Flavoenzyme which catalyzes the oxidation of N(1)- acetylspermine to spermidine and is thus involved in the polyamine back-conversion (PubMed:12477380). Can also oxidize N(1)- acetylspermidine to putrescine. Substrate specificity: N(1)- acetylspermine = N(1)-acetylspermidine > N(1),N(12)-diacylspermine >> spermine. Does not oxidize spermidine. Plays an important role in the regulation of polyamine intracellular concentration and has the potential to act as a determinant of cellular sensitivity to the antitumor polyamine analogs (PubMed:12477380). . This is the function of PAOX (polyamine oxidase, ENSG00000148832).