hEGF和hbFGF的C端(78-154aa)融合蛋白的表达、纯化及活性测定

目的:将人表皮生长因子(hEGF)与人碱性成纤维细胞生长因子(hbFGF)的C端连接,构建出既可与肝素结合,又具有促进细胞生长活性的融合蛋白,并在大肠杆菌中高效表达。方法:将PCR扩增hEGF全基因与PCR扩增hbFGF5端的231bp的片段连接,克隆到表达载体pJN,构建出含融合基因的表达质粒pJRH。将pJRH转化BL21(DE3)表达菌株,获得融合蛋白的表达菌株pJRH(BL)。Westernblot检测表达产物免疫学活性。表达产物上肝素亲和柱和分子筛进行纯化。结果:融合蛋白表达产量为30%,融合蛋白不仅能与肝素结合,而且具有促细胞增殖的活性。Westernblot检测结果显示融合蛋白有EGF的免疫活性。融合蛋白的等电点为5.2。结论:本研究构建了一个hEGF和hbFGF的C端的融合蛋白,该蛋白基本保持了两者原有的生物活性。作为一个新的活性因子,本研究为探讨活性因子蛋白结构与功能的关系奠定基础。

Expression, purification and biological assay of recombinant hEGF-hbFGF(78-154aa)fusion protein

AIM: To construct a recombinant hEGF-hbFGF(78-154aa)fusion protein, which not only has the heparin-binding ability, but also promotes the growth of the cells, and to express the fusion protein in E. coli expression system with high expression level.METHODS: hEGF gene was joined with 231 bp fragment coding hbFGF(78-154aa) and expressed in E. coli. The fusion protein was purified using affinity chromatography of heparin-Hyper D and analyzed with western blot. The pI value and the biological activity were both assayed.RESULTS: The fusion protein was expressed in a high expression level of about 30% of the total cell protein, as estimated by SDS-PAGE. Western analysis results showed that the antigenicity of fusion protein was similar to hEGF. Fusion protein could not only bind heparin but also promote the growth of 3T3 cell. The pI value of fusion protein was 5.2.CONCLUSION: The recombinant hEGF-hbFGF(78-154aa) fusion protein possessed the characteristics of both hEGF and hbFGF. This new-designed protein would become a good object for the research on the relationship between the structure and the function of the growth factor.