Measurement of Serum Superoxide Dismutase Activity by Electron Spin Resonance

Abstract

We measured serum superoxide dismutase activity by electron spin resonance, using 100mM 5, 5-dimethyl-1-pyrroline-N-oxide (DMPO) as a trap. The addition of superoxide dismutase decreased the height of the DMPO-OOH signal produced by the hypoxanthine-xanthine oxidase system. Serum superoxide dismutase activity was determined from a quantitative line for superoxide dismutase. When bovine Cu, Zn-superoxide dismutase (50, 000U/kg) was injected intravenously into rats, the superoxide dismutase activity decreased almost linearly with a half life of about 6min. This method allowed direct detection of superoxide radicals and new measurement of superoxide dismutase activity.