卡介苗HSP70的表达、纯化及活性检测

Expression,purification and activity analysis of BCG HSP70

目的:在大肠杆菌中表达并纯化出具有良好生物学活性的卡介苗HSP70(BCG HSP70)蛋白。方法:利用PCR技术扩增出BCG HSP70的编码基因,将其克隆到pMD18-T载体,测序分析。再将该目的基因亚克隆至pET28a表达载体,转化入大肠杆菌BL21(DE3),获得正确的阳性克隆子后,用IPTG诱导表达。纯化表达产物,SDS-PAGE及Western blot鉴定目的蛋白,并通过脾增生实验检测其生物学活性。结果:扩增的BCG HSP70基因经序列测定与GenBank公布的序列完全一致。表达产物经SDS-PAGE分析,在相对分子质量(Mr)约70000处有表达条带。Western blot结果证实纯化产物在Mr约70000处可见特异性条带。蛋白纯度约96.5%。脾细胞增生试验显示,该蛋白能够明显刺激鼠脾细胞增殖。结论:成功表达并纯化了具有良好生物学活性的BCG HSP70,为进一步研究BCG HSP70及BCG的功能奠定了基础。

AIM： To get BCG HSP70 protein with excellent biologic activity through E. coil expression and purification. METHODS： BCG HSP70 gene was amplified by PCR and inserted into vector pMD18-T. After confirmed by sequencing, the gene was subcloned into expression vector pET28a. Recombinant pET28a/HSP70 was transformed into E. coll. BL21 （DE3）. Recombinant BCG HSP70 protein was expressed with IPTG induction and the purified protein was then identified by SDS-PAGE and Western blot. And its effect on the proliferation of mouse splenocytes was observed. RESULTS： Gene encoding BCG HSP70 which was identical with that published in GenBank was successfully obtained by PCR. SDS-PAGE analysis showed a protein with relative molecular mass of 70 000 was expressed. When the purified protein was detected by Western blot a- nalysis, a specific protein with a molecular mass of 70 000 could be visualized. The purity of the purified protein was about 96.5%. The purified protein could stimulate the proliferation of mouse splenocytes significantly. CONCLUSION： BCG HSP70 is expressed and purified successfully, which would lay a foundation for further research on BCG HSP70 and BCG.