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Superoxide dismutase (SOD) was purified to homogeneity from fruiting bodies of edible mushroom, Lentinus edodes, by ammonium sulfate precipitation, diethylaminoethyl (DEAE)-Sepharose FF ion-exchange chromatography, Sephacryl S-200gel filtration chromatography, and preparative PAGE. The molecular weight of the purified enzyme was estimated to be approximately 54kDa by gel filtration chromatography, and the enzyme was shown to be consisted of two identical subunits of molecular weight 27kDa by SDS-PAGE. The isoelectric point of the enzyme was 4.9 as determined by isoelectric focusing. The enzyme had optimal pH and temperature of pH 8.0 and 20℃, respectively. The activity of the enzyme was inhibited by hydrogen peroxide, but inhibited less by cyanide and azide. The native enzyme was found to contain 0.89g-atom of iron, 0.75g-atom of zinc, and 0.46g-atom of copper per ㏖ of enzyme. Analysis of amino acids composition revealed that the SOD from L. edodes contained a relatively large amount of glutamic acid/glutamine, proline, cysteine, isoleucine, and leucine, but only a small amount of aspartic acid/asparagine, tyrosine, and tryptophan when compared to the other iron-containing SODs.
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