Aminotransferase, L-amino acid oxidase and b-lyase reactions involving L-cysteine S-conjugates found in allium extracts Relevance to biological activity?

摘要: Abstract Several cysteine S -conjugates that occur in extracts of garlic and other plants the allium family possess anti-oxidant properties, many, including -allyl- l -cysteine (SAC) -allylmercapto- (SAMC), are promising anti-cancer agents. To understand possible biochemical mechanisms contributing to protective effects, ability selected allium-derived undergo various enzyme-catalyzed transformations was investigated. SAC, SAMC, -propylmercapto- -penta-1,3-dienylmercapto- were shown be substrates of: (a) highly purified rat kidney glutamine transaminase K (GTK); (b) snake venom -amino acid oxidase; (c) a -conjugate β-lyase present liver cytosol. -Methylmercapto- substrate GTK oxidase, but not β-lyase. Evidence is presented major enzyme responsible for reactions cytosol γ-cystathionase. The role γ-cystathionase generating sulfane sulfur from disulfide-containing extracts, this regulation, targeting cancer cells detoxification discussed. An interesting side finding work mitochondria more active than catalyzing reaction with mitochondrial protoxicant -(1,1,2,2-tetrafluoroethyl)- (TFEC) at physiological pH low concentration.