000378:metabolism; D018168:Receptors, Retinoic Acid / Q000502:physiology; D012176:Retinoids / Q000737:chemistry; D012177:Retinol-Binding Proteins / Q000737:chemistry; D054840:Retinol-Binding Proteins, Cellular; D014212:Tretinoin / Q000378:metabolism; D014801:Vitamin A / Q000737:chemistry*; D014969:Xanthine Oxidase / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D008024:Ligands; C518456:RBP1 protein, human; D018168:Receptors, Retinoic Acid; D012176:Retinoids; D012177:Retinol-Binding Proteins; D054840:Retinol-Binding Proteins, Cellular; C082927:retinoic acid binding protein I, cellular; D014801:Vitamin A; D019271:Hypoxanthine; D000431:Ethanol; D014212:Tretinoin; D014969:Xanthine Oxidase; D010100:Oxygen