title: [Ketometabolite of vitamine A, its structure and enzymatic transformation].
abstract: The structure and enzymatic transformations of vitamin A keto-metabolite isolated from the rat liver were investigated. With the aid of physico-chemical methods, using isotopes 3/ and 18O, PMR and mass-spectrometry it was demonstrated that the metabolite was an ester of 4-keto-retinol with palmitic acid. The structure of 4-keto-retinal was confirmed by the chemical synthesis and by the enzymatic production of its derivatives. Under the influence of alcohol dehydrogenase 4-keto-retinol in the presence of NAD transformed into 4-keto-retinal which was oxidized into 4-keto-retinoic acid with the participation ofaldehyde oxidase. Similar oxidative enzymatic transformations occurred with the reduced form of the metabolite--4-hydroxyretinol. All the products were characterized in detail. Metabolism of 4-keto-retinyl-palmitate in vivo is realized via the same pathway as metabolism of retinyl-palmitate. The general pattern of oxidation of beta-ionone ring in position 4 of vitamin A and carotenoids is discussed.
mesh_terms: D000429:Alcohol Oxidoreductases; D000445:Aldehyde Oxidoreductases; D000818:Animals; D001711:Biotransformation; D002384:Catalysis; D055598:Chemical Phenomena; D002621:Chemistry; D004578:Electron Spin Resonance Spectroscopy; D008099:Liver / Q000378:metabolism*; D013058:Mass Spectrometry; D051381:Rats; D013056:Spectrophotometry, Ultraviolet; D014801:Vitamin A / Q000031:analogs & derivatives / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D014801:Vitamin A; D000429:Alcohol Oxidoreductases; D000445:Aldehyde Oxidoreductases
vernacular_title: Ketometabolit vitamina A, ego struktura i énzimaticheskie prevrashcheniia