Abstract: The soluble expression of the fusion protein rES-CSP was accomplished by condition optimization in order to obtain amount of active protein conveniently. Its biological activity was detected after purification. The fusion protein was made possible as a pharmaceutical. The rES-CSP was expressed under normal conditions, and the optimal strain was selected by SDS-PAGE. After optimization of induction time and temperature, the targeted protein was analyzed by Western Blot, purified by Ni-NTA, and the purity of the fusion protein was analyzed by RP-HPLC. The biological activity of fusion protein was detected by CCK-8 and flow cytometry. Results showed that the monoclonal strain with the target protein of about 43.84% of the total bacterial protein was selected as the research object. Soluble fusion protein rES-CSP was expressed at 25 ℃ for 20 h, and the amount was higher. The purity of rES-CSP after purification was over 98%. Biological assay showed that rES-CSP inhibited the proliferation of hepatoma cell line HepG2 and had stronger binding ability to HepG2.

Key words: soluble expression, CSP I-plus modified human endostatin rES-CSP, biological activity identification