title: 2.2 A structure of oxy-peroxidase as a model for the transient enzyme: peroxide complex.
abstract: The Fe+3-OOH complex of peroxidases has a very short half life, and its structure cannot be determined by conventional methods. The Fe+2-O2 complex provides a useful structural model for this intermediate, as it differs by only one electron and one proton from the transient Fe+3-OOH complex. We therefore determined the crystal structure of the Fe+2-O2 complex formed by a yeast cytochrome c peroxidase mutant with Trp 191 replaced by Phe. The refined structure shows that dioxygen can form a hydrogen bond with the conserved distal His residue, but not with the conserved distal Arg residue. When the transient Fe+3-OOH complex is modelled in a similar orientation, the active site of peroxidase appears to be optimized for catalysing proton transfer between the vicinal oxygen atoms of the peroxy-anion.
authors.affiliation: Department of Chemistry, University of California, San Diego La Jolla 92093-0317.
authors.forename: M A
authors.initials: MA
authors.lastname: Miller
authors.forename: A
authors.initials: A
authors.lastname: Shaw
authors.forename: J
authors.initials: J
authors.lastname: Kraut
mesh_terms: D001665:Binding Sites; D002384:Catalysis; D018360:Crystallography, X-Ray; D003578:Cytochrome-c Peroxidase / Q000737:chemistry* / Q000235:genetics; D004583:Electrons; D005656:Fungal Proteins / Q000737:chemistry* / Q000235:genetics; D006639:Histidine / Q000737:chemistry; D006860:Hydrogen Bonding; D007501:Iron / Q000737:chemistry*; D008024:Ligands; D008958:Models, Molecular; D009211:Myoglobin / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry*; D011485:Protein Binding; D011487:Protein Conformation; D011522:Protons; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics
chemical_list: D005656:Fungal Proteins; D008024:Ligands; D009211:Myoglobin; D011522:Protons; D006639:Histidine; D007501:Iron; D003578:Cytochrome-c Peroxidase; D010100:Oxygen