title: The superoxide dismutase activities of two higher valent manganese complexes, MnIV desferrioxamine and MnIII-cyclam.
abstract: A green manganese desferrioxamine complex is rapidly formed at room temperature upon stirring freshly precipitated manganese dioxide in a solution of the ligand. Spectral studies and low-temperature ESR indicate that this compound, which has been previously described as a manganese(III) complex, is better characterized as containing tetravalent manganese. The complex appears to form oligomers in solution. The extinction coefficient at 635 nm is 137 +/- 6 M-1 cm-1 (per manganese) at pH 7.8 and 88 +/- 4 M-1 s-1 at pH 6.6 after purification by chromatography. The superoxide dismutase activity was measured and compared to that of mononuclear manganese(III) 1,4,8,11-tetraazacyclodecane (cyclam). The catalytic rate constants for superoxide dismutase activity are 1.7 x 10(6) M-1 s-1 and 2.9 x 10(6) M-1 s-1 for the desferrioxamine and the cyclam complexes, respectively.
authors.affiliation: Biodynamics Institute, Louisiana State University, Baton Rouge 70803-1800.
authors.forename: J D
authors.initials: JD
authors.lastname: Rush
authors.forename: Z
authors.initials: Z
authors.lastname: Maskos
authors.forename: W H
authors.initials: WH
authors.lastname: Koppenol
mesh_terms: D003574:Cytochrome c Group / Q000378:metabolism; D003676:Deferoxamine / Q000737:chemistry / Q000378:metabolism*; D006571:Heterocyclic Compounds / Q000737:chemistry / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D046911:Macromolecular Substances; D008345:Manganese / Q000737:chemistry / Q000378:metabolism*; D013053:Spectrophotometry; D013482:Superoxide Dismutase / Q000378:metabolism*; D013481:Superoxides / Q000378:metabolism
chemical_list: D003574:Cytochrome c Group; D006571:Heterocyclic Compounds; D046911:Macromolecular Substances; D013481:Superoxides; C024560:cyclam; D008345:Manganese; D013482:Superoxide Dismutase; D003676:Deferoxamine