Abstract
Superoxide dismutase (SOD) was isolated and partially purified from pooled mouse erythrocytes by treating with organic solvents followed by gel filtration and ion-exchange chromatography. The purified SOD showed two major and three minor bands on polyacrylamide gel electrophoresis. All these bands were proven to be cuprozinc SOD (Cu, Zn-SOD) by the KCN inhibition test. The Cu, Zn-SOD was a dimer with a molecular weight of 32, 000 daltons consisting of two subunits, each of which with a molecular weight of 16, 000 daltons. Ultraviolet absorption spectrum and PAS staining patterns of the Cu, Zn-SOD indicated that the enzyme contains very low levels of both tyrosine and tryptophan residues and carbohydrates. Lyophilization of the purified enzyme induced an SOD-active, slow moving extraband on polyacrylamide gel electrophoresis, possibly as a result of aggregation during lyophilization.
