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 ...
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.
Related Citations:
Reaction of Ferrous Cytochrome C Peroxidase with Dioxygen: Site-Directed Mutagenesis Provides Evidence for Rapid Reduction of Dioxygen by Intramolecular Electron Transfer from the Compound I Radical Site Miller, M.A., Bandyopadhyay, D., Mauro, J.M., Taylor, T.G., Kraut, J. (1992) Biochemistry 31: 2789
X-Ray Structures of Recombinant Yeast Cytochrome C Peroxidase and Three Heme Cleft Mutants Prepared by Site-Directed Mutagenesis Wang, J., Mauro, J.M., Edwards, S.L., Oatley, S.J., Fishel, L.A., Ashford, V.A., Xuong, N.-H., Kraut, J. (1990) Biochemistry 29: 7160
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Organizational Affiliation:
Department of Chemistry, University of California, San Diego La Jolla 92093-0317.
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