title: Catalytic activity of a copper(II)-oxidized glutathione complex on aqueous superoxide ion dismutation.
abstract: The study of the catalytic activity of a Cu(II)-oxidized glutathione system upon the disproportionation of superoxide radicals shows that the mononuclear complex MA catalyzes dismutation in the pH range 7-9. The corresponding first-order rate constant of value kcat congruent to 6 X 10(6) M-1 sec-1 is pH independent, whereas the second-order rate constant ks for the reference solutions is pH dependent. The kcat constant is about 10-, 100-, and 300-fold higher than the ks constant at pH 7, 8, and 9, respectively. The measured effect is explained in terms of free axial sites in the square-planar arrangement around the copper ion.
mesh_terms: D003300:Copper; D005609:Free Radicals; D005978:Glutathione / Q000031:analogs & derivatives*; D019803:Glutathione Disulfide; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008954:Models, Biological; D011199:Potentiometry; D013482:Superoxide Dismutase / Q000378:metabolism*; D013481:Superoxides
chemical_list: D005609:Free Radicals; D013481:Superoxides; D003300:Copper; D013482:Superoxide Dismutase; D005978:Glutathione; D019803:Glutathione Disulfide