BAC5-scFv的表达、复性及活性检测

目的探讨以包涵体形式表达的抗鼻咽癌单克隆抗体(mAb)BAC5的单链抗体(BAC5-scFv)的纯化、复性方法,并对其活性进行检测。方法扩增pET-22b-scFv质粒转化的大肠杆菌BL21(DE3)菌株,培养、破菌后,分离和变性包涵体,用Ni-NTA His Bind层析柱纯化变性的scFv。经稀释、透析及尿素梯度凝胶层析柱3种方法进行复性。用细胞免疫组化染色和蛋白印迹法(Western blot),鉴定复性后的BAC5-scFv的免疫活性。结果Ni-NTA His Bind亲和层析柱能有效纯化变性的scFv。以尿素梯度凝胶层析柱复性的蛋白回收率最高。免疫细胞化学染色法检测及Western blot分析证实,复性后的BAC5-scFv可与CNE2细胞上的抗原特异性结合。结论以包涵体形式表达的BAC5-scFv经变性、纯化及复性后,获得良好的免疫活性,为大量制备具有活性的BAC5-scFv,并用于鼻咽癌的放射免疫显像和治疗研究奠定了基础。

Expression, renaturation and activity of BAC5-scFv expressed as inclusion body in E.coli

AIM: To study the renaturation, purification and binding activity of scFv of anti-nasopharyngeal carcinoma monoclonal antibody(mAb) BAC_5 expressed as inclusion body in E.coli. METHODS: The E.coli BL21(DE3) transformed with the pET 22b-scFv was cultured and pulvereged by ultrasonic cell disintegrator. The collected inclusion bodies were denatured with 8 mol/L urea and renatured by dilution refolding, step dialysis and gel filtration chromatography. Binding activity of renatured BAC_5-scFv was determined by immunohistochemical staining and Western blot. RESULTS: BAC_5-scFv purified though Ni-NTA His Bind chromatographic clomn showed high purity. The highest proteins recovery rate was obtained through gel filtration chromatography. It was proved by Western blot and immunocytochemical staining that the renatured BAC_5-scFv protein could specifically bind to CNE2 cells. CONCLUSION: BAC_5-scFv expressed as inclusion body retained good activity after being dissolved, purified and renatured, which paves the way for preparing large amount of BAC_5-scFv to be used for the study of radioimmunoimaging and therapy of nasopharyngeal carcinoma.