Copper amine oxidases (CAOs) are ubiquitous in nature and catalyse the oxidative
deamination of primary amines to the corresponding aldehydes. Humans have three
viable CAO genes (AOC1-3). AOC1 encodes human diamine oxidase (hDAO), which is
the frontline enzyme for histamine metabolism. hDAO is unique among CAOs in that
it has a distinct substrate preference for diamines. The structure of hDAO in
space group P2(1)2(1)2(1) with two molecules in the asymmetric unit has recently
been reported. Here, the structure of hDAO refined to 2.1 A resolution in space
group C222(1) with one molecule in the asymmetric unit is reported.
