Superoxide dismutase: a direct, continuous linear assay using the oxygen electrode.

A continuous method for the assay of superoxide dismutase activity which gives a linear recording of the reaction whose slope is a linear function of the amount of enzyme added is described. An oxygen electrode is used to measure the consumption of oxygen which results from the photochemical generation of superoxide from dissolved oxygen followed by its dismutation to oxygen and hydrogen peroxide. Excess superoxide is scavenged by a tetrazolium salt which oxidizes it back to oxygen.