Objective: To express and purify the Toxoplasma gondii RH strain immune mapped protein 1 (IMP1) protein through the prokaryotic expression system, and to identify the purified protein. Method: Gene of TgIMP1 was attained by RT-PCR and the amplified product was identified by TA-clone and sequencing. The identified fragment of IMP1 was connected into the expression vector pET28b and the recombinant pET28b-TgIMP1 was identified by double digestion and sequencing. The fusion protein TgIMP1 with 6 ×

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... His tag was expressed in E. coli BL21 (DE3) host and the optimal inducing conditions were investigated by adjusting the harvesting time interval, inducing temperature and concentration of isopropyl β-D-thiogalactoside (IPTG). The solubility detection of TgIMP1 protein and the massive purification of it were conducted with Ni 2+-affinity purification. The purified product was identified by Coomassie-stained SDS-PAGE and immune-blotting. Results: The prokaryotic expression recombinant pET28b-TgIMP1 was successfully established on the basis of the identified TgIMP1 gene by TA-clone. Recombinant proteins of TgIMP1 could be efficaciously and largely expressed in E. coli BL21 strain with 0.3 mM IPTG for 9 h at 20°C, and with the characteristics of good stability, high solubility and purity, and fine immunity. Conclusion: TgIMP1 protein could be expressed in the prokaryotic host strain with satisfied stability and solubility. Our findings may lay the foundation for the future protein-based investigations such as development of subunit vaccine and structural determination.