title: Molecular characteristics of tissue-bound semicarbazide-sensitive amine oxidase (SSAO) in guinea pig tissues.
abstract: Various mammalian tissues contain a tissue-bound amine oxidizing enzyme distinct from mitochondrial outer membrane enzyme, monoamine oxidase (MAO, EC 1.4.3.4), termed semicarbazide-sensitive amine oxidase (SSAO, EC 1.4.3.6). An increase in SSAO activity was found in patients suffering from vascular disorders such as diabetes and diabetic complications. It has previously been shown that 2-bromoethylamine (2-BEA) is a potent, and selective suicidal inhibitor of tissue-bound SSAO. The aim of this study was to investigate the interaction of this suicidal SSAO inhibitor with the tissue-bound enzyme in guinea pig lung, kidney, stomach, and heart homogenates. The conditions necessary for this inhibitor to titrate the concentrations of this enzyme were also determined. 2-BEA appears to interact with SSAO, as reported previously for this enzyme from different sources, in a manner consistent with an irreversible, "suicide" reaction. Because of this property, 2-BEA could be used to titrate the concentrations of SSAO active centers in these tissues under the appropriate conditions employed. Although some possible non-specific binding of the inhibitor to sites other than the active center of the enzyme, metabolism of this inhibitor and/or presence of enzyme subtypes was hypothesized, the molecular characteristics of SSAO in these tissues (Km, Vmax values, enzyme efficiencies, approximate enzyme concentrations, and molecular turnover numbers) towards the substrate kynuramine (0.1 mM) at pH 7.4 and 37 degrees C have been estimated.
authors.affiliation: Laboratory of Enzyme Pharmacology, Senshu University at Ishinomaki, Japan.
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Kobayashi
authors.forename: Kazuya
authors.initials: K
authors.lastname: Takahashi
authors.forename: Kaori
authors.initials: K
authors.lastname: Takayanagi
authors.forename: Kaori
authors.initials: K
authors.lastname: Takahashi
authors.forename: Shin
authors.initials: S
authors.lastname: Masuko
authors.forename: Takeshi
authors.initials: T
authors.lastname: Tadano
authors.forename: Kensuke
authors.initials: K
authors.lastname: Kisara
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Kinemuchi
mesh_terms: D006631:Amine Oxidase (Copper-Containing) / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005021:Ethylamines / Q000494:pharmacology*; D006168:Guinea Pigs; D006321:Heart / Q000187:drug effects; D007668:Kidney / Q000187:drug effects / Q000201:enzymology; D007700:Kinetics; D007735:Kynuramine / Q000378:metabolism; D008168:Lung / Q000187:drug effects / Q000201:enzymology; D008297:Male; D009206:Myocardium / Q000201:enzymology; D013270:Stomach / Q000187:drug effects / Q000201:enzymology
chemical_list: D004791:Enzyme Inhibitors; D005021:Ethylamines; C004504:2-bromoethylamine; D007735:Kynuramine; D006631:Amine Oxidase (Copper-Containing)