Expression and purification of human surfactant protein A1 in E. Coli

Objective To study the expression and purification of surfactant protein A1(SP A1) and preliminary analysis of its antigenicity.Methods SP A1 gene was cloned into prokaryotic vector pGEX 2T, transformed in E. coli JM101, JM105, JM109, XL1 blue and BL21 (DE3) and expressed at various temperature. The fusion products of SP A1 protein was purified according to the purification procedures of inclusion bodies and the glutathione sepharose 4B affinity chromatography. The antigenicity of SP A1 was analyzed by ELISA and Western blot. The fusion protein was digested by thrombin.Results The gene was highly expressed in all the five hosts, the complete and incomplete products accounted for about 6 7% to 14 8% of the total bacterial protein. Only BL21(DE3) expressed complete SP A1 proteins at 28℃ and SP A1 was 10% of the total bacterial proteins. The purity of the purified protein was about 95%. SP A1 was obtained by digesting with the thrombin, and the molecular weight of SP A1 was 26 000. SP A1 protein was recognized specifically by the anti SP A polyclonal antibodies.Conclusion The human tissue specific SP A1 protein was highly expressed in prokaryotic E. coli system and showed a satisfied antigenicity.