title: Impairment of platelet aggregation by Echis colorata venom mediated by L-amino acid oxidase or H2O2.
abstract: Echis colorata bites cause impairment of platelet aggregation and hemostatic disorders. The mechanism by which the snake venom inhibits platelet aggregation was studied. Upon fractionation, aggregation impairment activity and L-amino acid oxidase activity were similarly separated from the crude venom, unlike other venom enzymes. Preparations of L-amino acid oxidase from E. colorata and from Crotalus adamanteus replaced effectively the crude E. colorata venom in impairment of platelet aggregation. Furthermore, different treatments known to inhibit L-amino acid oxidase reduced in parallel the oxidase activity and the impairment potency of both the venom and the enzyme preparation. H2O2 mimicked characteristically the impairment effects of L-amino acid oxidase and the venom. Catalase completely abolished the impairment effects of the enzyme and the venom. It is concluded that hydrogen peroxide formed by the venom L-amino acid oxidase plays a role in affecting platelet aggregation and thus could contribute to the extended bleeding typical to persons bitten by E. colorata.
mesh_terms: D000594:Amino Acid Oxidoreductases / Q000097:blood*; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D006861:Hydrogen Peroxide / Q000097:blood*; D050830:L-Amino Acid Oxidase; D010974:Platelet Aggregation / Q000187:drug effects*; D014757:Viper Venoms / Q000494:pharmacology*
chemical_list: D014757:Viper Venoms; D006861:Hydrogen Peroxide; D000594:Amino Acid Oxidoreductases; D050830:L-Amino Acid Oxidase