L-Amino Acid Oxidase from Venoms

Abstract

L-Amino acid oxidase (LAAO), a flavoenzyme, is a component of many animal venoms of which the enzyme from snake venom is particularly well characterized. Since the oxidation of L-amino acids produces hydrogen peroxide, the enzyme induces toxicity. Presumably, a glycan part of the enzyme anchors the molecule to cell surface and thereby generates high concentration of hydrogen peroxide locally on cell surface leading to cytotoxicity. Depending on localization of LAAO on normal cells or unwanted cells, the enzyme may be toxic or possess therapeutic potential. The mechanism of action of the enzyme is known, and the crystal structure of snake venom LAAOs has been solved. They are structurally well-conserved enzymes. Therefore, inhibitors of the enzyme may be synthesized using the template of the substrate and features of its catalytic site. Though snake venom LAAO is viewed as toxic, several beneficial activities of the enzyme are known. The physiological actions of the enzyme are not clearly understood, e.g., some contradictory results exist on its platelet aggregation activity. This article updates present knowledge on the enzyme covering various aspects of its toxicity along with its therapeutic potential.