Copper amine oxidases catalyse the oxidative deamination of primary amines to the corresponding aldehydes, while reducing molecular oxygen to hydrogen peroxide. These enzymes are dimers of identical subunits, each comprising four domains. The N-terminal domain, which is absent in some amine oxidases, consists of a five-stranded antiparallel beta sheet twisted around an alpha helix. The D1 domains from the two subunits comprise the 'stalk' of the mushroom-shaped dimer, and interact with each other but do not pack tightly against each other [1,2].

1: Crystal structure of a quinoenzyme: copper amine oxidase of Escherichia coli at 2 A resolution. Parsons MR, Convery MA, Wilmot CM, Yadav KD, Blakeley V, Corner AS, Phillips SE, McPherson MJ, Knowles PF; Structure 1995;3:1171-1184. PMID:8591028

2: Visualization of dioxygen bound to copper during enzyme catalysis. Wilmot CM, Hajdu J, McPherson MJ, Knowles PF, Phillips SE; Science 1999;286:1724-1728. PMID:10576737