Involved in putrescine catabolism in peroxisomes (PubMed:24287136). May also be involved in the biosynthesis of pyridine alkaloid natural products, leading mainly to the production of anabasine, anatabine, nicotine and nornicotine, effective deterrents against herbivores with antiparasitic and pesticide properties (neurotoxins); nornicotine serves as the precursor in the synthesis of the carcinogen compound N'-nitrosonornicotine (NNN) (PubMed:16656744). Oxidizes preferentially non-N-methylated amines (PubMed:24287136). an aliphatic amine + H2O + O2 = an aldehyde + H2O2 + NH4(+) H2O + N-methylputrescine + O2 = 4-methylaminobutanal + H2O2 + NH4(+) Binds 1 copper ion per subunit (By similarity). Can also use zinc ion as cofactor (By similarity). Contains 1 topaquinone per subunit. Alkaloid biosynthesis; nicotine biosynthesis. Amine and polyamine degradation; putrescine degradation. Homodimer. Mainly expressed in roots, and, to a lower extent, in leaves and stems. Topaquinone (TPQ) is generated by copper-dependent autoxidation of a specific tyrosyl residue. Belongs to the copper/topaquinone oxidase family.