单链抗体与力达霉素辅基蛋白融合蛋白制备过程的优化

Optimization of the preparation process for fusion protein Fv-LDP that composes lidamycin apoprotein and single-chain Fv antibody directed against type Ⅳ collagenase

优化以包涵体形式表达的抗Ⅳ型胶原酶单链抗体与力达霉素辅基蛋白融合蛋白Fv-LDP制备过程。通过单因素或正交设计优化其包涵体制备与溶解、固定化金属螯合层析和分步透析复性过程,Sephadex G-75层析精细纯化蛋白,基于流式细胞术的饱和结合实验检测其抗原结合活性。优化后,Fv-LDP包涵体纯度为63.9%,溶解度为95.7%;纯化后Fv-LDP纯度达95%以上,复性后单体含量占60%,精细纯化后提升为85%,比初始复性条件提高5.6倍,能够与人肺腺癌PAa细胞和肝癌BEL-7402细胞结合。Fv-LDP制备过程被成功优化,为其生产和研发奠定了实验基础,也为其他以包涵体形式表达的基于单链抗体的小型化抗体药物制备提供了比较实用的方法。

This study is to optimize the preparation process of fusion protein Fv-LDP which was expressed in the form of inclusion body and consisted of lidamycin apoprotein LDP and single-chain Fv antibody （scFv） directed against type Ⅳ collagenase. The preparation and the dissolution of inclusion body, the immobilized metal affinity chromatography of the target protein and the renaturization by stepwise dialysis were optimized by single-factor analysis or orthogonal design. In addition, the refolded fusion protein Fv-LDP was refined by Sephadex G-75 chromatography followed by fluorescence-activated cell sorter （FACS）-based saturation binding assay to measure its antigen-binding activity. After optimization of the process, the purity of fusion protein Fv-LDP existed in the inclusion body was 63.9% and the corresponding solubility was 95.7%; Under denaturing conditions, the purity of fusion protein Fv-LDP was more than 95% after the purification process. The percentage of monomeric fusion protein Fv-LDP was 60% after the refolding process, while it was further refined to 85% which was 5.6-fold higher than that of the initial refolding condition. The refined fusion protein Fv-LDP could bind to human lung adenocarcinoma PAa cells and human hepatoma BEL-7402 cells with the dissociation constants （Kd） of 0.176 μmol·L-1 and 0.904 μmol·L-1, respectively. The preparation process of fusion protein Fv-LDP has been successfully optimized, which provides the experimental basis for the production and future development of fusion protein Fv-LDP, and might serve as a relatively practical system for the preparation of other scFv-based proteins expressed in the form of inclusion body.