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:29890640). Shows activity on L-Leu (PubMed:29890640). Exhibits diverse biological activities, such as hemorrhage, hemolysis, edema, antibacterial and antiparasitic activities, as well as regulation of platelet aggregation (By similarity). In vitro, when tested on colon cancer cells, shows inhibition of cell proliferation, and induction of apoptosis, which is probably a consequence of the increased caspase-3 activity and the decreased Bcl-2 expression (PubMed:29890640). an L-alpha-amino acid + H2O + O2 = a 2-oxocarboxylate + H2O2 + NH4(+) H2O + L-leucine + O2 = 4-methyl-2-oxopentanoate + H2O2 + NH4(+) Monomer. This is in contrast with most of its orthologs, that are non-covalently linked homodimers. Expressed by the venom gland. N-glycosylated. Belongs to the flavin monoamine oxidase family. FIG1 subfamily.