title: Crystal structures of cyanide complexes of P450cam and the oxygenase domain of inducible nitric oxide synthase-structural models of the short-lived oxygen complexes.
abstract: The crystal structure of the ternary cyanide complex of P450cam and camphor was determined to 1.8A resolution and found to be identical with the structure of the active oxygen complex [I. Schlichting et al., 2000, Science 287, 1615]. Notably, cyanide binds in a bent mode and induces the active conformation that is characterized by the presence of two water molecules and a flip of the carbonyl of the conserved Asp251. The structure of the ternary complex of cyanide, L-arginine, and the oxygenase domain of inducible nitric oxide synthase was determined to 2.4A resolution. Cyanide binds essentially linearly, interacts with L-Arg, and induces the binding of a water molecule at the active site. This water is positioned by backbone interactions, located 2.8A from the nitrogen atom of cyanide, and could provide a proton required for O-O bond scission in the hydroxylation reaction of nitric oxide synthase.
authors.affiliation: Abt. Biophysikalische Chemie, Max Planck Institut für Molekulare Physiologie, Otto Hahn Strasse 11, 44227 Dortmund, Germany.
authors.forename: Roman
authors.initials: R
authors.lastname: Fedorov
authors.forename: Dipak K
authors.initials: DK
authors.lastname: Ghosh
authors.forename: Ilme
authors.initials: I
authors.lastname: Schlichting
mesh_terms: D000818:Animals; D001120:Arginine / Q000737:chemistry; D001224:Aspartic Acid / Q000737:chemistry; D002164:Camphor / Q000737:chemistry*; D018360:Crystallography, X-Ray; D003486:Cyanides / Q000737:chemistry; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry*; D006900:Hydroxylation; D051379:Mice; D008958:Models, Molecular; D019001:Nitric Oxide Synthase / Q000737:chemistry*; D052247:Nitric Oxide Synthase Type II; D010100:Oxygen / Q000737:chemistry / Q000378:metabolism; D010105:Oxygenases / Q000737:chemistry*; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D011522:Protons
chemical_list: D003486:Cyanides; D011522:Protons; D001224:Aspartic Acid; D002164:Camphor; D003577:Cytochrome P-450 Enzyme System; D001120:Arginine; D010105:Oxygenases; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; D010100:Oxygen