Production of reactive oxygen-derived species by redox reactions between Fe(II)cytochrome c and oxygen. A kinetic study.
In aerated water solutions Fe(II)Cytochrome c is slowly oxidized to Fe(III)Cytochrome c by molecular oxygen, from which superoxide anion radicals are produced (kobs = 2.7 x 10(-4) min-1 at 37 degrees C and pH = 7.3). The biological importance of this reaction has been evidenced by kinetic investigations in the presence of scavengers. In the presence of Superoxide dismutase the oxidation rate is strongly enhanced (kobs = 3 x 10(-3) min-1 at 37 degrees C). Catalase and mannitol reduce the rate constant values by 50% and 25% respectively either in the presence or in the absence of Superoxide dismutase: differences between rate constants correspond to the differences in stoichiometric redox ratios indicating that hydrogen peroxide and hydroxyl radicals are formed subsequently to the production of superoxide anion radicals.
Ferri
A
A
Department of Biochemistry and Molecular Biology, University of Ferrara, Italy.
Calza
R
R
D000818:Animals; D002374:Catalase / Q000737:chemistry; D003574:Cytochrome c Group / Q000737:chemistry*; D006861:Hydrogen Peroxide / Q000138:chemical synthesis; D017665:Hydroxyl Radical / Q000138:chemical synthesis; D007700:Kinetics; D008353:Mannitol / Q000737:chemistry; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D017382:Reactive Oxygen Species / Q000138:chemical synthesis*; D013482:Superoxide Dismutase / Q000737:chemistry; D013481:Superoxides / Q000138:chemical synthesis*
D003574:Cytochrome c Group; D017382:Reactive Oxygen Species; D013481:Superoxides; D017665:Hydroxyl Radical; D008353:Mannitol; D006861:Hydrogen Peroxide; D002374:Catalase; D013482:Superoxide Dismutase; D010100:Oxygen