Involved in putrescine catabolism in peroxisomes (PubMed:24287136). Copper amine oxidase that can use putrescine and spermidine as substrates (PubMed:23915037). an aliphatic amine + H2O + O2 = an aldehyde + H2O2 + NH4(+) Binds 1 copper ion per subunit (By similarity). Can also use zinc ion as cofactor (By similarity). Contains 1 topaquinone per subunit. Amine and polyamine degradation; putrescine degradation. Homodimer. Mostly expressed in flowers, and, at lower levels, in stems and leaves. Accumulates during aging. Induced by salicylic acid (SA), jasmonic acid (MeJA), wounding, flagellin 22 (fgl22) and abcisic acid (ABA). Topaquinone (TPQ) is generated by copper-dependent autoxidation of a specific tyrosyl residue. Belongs to the copper/topaquinone oxidase family. Truncated N-terminus.