Purification and characterization of recombinant human superoxide dismutase integrated with resilin-like polypeptide

Human superoxide dismutase (hSOD1) plays an important role in the aerobic metabolism and free radical eliminating process in the body. However, the production of existing SOD faces problems such as complex purification methods, high costs, and poor product stability. This experiment achieved low-cost, rapid, and simple purification of hSOD1 through ammonium sulfate precipitation method and heat resistance of recombinant protein. We constructed a recombinant protein hSOD1-LR containing a resilin-like polypeptide tag and expressed it. The interest protein was purified by ammonium sulfate precipitation method, and the results showed that the purification effect of 1.5 M (NH₄)₂SO₄ was the best, with an enzyme activity recovery rate of 80 % after purification. Then, based on its thermal stability, further purification of the interest protein at 60 °C revealed a purification fold of up to 24 folds, and the purification effect was similar to that of hSOD1-6xHis purified by nickel column affinity chromatography. The stability of hSOD1-LR showed that the recombinant protein hSOD1-LR has better stability than hSOD-6xHis. hSOD1-LR can maintain 76.57 % activity even after 150 min of reaction at 70 °C. At same time, hSOD1-LR had activity close to 80 % at pH < 5, indicating good acid resistance. In addition, after 28 days of storage at 4 °C and 40 °C, hSOD1-LR retained 92 % and 87 % activity, respectively. Therefore, the method of purifying hSOD1-LR through salt precipitation may have positive implications for the study of SOD purification.