Aging of the erythrocyte--XVII. Changes in the properties of superoxide dismutase.

1. An increase in the sensitivity of superoxide dismutase (SOD) to the action of diethyldithio-carbamate and cyanide was observed in red cell fractions of greater age. 2. It suggests that SOD inactivation during erythrocyte aging is not an "all or none" process but involves transition(s) between enzyme forms of different properties. 3. An increase in the ratio of less mobile to the more mobile SOD bands was observed by polyacrylamide-gel-electrophoresis in older erythrocytes.