Catalyzes the oxidative deamination of primary and some secondary amines such as neurotransmitters, and exogenous amines including the tertiary amine, neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), with concomitant reduction of oxygen to hydrogen peroxide and participates in the metabolism of neuroactive and vasoactive amines in the central nervous system and peripheral tissues (PubMed:8003474). Preferentially degrades benzylamine and phenylethylamine (PubMed:8003474). a secondary aliphatic amine + H2O + O2 = a primary amine + an aldehyde + H2O2 an aliphatic amine + H2O + O2 = an aldehyde + H2O2 + NH4(+) benzylamine + H2O + O2 = benzaldehyde + H2O2 + NH4(+) (R)-adrenaline + H2O + O2 = (R)-3,4-dihydroxymandelaldehyde + H2O2 + methylamine dopamine + H2O + O2 = 3,4-dihydroxyphenylacetaldehyde + H2O2 + NH4(+) H2O + O2 + tyramine = (4-hydroxyphenyl)acetaldehyde + H2O2 + NH4(+) (R)-noradrenaline + H2O + O2 = (R)-3,4-dihydroxymandelaldehyde + H2O2 + NH4(+) 2-phenylethylamine + H2O + O2 = 2-phenylacetaldehyde + H2O2 + NH4(+) H2O + N-acetylputrescine + O2 = 4-acetamidobutanal + H2O2 + NH4(+) Monomer, homo- or heterodimer (containing two subunits of similar size). Each subunit contains a covalently bound flavin. Enzymatically active as monomer. Belongs to the flavin monoamine oxidase family.