Members of this family contain a cross-linked, proteinous quinone cofactor, cysteine tryptophylquinone, which is required for catalysis of the oxidative deamination of a wide range of aliphatic and aromatic amines. The domain assumes a globular secondary structure, with two short alpha-helices having many turns and bends [1].

1: Crystal structure of quinohemoprotein amine dehydrogenase from Pseudomonas putida. Identification of a novel quinone cofactor encaged by multiple thioether cross-bridges. Satoh A, Kim JK, Miyahara I, Devreese B, Vandenberghe I, Hacisalihoglu A, Okajima T, Kuroda S, Adachi O, Duine JA, Van Beeumen J, Tanizawa K, Hirotsu K; J Biol Chem. 2002;277:2830-2834. PMID:11704672