Expression of human plasminogen kringle 5 as fusion protein with truncated hIFNgamma gene in Escherichia coli

The human interferon gamma (hIFNgamma) gene was used as a fusion partner to mediate the expression of heterologous proteins and the effect of the fusion partner length on the expression of the heterologous protein was researched. Plasminogen kringle 5 (pk5), an inhibitor of angiogenesis, was fused to hIFNgamma and its serially truncated fragments, respectively, and the expression of fusion proteins was determined by SDS-Page gel. The pk5 protein was obtained readily by the introduction of sequences recognized by protease factor Xa at the fusion site and ion-exchange chromatography was employed to purify pk5. The recovery of the biological activities of pk5 was studied using the orthogonal experimental design L9 (3(4)) (four factors, three levels, nine experiments) and evaluated by measurement of anti-endothelial cell proliferation in vitro.