Purification of Copper-Zinc Superoxide Dismutase from Human Erythrocytes and Partial Characterization

Abstract

ABSTRACTCopper-zinc superoxide dismutase (CuZnSOD; E.C:1.15.1.1) catalyzes the dismutation of the superoxide radical to hydrogen peroxide and oxygen. In this study, CuZnSOD was isolated from human erythrocytes using DEAE-cellulose chromatography and copper chelate affinity chromatography. The enzyme was purified 196.3 fold with 33.8% efficiency. The molecular weight of CuZnSOD was determined as 20 kDa by SDS-PAGE.Vmax and Km values were determined as 5000 U/mg protein and 3.10−3 mM Xanthine, respectively. Maximum CuZnSOD activity was observed at 15°C. Activation energy was calculated as 16.856 kj/mol and initiation of denaturation temperature was calculated as 19°C. Turnover number (kcat) and catalytic efficiency (kcat/Km) were found to be 1667 s−1 and 5.6 x105 s−1.mM−1 Xanthine−1 respectively.The enzyme was found to have good storage stability as 93.6% of initial activity after 28 days of storage in 50% glycerol solution at -20°C.