Efficient expression of human plasminogen kringle 1 - 3 domain gene in E. coli

The kringle 1 - 3 domain (K1 - 3) of plasminogen is a potent inhibitor of endothelial cell proliferation and angiogenesis. The gene expression of the K1 - 3 domain of human plasminogen in E. coli is reported. The K1 - 3 gene was first inserted into the expression vetor pET - 17b, resulting in plasmid pET - K13. pET - K13 was then transformed into E. coli BL21 (DE3). The transformant E. coli BL21 (DE3, pET - K13) was used to detect the gene expression. SDS-PAGE result showed that the K1 - 3 gene was efficiently expressed in E. coli BL21 (DE3, pET - K13) by IPTG induction. The expressed product constitutes 24% of the total bacterial protein as estimated by densitometer and exists as inclusion body. Western blot result indicates that the recombinant protein reacts with antiserum against human plasminogen.