葡萄球菌肠毒素 B 突变体的构建及其抗肿瘤活性分析

目的：通过对葡萄球菌肠毒素B（SEB）32位His进行定点突变，获得抑瘤效果显著增强的SEB突变体。方法：利用基因定点突变的方法，将SEB的32位His替换为Asn，将重组质粒转入大肠杆菌中诱导表达，用CM弱阳离子层析柱纯化获得重组蛋白，用SDS-PAGE和Western印迹对其进行鉴定，并用增殖实验检测其丝裂原活性，通过MTS法检测其体外抗肿瘤活性。结果：构建并高效表达了突变体蛋白SEB（H32N），纯化获得了足够纯度的突变体蛋白；体外实验表明，在相同浓度下，SEB（H32N）的丝裂原活性及体外抗肿瘤活性明显优于野生型SEB。结论：同野生型SEB相比，突变体蛋白SEB（H32N）对肿瘤生长的抑制作用得到了提高。

Construction and Anti-Tumor Activity Analysis of Staphylococcus Enterotoxin B Mutant

Objective： The anti-tumor activity of staphylococcal enterotoxin B（SEB） was enhanced, by substitut- ing His32 of SEB for Ash through site-directed mutagenesis. Methods： A mutant superantigen SEB（H32N） was constructed by site-directed mutagenesis, the protein was expressed in E.coli BL21 after induced, purified by CM ion-exchange chromatography and identified by SDS-PAGE and Western blot. Mitogen biological activity was ana- lyzed by cell proliferation assay in vitro, and the anti-tumor activity was analyzed using MTS method in vitro. Re- sults： The mutated protein SEB（H32N） was expressed in E.coli efficiently and purified. The results showed that at the same concentration, the mitogen biological activity and anti-tumor effect of SEB（H32N） were better than SEB on a variety of tumor cells in vitro. Conclusion： Compared with the wild type SEB, SEB（H32N） mutant ex- hibited an enhanced anti-tumor effect.