Properties of cupric ions in benzylamine oxidase from pig plasma as studied by magnetic-resonance and kinetic methods.
Benzylamine oxidase from pig plasma has been studied by a variety of chemical and physical techniques. 1. Analytical ultracentrifugation, gel electrophoresis and isoelectric-focusing studies suggest that the enzyme is composed of two subunits with closely similar primary structures. 2. E.s.r. and n.m.r. measurements show that the enzyme contains two well-separated (greater than 0.6 nm) Cu2+ ions at chemically distinct sites. Each Cu2+ ion is coordinated by two water molecules, one 'axial' and the other 'equatorial'. Both water molecules undergo fast exchange (10(5)--10(8) s-1) with solvent and are deprotonated in the pH range 8--9, but only the equatorial water molecule is displaced by the inhibitors N3- and CN-. 3. Kinetic and e.s.r. measurements show that azide and cyanide compete against O2 binding and also make the two Cu2+ sites identical. It is concluded that Cu2+ must participate in the re-oxidation of reduced enzyme by molecular O2.
D000818:Animals; D001386:Azides / Q000494:pharmacology; D001595:Benzylamine Oxidase / Q000037:antagonists & inhibitors / Q000097:blood*; D055598:Chemical Phenomena; D002621:Chemistry; D003300:Copper / Q000032:analysis*; D003486:Cyanides / Q000494:pharmacology; D004578:Electron Spin Resonance Spectroscopy; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008995:Monoamine Oxidase / Q000097:blood*; D013552:Swine
D001386:Azides; D003486:Cyanides; D003300:Copper; D001595:Benzylamine Oxidase; D008995:Monoamine Oxidase