融合蛋白ABD-Fc-IL-2的真核表达及其生物学活性鉴定

Eukaryotic expression and biological activity identification of fusion protein ABD-Fc-IL-2

目的 真核表达融合蛋白ABD-Fc-IL-2,并检测其生物学活性。方法 通过直接PCR及重叠延伸PCR法扩增目的基因SP-ABD-Fc-IL-2,连接至载体pcDNA3.1(+),获得重组质粒pcDNA3.1/SP-ABD-Fc-IL-2。将重组质粒转染CHO-S细胞表达融合蛋白ABD-Fc-IL-2,并进行Protein A beads亲和层析纯化。Western blot法检测纯化融合蛋白的特异性,CTLL-2/MTT细胞增殖比色法测定其生物学活性,pull down/Western blot法检测融合蛋白中链球菌蛋白G的白蛋白结合结构域(albumin-binding domain,ABD)与人血清白蛋白(human serum albumin,HSA)的相互作用。结果重组质粒pcDNA3.1/SP-ABD-Fc-IL-2经双酶切及测序鉴定,证明构建正确。纯化融合蛋白ABD-Fc-IL-2纯度达90%,可与鼠抗IL-2单克隆抗体发生特异性结合,生物学活性为3.29×108IU/mL,融合蛋白中ABD与HSA可相互结合。结论 真核表达的融合蛋白ABD-Fc-IL-2具有较高的生物学活性,可促进CTLL-2细胞增殖,且保持了ABD片段与HSA结合的能力。

Objective To express the fusion protein ABD-Fc-IL-2 in eukaryotic cells and detect its biological activity.Methods The target gene SP-ABD-Fc-IL-2 was amplified by direct and overlapping PCR,and then ligated to vector pcDNA3.1(+).The obtained recombinant plasmid pcDNA3.1/SP-ABD-Fc-IL-2 was transiently transfected into CHO-S cells to express the fusion protein ABD-Fc-IL-2,which was purified by Protein A beads affinity chromatography.The specificity of the purified fusion protein was detected by Western blot,the biological activity was detected by CTLL-2/MTT cell proliferation colourimetry,and the interaction between ABD fragment and human serum albumin(HSA)was detected by pull down/Western blot.Results The recombinant plasmid pcDNA3.1/SP-ABD-Fc-IL-2 was constructed correctly as identified by restriction analysis and sequencing.The purified fusion protein ABD-Fc-IL-2 showed a purity of 90% and bound specifically to mouse anti-IL-2 monoclonal antibody with the biological activity of 3.29 × 108IU/mL.The ABD of fusion protein and HSA bound to each other.Conclusion The eukaryotic fusion protein ABD-Fc-IL-2 had high biological activity,which promoted the proliferation of CTLL-2 cells and maintained the binding ability of ABD fragment to HSA.