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. Is highly active against L-Met, L-Leu, L-norleucine (L-2-aminohexanoate), L-Trp, L-Phe, moderately active against L-Tyr, and no active on L-Gly, L-Ala, L-Val, L-Pro, L-His, L-Lys, L-Arg, L-Asp, L-Asn, L-Gln, L-Glu, L-Ser, and L-Thr. Exhibits diverse biological activities, such as hemorrhage, hemolysis, edema, antibacterial and antiparasitic activities. In addition, this protein induces apoptosis. It also interacts with endothelial cells, and inhibits collagen- and ADP-induced platelet aggregation. L-LAAO family effects on platelets are controversial, since it either induces aggregation or inhibits agonist-induced aggregation. These different effects are probably due to different experimental conditions.