Membrane primary amine oxidase (AOC3, aka vascular adhesion protein 1, VAP-1) is a membrane-bound, dimeric enzyme that can catalyse the oxidative deamination of primary amines such as benzylamine (BZAM) and methyalmine to their respective aldehydes (Kaitaniemi et al. 2009, Bour et al. 2007). It is widely expressed with highest expression in peripheral lymph nodes, hepatic endothelia, appendix, lung and small intestine (Smith et al. 1998).