has participant water dioxygen hydrogen peroxide imidazole-4-acetaldehyde ammonium histaminium diamine oxidase activity histamine oxidase activity https://github.com/geneontology/go-ontology/issues/28199 KEGG_REACTION:R02150 RHEA:25625 molecular_function 1H-Imidazole-4-ethanamine oxidase activity Catalysis of the reaction: H2O + histamine + O2 = H2O2 + imidazole-4-acetaldehyde + NH4+. MetaCyc:RXN-9600 GO:0052598 Reactome:R-HSA-5696131 1H-Imidazole-4-ethanamine:oxygen oxidoreductase (deaminating) activity EC:1.4.3.22