title: The unique substrate specificity of human AOC2, a semicarbazide-sensitive amine oxidase.
abstract: Semicarbazide-sensitive amine oxidases (SSAOs) catalyze oxidative deamination of primary amines, but the true physiological function of these enzymes is still poorly understood. Here, we have studied the functional and structural characteristics of a human cell-surface SSAO, AOC2, which is homologous to the better characterized family member, AOC3. The preferred in vitro substrates of AOC2 were found to be 2-phenylethylamine, tryptamine and p-tyramine instead of methylamine and benzylamine, the favored substrates of AOC3. Molecular modeling suggested structural differences between AOC2 and AOC3, which provide AOC2 with the capability to use the larger monoamines as substrates. Even though AOC2 mRNA was expressed in many tissues, the only tissues with detectable AOC2-like enzyme activity were found in the eye. Characterization of AOC2 will help in evaluating the contribution of this enzyme to the pathological processes attributed to the SSAO activity and in designing specific inhibitors for the individual members of the SSAO family.
authors: MediCity Research Laboratory, University of Turku, and National Institute for Health and Welfare, Tykistökatu 6, 20520 Turku, Finland.
authors: Sam
authors: S
authors: Kaitaniemi
authors: Heli
authors: H
authors: Elovaara
authors: Kirsi
authors: K
authors: Grön
authors: Heidi
authors: H
authors: Kidron
authors: Janne
authors: J
authors: Liukkonen
authors: Tiina
authors: T
authors: Salminen
authors: Marko
authors: M
authors: Salmi
authors: Sirpa
authors: S
authors: Jalkanen
authors: Kati
authors: K
authors: Elima
mesh_terms: D006631:Amine Oxidase (Copper-Containing) / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology; D015815:Cell Adhesion Molecules / Q000737:chemistry / Q000378:metabolism / Q000502:physiology; D003001:Cloning, Molecular; D019281:Dimerization; D005123:Eye / Q000378:metabolism; D005136:Eye Proteins / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology; D006801:Humans; D007700:Kinetics; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology; D010627:Phenethylamines / Q000378:metabolism; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000378:metabolism; D013379:Substrate Specificity; D014363:Tryptamines / Q000378:metabolism; D014439:Tyramine / Q000378:metabolism
chemical_list: D015815:Cell Adhesion Molecules; D005136:Eye Proteins; D010627:Phenethylamines; D012333:RNA, Messenger; D014363:Tryptamines; C029261:phenethylamine; C030820:tryptamine; C105198:AOC2 protein, human; C076668:AOC3 protein, human; D006631:Amine Oxidase (Copper-Containing); D000587:Oxidoreductases Acting on CH-NH Group Donors; D014439:Tyramine