Characterization of a Thermostable Manganese Superoxide Dismutase from a Deep-sea Thermophilic Bacterium
Article
Figures
Metrics
Preview PDF
Reference
Related
Cited by
Materials
Abstract:
An SOD gene (SODBa3) was cloned from the genome of Bacillus sp. SCSIO 15121 that was originally isolated from the sediment of the South China Sea. SODBa3 contains 609 base pairs (bp) and corresponds to 202 amino acid residues. The pET28a (+)-SODBa3 expression vector was constructed in this study, and heterologous expression of soluble SODBa3 was achieved in Escherichia coli BL21 (DE3). Enzymatic properties of the recombinant SODBa3 were then studied; the optimal pH and reaction temperature were 8.0~8.5 and 60 ℃, respectively, and the specific activity of SODBa3 was 3215.6 U/mg. The results showed that the activity of SODBa3 was sensitive to CH3Cl-C2H5OH but was not affected by hydrogen peroxide, indicating that SODBa3 is a Mn2+-dependent enzyme. The thermostability of SODBa3 was also studied by circular dichroism spectroscopy and by examination of changes in the activity of SODBa3 at various temperatures. The results revealed that SODBa3 was relatively stable during treatment at 40~70 ℃ for one hour, and the residual activity was 50% after incubation at 100 ℃ for one hour. The metal ion tolerance experiment indicated that 5 mM Mn2+ had stimulating effects on SODBa3 activity; SODBa3 showed good tolerance to 10% ethanol and dimethyl sulfoxide (DMSO), and the residual activities were 112.56%±9.77% and 98.55%±6.47% of the control activity, respectively. These findings indicate that microbial SODBa3 has high potential for utilization in the industry.
