Speciation and effectiveness in promoting oxyradical damage

Copper in trace amounts can distort the kinetics of superoxide reactions with other compounds, because it effectively catalyses the dismutation reaction [143], Complexation by edta prevents this, as well as the reduction of hydrogen peroxide. Thus, edta protects the bases of DNA against copper-mediated damage [144]. However, edta will not protect if iron is involved, since rates of reaction between this metal complex and oxygen, superoxide or hydrogen peroxide are appreciable. 

The observation that there is poor agreement in the experiments mentioned above - not to mention more complicated studies such as those on lipid peroxidation, see ref. [39] - should be a reason for concern. When designing experiments one could calculate which molecules present in solution will react with superoxide or the hydroxyl radical. The recent combined compilation of rate data on superoxide, hydrated-electron, and hydroxyl- and hydrogen- 

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