Wang Quanfu, Nie Ping, Hou Yanhua, Wang Yatong
School of Marine Science and Technology, Harbin Institute of Technology, Weihai, 264209, PR China.
School of Marine Science and Technology, Harbin Institute of Technology, Weihai, 264209, PR China.
Protein Expr Purif. 2020 Sep;173:105661. doi: 10.1016/j.pep.2020.105661. Epub 2020 May 5.
A novel superoxide dismutase (referred hereafter to as HsSOD) from the psychrophilic bacterium Halomonas sp. ANT108 was purified and characterized. Escherichia coli (E. coli) was selected as the expression host. After recombinant HsSOD (rHsSOD) was purified, the specific activity was determined to be 213.47 U/mg with a purification ratio of approximately 3.61-fold. SDS-PAGE results demonstrated that rHsSOD has the molecular weight of 31.3 kDa, and type identification revealed that it belongs to Cu/Zn SOD. The optimum activity of rHsSOD was at 35 °C and 28% of its maximum activity remained at 0 °C. Further enzymatic assays indicated that rHsSOD exhibited thermal instability with a half-life of 20 min at 60 °C. Moreover, Cu and Zn significantly promoted rHsSOD activity. The values of K and V were 0.33 mM and 476.19 U/mg, respectively. Interestingly, rHsSOD could avoid DNA strand breakage formed by metal-catalyzed oxidation, demonstrating its antioxidant capacity. To summarize, the results suggested that rHsSOD has relatively high catalytic efficiency and oxidation resistance at low temperatures.
从嗜冷细菌嗜盐单胞菌属ANT108中纯化并鉴定了一种新型超氧化物歧化酶（以下简称HsSOD）。选择大肠杆菌作为表达宿主。重组HsSOD（rHsSOD）纯化后，比活性测定为213.47 U/mg，纯化倍数约为3.61倍。SDS-PAGE结果表明，rHsSOD的分子量为31.3 kDa，类型鉴定表明它属于铜/锌超氧化物歧化酶。rHsSOD的最佳活性温度为35°C，在0°C时仍保留其最大活性的28%。进一步的酶活性测定表明，rHsSOD表现出热不稳定性，在60°C下的半衰期为20分钟。此外，铜和锌显著促进rHsSOD的活性。K和V值分别为0.33 mM和476.19 U/mg。有趣的是，rHsSOD可以避免金属催化氧化形成的DNA链断裂，证明了其抗氧化能力。总之，结果表明rHsSOD在低温下具有较高的催化效率和抗氧化性。
