title: High-field EPR investigations of Mn(III)Mn(IV) and Mn(II)Mn(III) states of dimanganese catalase and related model systems.
abstract: Multi-frequency EPR experiments at 9, 34 and 94 GHz are reported on the antiferromagnetically coupled mixed valence Mn(II)Mn(III) complex of manganese catalase and on several dinuclear manganese model systems. They are compared with similar experiments obtained earlier for the Mn(III)Mn(IV) states. It is demonstrated how accurate information on the G- and 55Mn hyperfine tensors can be derived from this approach. Furthermore, the effect of oxidation state, planarity of the manganese-oxygen core and the type of ligands bridging the manganese ions on the magnetic resonance parameters and the related electronic structure is investigated. 'Broken-symmetry' density functional calculations on two Mn(III)Mn(IV) complexes, including the superoxidized state of the catalase, are presented. The agreement between calculated and experimental EPR parameters and complex geometries is remarkably good. Implications of these results for the structure and function of the dimanganese catalase are discussed.
authors.affiliation: Max-Volmer-Laboratory, Institute for Chemistry, PC 14, Technical University Berlin, D-10623 Berlin, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Teutloff
authors.forename: Kai-Oliver
authors.initials: KO
authors.lastname: Schäfer
authors.forename: Sebastian
authors.initials: S
authors.lastname: Sinnecker
authors.forename: Vladimir
authors.initials: V
authors.lastname: Barynin
authors.forename: Robert
authors.initials: R
authors.lastname: Bittl
authors.forename: Karl
authors.initials: K
authors.lastname: Wieghardt
authors.forename: Friedhelm
authors.initials: F
authors.lastname: Lendzian
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Lubitz
mesh_terms: D016880:Anisotropy; D002374:Catalase / Q000737:chemistry* / Q000378:metabolism*; D019281:Dimerization; D004578:Electron Spin Resonance Spectroscopy; D008024:Ligands; D008345:Manganese / Q000737:chemistry* / Q000378:metabolism*; D008954:Models, Biological; D008958:Models, Molecular; D010084:Oxidation-Reduction; D020836:Protein Structure, Quaternary; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism; D016963:Thermus thermophilus / Q000201:enzymology
chemical_list: D008024:Ligands; D021122:Protein Subunits; D008345:Manganese; D002374:Catalase