An electrochemical method for quantification of the radical scavenging activity of SOD

An electrochemical technique for the determination of enzymatic superoxide scavenging activity is described. In amperometric mode of sensor operation the oxidation current was altered by additions of superoxide dismutase (SOD). The 50% inhibition value (150) corresponded to 0.165 U of the standard photometric test of McCord and Fridovich. Influence by inert proteins was much less than in the standard method: The SOD/BSA ratio was 4 x 10(5). Potentially interfering substances, e.g. ascorbic acid and glutathione, were tested. Plasma samples of rats which were treated with modified SOD during cerebral ischaemia, were assayed with the new method and the standard photometric test. A good correlation was found for the analysis in these physiological samples (r = 0.97).