Diamine oxidase [copper-containing] (DAO)

Diamine oxidase [copper-containing] (DAO, encoded by AOC1) is a copper-dependent, membrane-bound enzyme that catalyzes the oxidative deamination of biogenic diamines, most notably histamine and putrescine[1][2][3]. Each subunit contains a copper ion and a topaquinone cofactor essential for catalysis, enabling the breakdown of primary amines into aldehydes, ammonia, and hydrogen peroxide[2][3]. DAO is critical for controlling local tissue histamine levels and modulating inflammation, making it essential for normal cell growth, differentiation, and allergic regulation[1][2]. Impaired DAO activity is directly linked to histamine intolerance and can exacerbate allergic and inflammatory conditions[1][3]. Amiloride and related inhibitors can block DAO activity, which is important for therapeutic considerations and adverse drug reaction risks. Structural studies have detailed DAO’s substrate selectivity and interactions with inhibitors, supporting its role as both a therapeutic target and a biomarker in disease settings[1][2][3].

Other names

Amine oxidase copper containing 1 (AOC1)Diamine oxidase (DAO, DAO1)Amiloride-binding protein 1 (ABP, ABP1)Kidney amine oxidase (KAO, KDAO)HistaminaseAmine oxidase copper domain-containing protein 1

Enzyme inhibition: Small molecules (e.g., amiloride, imidazoles) bind the active site, blocking oxidative deamination of amine substrates (especially histamine). Competitive inhibition at the enzyme’s TPQ/copper center blocks histamine conversion.