人源VEGF单克隆抗体Fabμ和Fc5μ片段的制备

Preparation of Fabμ and Fc5μ Fragments from Human Anti-VEGF Monoclonal Antibodies

用胰蛋白酶将Mr为900 k的人源VEGFIgM单抗切成Fabμ和五聚的Fc片段(Fc5μ)。用Sephacryl S-200对分离纯化两片段,用间接ELISA法测定IgM抗体及Fabμ片段的抗原结合活性。结果表明:按酶∶IgM为1∶30加入胰蛋白酶,63℃酶切30 min,可使IgM水解完全。用Sephacryl S-200纯化后,片段纯度≥90%。经ELISA间接法测定Fabμ的抗原结合活性后发现,虽与完整的五聚体IgM相比亲和力有所下降,但仍有较好的抗原结合活性,相对亲和力为4.29×108。

Fabμ and Fc5μ were prepared from human VEGF monoclonal antibody digestion with trypsin in the suitable buffer system. Exploring the appropriate digestion time, so as to achieve optimal yield and purity. Then purifying the fragments with Sephacryl S-200 and identiying the antigen binding activity of purified IgM and Fabtx by indirect ELISA. The results showed that the IgM was completely arid efficiently digested at a trypsin-to-IgM ratio of 1 ： 30 in 0. 1 mol/L Tris-HCl, 0. 2 mol/L NaCl, 0. 01 mol/ L CaCl2, （pHS. 3） at 63℃ for 30min. The purity of fragments achieved more than 90%. Finally, the re sult of the affinity constant measured by indirect ELISA was 4. 29×10^8. It suggested that the Fabμ still had better antigen binding activity although it declined as compared with the intact IgM.