In 1969 a previously obscure copper protein of red blood cells, erythrocuprein, was shown to catalyse the dismutation of superoxide radicals. Erythrocuprein thus became superoxide dismutase and the object of intensive study. Superoxide dismutase is typically an enzyme of aerobic organisms which utilize oxygen as the major electron acceptor. The presence of superoxide dismutase in microorganisms has been found to parallel their tolerance for oxygen. We recently described the isolation and properties of two forms of superoxide dismutase from human erythrocytes, SOD I and SOD II (Bannister et al., 1976). These can be obtained from a haemolysate of red blood cells after precipitation of the hemoglobin with a mixture of ethanol and chloroform.

peer-reviewed