Purification and properties of Oryza sativa Cu-Zn superoxide dismutase

Superoxide dismutase has been purified to homogeneity from Oryza sativa germinated seeds growth in the dark. The purified enzyme contained two electrophoretically distinct bands on continuous gel electrophoresis or analytical gel electrofocusing. SDS-PAGE showed a single band of an M(r) 15000 while gel chromatography on Sephadex G 100 showed a single peak of an M(r) 32000. It contained two Cu and two Zn ions. The spectra of ultraviolet and visible regions were similar to those of Cu-Zn mammalian and plant superoxide dismutases. The activation energy was estimated at 16 Kcal mol-1.