title: X-ray crystal structure of the ferric sperm whale myoglobin: imidazole complex at 2.0 A resolution.
abstract: The X-ray crystal structure of the ferric sperm whale (Physeter catodon) myoglobin:imidazole complex has been refined at 2.0 A resolution, to a final R-factor of 14.8%. The overall conformation of the protein is little affected by binding of the ligand. Imidazole is co-ordinated to the heme iron at the distal site, and forces distinguishable local changes in the surrounding protein residues. His64(E7) swings out of the distal pocket and becomes substantially exposed to the solvent: nevertheless, it stabilizes the exogenous ligand by hydrogen bonding. The side-chains of residues Arg45(CD3) and Asp60(E3) are also affected by imidazole association.
authors.affiliation: Dipartimento di Genetica e Microbiologia, Università di Pavia, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Lionetti
authors.forename: M G
authors.initials: MG
authors.lastname: Guanziroli
authors.forename: F
authors.initials: F
authors.lastname: Frigerio
authors.forename: P
authors.initials: P
authors.lastname: Ascenzi
authors.forename: M
authors.initials: M
authors.lastname: Bolognesi
mesh_terms: D000818:Animals; D003461:Crystallography; D005290:Ferric Compounds / Q000737:chemistry; D006418:Heme; D007093:Imidazoles / Q000737:chemistry; D008958:Models, Molecular; D009038:Motion; D009211:Myoglobin / Q000737:chemistry / Q000648:ultrastructure*; D011487:Protein Conformation; D014907:Whales; D014961:X-Ray Diffraction
chemical_list: D005290:Ferric Compounds; D007093:Imidazoles; D009211:Myoglobin; D006418:Heme; C029899:imidazole