title: The 1.13-A structure of iron-free cytochrome c peroxidase.
abstract: The iron-free cytochrome c peroxidase (CCP) crystal structure has been determined to 1.13 A and compared with the 1.2-A ferric-CCP structure. Quite unexpectedly, removal of the iron has no effect on porphyrin geometry and distortion, indicating that protein-porphyrin interactions and not iron coordination or formation of the axial His-Fe bond determines porphyrin conformation. However, there are changes in solvent structure in the distal pocket, which lead to changes in the distal His52 acid-base catalyst. The observed ability of His52 to move in response to small changes in solvent structure is very likely important for its role as a catalyst in assisting in the heterolytic fission of the peroxide O-O bond.
authors.affiliation: Department of Molecular Biology and Biochemistry and the Center in Chemical and Structural Biology, University of California, Irvine, CA 92697-3900, USA.
authors.forename: B
authors.initials: B
authors.lastname: Bhaskar
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Poulos
mesh_terms: D001665:Binding Sites; D018360:Crystallography, X-Ray; D003578:Cytochrome-c Peroxidase / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D007501:Iron; D011166:Porphyrins / Q000737:chemistry; D011487:Protein Conformation; D012997:Solvents / Q000737:chemistry
chemical_list: D011166:Porphyrins; D012997:Solvents; D007501:Iron; D003578:Cytochrome-c Peroxidase