Superoxide dismutase decay kinetics, pulse generated

Manganese compounds of biologic importance are examined by pulse radiolysis e.g., the rate of dismutation of radiation-generated Of is catalyzed by Escherichia coli, Mn-containing superoxide dismutase involving electron transfer in which enzymes with Mn(IV), Mn(IIl), Mn(II) and Mn(I) oxidation states are involved. A kinetic model for the reaction mechanism of an Mn dismutase from Bacillus stearothermophilus accounts for the variation of the rate of decay on the concentrations of Oj, enzyme, HjOj, NaNj, KCN and H+. 

Another direct assay method is based on decay kinetics of pulse generated O2 (Takahashi and Asada, 1981). Superoxide was produced within 10 msec by a flash of light through the excitation of flavin mononucleotide in the presence of A,A,A, A -tetramethylethylenedi-amine and oxygen. The kinetics of O2 decay in the presence and absence of enzyme were followed at 240 nm. The catalytic rate constant for bovine erythrocyte copper/zinc superoxide dismutase was found to be 1.75 x... 

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