Reptile Venom L-Amino Acid Oxidases – Structure and Function

L-amino acid oxidases (LAAOs; E.C. 1.4.3.2) are flavoenzymes found in many snake venoms in varying quantities. LAAOs catalyze the stereo-specific oxidative deamination of L-amino acids to produce α-ketoacids, ammonia and hydrogen peroxide (H₂O₂). The glycan part of the LAAO anchors the molecule to the cell surface and thereby generates a high concentration of H₂O₂ locally on the cell surface, leading to cytotoxicity. Snake venom LAAOs (SV-LAAOs) exhibit substrate specificity for hydrophobic or aromatic amino acids. The percentage of SV-LAAOs in venoms can vary from 0.15% to 25%. The mechanism of action of LAAO is known, and the crystal structure of snake venom LAAOs has been solved. They are structurally well-conserved enzymes. Due to SV-LAAOs’ actions on various normal and tumor cells and their virucidal, cytotoxic, inflammatory, apoptotic and other biological effects, SV-LAAOs have become an attractive subject for studies in molecular biology, biochemistry, physiology and medicine.