Abstract: Iron-superoxide dismutase was found in the crude extract from leaves of Spinacea oleracea after gradient PAGE analysis.The enzyme was isolated and purified to homogeneity by using ammonium sulfate fractionation followed by DEAE-Cellulose-A₅₂ chromatography and Sephadex G-100 gel filtration.The molecular mass of the purified Fe-SOD is about 42.6 kD,and its subunit molecular mass is about 21 kD.Metal analysis reveals that the protein contains about 2.6 gram atoms of iron per molecule.The purified enzyme exhibits one absorption maximum in the ultraviolet at 278 nm with a low shoulder of absorption at 260 nm and 290 nm.Its isoelectric point is 4.6.In the aspects of amino acid composition,the enzyme from spinach is most similar to Fe-SOD from other sources.