title: Side-on copper-nitrosyl coordination by nitrite reductase.
abstract: A copper-nitrosyl intermediate forms during the catalytic cycle of nitrite reductase, the enzyme that mediates the committed step in bacterial denitrification. The crystal structure of a type 2 copper-nitrosyl complex of nitrite reductase reveals an unprecedented side-on binding mode in which the nitrogen and oxygen atoms are nearly equidistant from the copper cofactor. Comparison of this structure with a refined nitrite-bound crystal structure explains how coordination can change between copper-oxygen and copper-nitrogen during catalysis. The side-on copper-nitrosyl in nitrite reductase expands the possibilities for nitric oxide interactions in copper proteins such as superoxide dismutase and prions.
authors.affiliation: Department of Microbiology and Immunology, The University of British Columbia, Vancouver, BC, Canada V6T 1Z3.
authors.forename: Elitza I
authors.initials: EI
authors.lastname: Tocheva
authors.forename: Federico I
authors.initials: FI
authors.lastname: Rosell
authors.forename: A Grant
authors.initials: AG
authors.lastname: Mauk
authors.forename: Michael E P
authors.initials: ME
authors.lastname: Murphy
mesh_terms: D042481:Alcaligenes faecalis / Q000201:enzymology; D001205:Ascorbic Acid / Q000378:metabolism; D001665:Binding Sites; D002384:Catalysis; D003300:Copper / Q000378:metabolism*; D003460:Crystallization; D018360:Crystallography, X-Ray; D004578:Electron Spin Resonance Spectroscopy; D006860:Hydrogen Bonding; D008956:Models, Chemical; D008958:Models, Molecular; D009569:Nitric Oxide / Q000378:metabolism*; D009572:Nitrite Reductases / Q000737:chemistry* / Q000378:metabolism*; D009573:Nitrites / Q000378:metabolism*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism
chemical_list: D009573:Nitrites; D009569:Nitric Oxide; D003300:Copper; D009572:Nitrite Reductases; D001205:Ascorbic Acid; D010100:Oxygen