Electrolytic Univalent Reduction of Oxygen in Aqueous Solution Demonstrated with Superoxide Dismutase

Abstract

The superoxide anion, generated electrolytically at a platinum electrode in buffered aqueous solution, was detected by its ability to cause the oxidation of epinephrine to adrenochrome. The rate of electrolytic oxidation of epinephrine varied with the applied potential in a manner reminiscent of an oxygen reduction half wave. This oxidation of epinephrine was dependent upon the presence of oxygen and was completely inhibitable by superoxide dismutase. It may be concluded that superoxide radicals, generated at the electrode, diffuse into the solution to an extent which allows reaction with small molecules such as epinephrine or with enzymes such as superoxide dismutase.