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Consideration and comparison of specific superoxide dismutase activities shows that--of the values calculated for the same wet weight--the superoxide dismutase activity of the liver is more than twice that of the other tissues. This indicates the important metabolism-directing role of the liver. The large amount of superoxide dismutase (even the tissular superoxide dismutase alone) protects the tissues from the effects of the O(2)-radical, and the function of the superoxide dismutase probably opposing the cytochrome P-450 may be important as regards the hydroxylase effect.

The radical produced aerobically in the glucose oxidase reaction reduces the oxidated cytochrome c. The extent of reduction depends on the concentrations of substrate (glucose) and enzyme. Superoxide dismutase purified from various sources does not inhibit the cytochrome c reduction, but catalase does, in proportion to its concentration. This inhibition, which might be utilized for quantitative catalase determinations, provides further evidence for the formation of H2O2 in the glucose oxidase reaction.