重组融合蛋白抗CD20Fab-LDM的构建、表达及体外活性研究

Construction,expression and in vitro specific killing activity of a recombinant fusion protein:anti-CD20Fab-LDM

目的构建和表达抗CD20Fab-LDP(力达霉素辅基蛋白)融合蛋白,制备强化融合蛋白抗CD20Fab-LDM(力达霉素),并测定该融合蛋白的生物学活性。方法采用PCR和overlapPCR方法构建抗CD20Fab-LDP融合蛋白,并用双脱氧终止法测定DNA序列;采用亲和层析法纯化该产物,并用Western blot鉴定纯化产物;采用FACS方法鉴定纯化产物与靶细胞的结合活性;采用冷乙二醇法制备强化融合蛋白抗CD20Fab-LDM;采用MTT法鉴定抗CD20Fab-LDM对CD20+Raji细胞特异性的细胞毒作用。结果DNA序列测定结果表明抗CD20Fab-LDP融合蛋白已构建成功,可溶性表达产物的产量可达4mg.L-1以上,具有与Raji细胞(CD20+)结合的活性,与抗CD20Fab的亲合常数相当,抗CD20Fab-LDM体外能特异性杀伤Raji细胞,IC50值为0.9×10-10mol.L-1。结论成功地构建了抗CD20Fab-LDP融合蛋白,并获得可溶性高效表达,表达产物具有与相应靶抗原结合的活性,并成功制备了抗CD20Fab-LDM强化融合蛋白,体外能特异性杀伤CD20+的Raji细胞。

Aim To construct and express anti-CD20Fab-LDP,generate anti-CD20Fab-LDM and identify its biological activity.Methods PCR and overlapping PCR were used to construct anti-CD20Fab-LDP.DNA sequence was analyzed by the Terminus of Dideoxy Nucleotide.The product was purified by affinity chromatography and analyzed by Western blot and its antigen-binding activity was examined by FACS.Specific killing activity in vitro of anti-CD20Fab-LDM was analyzed by MTT.Results The data of DNA sequence showed that anti-CD20Fab-LDP was correct.The fusion protein was recovered in high yield（up to 4 mg·L^-1）after proteinG purification.The fusion protein could bind to Raji cells（CD20^＋）,and similar affinity data were obtained with anti-CD20Fab.Anti-CD20Fab-LDP showed potent cytotoxicity to Raji cells with IC50 values of 0.9×10^-10 mol·L^-1.Conclusions Anti-CD20Fab-LDP with high level expression was successfully obtained and could bind to Raji cells cells.Anti-CD20Fab-LDM showed specific killing activity to Raji cells in vitro.