Catalyzes an oxidative deamination of predominantly hydrophobic and aromatic L-amino acids, thus producing hydrogen peroxide that may contribute to the diverse toxic effects of this enzyme (PubMed:11248687, PubMed:8080286). Shows high affinity for L-Phe, L-Trp, L-Met, L-Leu, and L-Ile, moderate affinity for L-Arg, L-Asp, and L-His, and very low affinity for L-Gln, L-Lys, and L-Ala (PubMed:8080286). Also shows high activity on L-norleucine (L-2-aminohexanoate), and L-norvaline (L-2-aminopentanoate) and a weak activity on L-ornithine and L-aminobutyric acid (PubMed:8080286). Also exhibits diverse biological activities, such as hemorrhage, hemolysis, edema, apoptosis of vascular endothelial cells or tumor cell lines, and antiparasitic activities, as well as regulation of platelet aggregation (By similarity). Its effect on platelets is controversial, since it either induces aggregation or inhibits agonist-induced aggregation. These different effects are probably due to different experimental conditions (By similarity). A possible explanation of high efficacy it that LAAO may bind to target cells through its sialylated glycan moiety that would bind to sialic acid-binding lectins (siglec) on target cells (PubMed:11453999). This interaction may result in production of locally high concentrations of hydrogen peroxide in or near the binding interface, leading, in turn to oxidative damage of the siglec or another adjacent cell structural elements (PubMed:11453999). an L-alpha-amino acid + H2O + O2 = a 2-oxocarboxylate + H2O2 + NH4(+) H2O + L-leucine + O2 = 4-methyl-2-oxopentanoate + H2O2 + NH4(+) H2O + L-phenylalanine + O2 = 3-phenylpyruvate + H2O2 + NH4(+) H2O + L-tryptophan + O2 = H2O2 + indole-3-pyruvate + NH4(+) H2O + L-methionine + O2 = 4-methylsulfanyl-2-oxobutanoate + H2O2 + NH4(+) H2O + L-isoleucine + O2 = (S)-3-methyl-2-oxopentanoate + H2O2 + NH4(+) H2O + L-arginine + O2 = 5-guanidino-2-oxopentanoate + H2O2 + NH4(+) H2O + L-aspartate + O2 = H2O2 + NH4(+) + oxaloacetate H2O + L-histidine + O2 = 3-(imidazol-5-yl)pyruvate + H2O2 + NH4(+) H2O + L-2-aminohexanoate + O2 = 2-oxohexanoate + H2O2 + NH4(+) H2O + L-2-aminopentanoate + O2 = 2-oxopentanoate + H2O2 + NH4(+) Optimum pH is 9.0. Thermostable. Homodimer; non-covalently linked. Expressed by the venom gland. N-glycosylated at Asn-190 and Asn-379 with bis-sialylated, biantennary, core-fucosylated dodecasaccharide (composed of N-acetylglucosamine, fucose, mannose, galactose, and sialic acid residues). Belongs to the flavin monoamine oxidase family. FIG1 subfamily.