Cloning, purification and enzymatic characterization of recombinant human superoxide dismutase 1 (hSOD1) expressed in Escherichia coli

Superoxide dismutase 1 (SOD1) is a metalloenzyme that catalyzes the disproportionation of superoxide into molecular oxygen and hydrogen peroxide. In this study, the human SOD1 (hSOD1) gene was cloned, expressed and purified. The hSOD1 gene was amplified from a pool of Bxpc3 cell cDNAs by PCR and cloned into expression vector pET-28a (+). The recombinant soluble hSOD1 was expressed in E. coli BL21 (DE3) at 37°C and purified using nickel column affinity chromatography. Soluble hSOD1 was produced with a yield of 5.9 μg/mL medium. As metal ions can have a certain influence on protein structure and activity, we researched the influences of different concentrations of Cu2+ and Zn2+ on hSOD1 activity at induction and the time of activity detection. The results implied that Cu2+ and Zn2+ do not enhance SOD1 expression and solubility; they can, however, improve the catalytic activity at induction. Meanwhile, Cu2+ and Zn2+ also enhanced the enzyme activity at the time of detection. Furthermore, most other bivalent cations had the potential to replace Zn2+ and Cu2+, and also improved enzyme activity at the time of detection.