盐穗木金属硫蛋白HcMT的体外自由基清除活性及抗氧化能力*

目的: 原核表达盐穗木(Halostachys caspica C. A. Mey.)金属硫蛋白HcMT并探究其抗氧化活性。方法: 构建原核表达载体pET-32a-HcMT,转化至大肠杆菌Escherichia coli BL21,加入Zn²⁺胁迫培养(终浓度为200 μmol/L),分离纯化得到Zn-HcMT,测定Zn-HcMT自由基清除活性和总抗氧化能力,制备复合物Zn-HcMT/TiO₂并做FTIR表征。结果: 通过原核表达获得融合蛋白Zn-HcMT,对·OH、O₂·^-、DPPH自由基具有较强的清除活性,对·OH、O₂·^-的IC₅₀分别为0.386 mg/mL、0.038 mg/mL。融合蛋白浓度为0.01 mg/mL时,对DPPH清除率达(37.43 ± 0.006 8)%,浓度为0.3mg/mL时TEAC(trolox-equivalent antioxidant capacity)值为(1.023 ± 0.01)mmol/L,融合蛋白还原力A₇₀₀为0.142 ± 0.055,FTIR图谱同时表现了Zn-HcMT和TiO₂吸收特性。结论: Zn-HcMT具有良好的清除ROS活性及较强的抗氧化能力,在化妆品领域有潜在应用前景。

Free Radical Scavenging Activity and Antioxidant Capacity of Metallothionein HcMT from Halostachys caspica in vitro

Objective: To express metallothionein HcMT of Halostachys caspica in prokaryotic cells and explore its antioxidant activity, so as to lay a foundation for its application in the field of cosmetics. Methods: the prokaryotic expression vector pET-32a-HcMT was constructed, transformed into Escherichia coli BL21, cultured under Zn²⁺ stress (the final concentration was 200 μmol/L), separated and purified to obtain Zn-HcMT, and its free radical scavenging activity and total antioxidant capacity were measured. The complex Zn-HcMT/TiO₂ was prepared and characterized by FTIR. Results: The fusion protein Zn-HcMT was obtained by prokaryotic expression. It had strong scavenging activity for ·OH,O₂·^- and DPPH free radicals. The IC₅₀ of ·OH and O₂·^-were 0.386 mg/mL, 0.038 mg/mL, respectively. The DPPH clearance rate of 0.01 mg/mL fusion protein was (37.43 ± 0.006 8)%, the TEAC value of 0.3mg/mL fusion protein was (1.023 ± 0.01)mmol/L, and the reducing power of 0.3 mg/mL fusion protein A₇₀₀ was 0.142 ± 0.055. FTIR spectra showed the absorption characteristics of Zn-HcMT and TiO₂ at the same time. Conclusion: Zn-HcMT has a good ROS scavenging activity and strong antioxidant capacity. It has great application potential in the field of cosmetics.