title: Visualization of dioxygen bound to copper during enzyme catalysis.
abstract: X-ray crystal structures of three species related to the oxidative half of the reaction of the copper-containing quinoprotein amine oxidase from Escherichia coli have been determined. Crystals were freeze-trapped either anaerobically or aerobically after exposure to substrate, and structures were determined to resolutions between 2.1 and 2.4 angstroms. The oxidation state of the quinone cofactor was investigated by single-crystal spectrophotometry. The structures reveal the site of bound dioxygen and the proton transfer pathways involved in oxygen reduction. The quinone cofactor is regenerated from the iminoquinone intermediate by hydrolysis involving Asp383, the catalytic base in the reductive half-reaction. Product aldehyde inhibits the hydrolysis, making release of product the rate-determining step of the reaction in the crystal.
authors.affiliation: Astbury Centre for Structural Molecular Biology, School of Biochemistry and Molecular Biology, University of Leeds, Leeds LS2 9JT, UK.
authors.forename: C M
authors.initials: CM
authors.lastname: Wilmot
authors.forename: J
authors.initials: J
authors.lastname: Hajdu
authors.forename: M J
authors.initials: MJ
authors.lastname: McPherson
authors.forename: P F
authors.initials: PF
authors.lastname: Knowles
authors.forename: S E
authors.initials: SE
authors.lastname: Phillips
mesh_terms: D000332:Aerobiosis; D006631:Amine Oxidase (Copper-Containing) / Q000737:chemistry* / Q000378:metabolism*; D000693:Anaerobiosis; D001224:Aspartic Acid / Q000737:chemistry / Q000378:metabolism; D001665:Binding Sites; D002384:Catalysis; D003300:Copper / Q000378:metabolism*; D018360:Crystallography, X-Ray; D004295:Dihydroxyphenylalanine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D019281:Dimerization; D004583:Electrons; D004926:Escherichia coli / Q000201:enzymology; D006860:Hydrogen Bonding; D009569:Nitric Oxide / Q000378:metabolism; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism*; D010627:Phenethylamines / Q000378:metabolism; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D011522:Protons; D013057:Spectrum Analysis
chemical_list: C086758:2,4,5-trihydroxyphenylalanine quinone; D010627:Phenethylamines; D011522:Protons; D001224:Aspartic Acid; D009569:Nitric Oxide; C029261:phenethylamine; D004295:Dihydroxyphenylalanine; D003300:Copper; D006631:Amine Oxidase (Copper-Containing); D010100:Oxygen