High Expression of a cDNA Coding for Human Lymphotoxin alpha Derivative in E. coli and Purification of Its Protein Product.

Using PCR, a cDNA coding for human lymphotoxin α derivative (hLTαDa) lacking 27 amino acids at Nterminal of natural hLT was constructed. The expression construct was expressed in E.coli BL21(DE3). The product of expression was in the form of inclusion bodies, and accounted for 60%-80% of total bacterial proteins . The product protein was purified to over 95% by treatments of inclusion bodies. The specific activity of hLTαDa was above 2×108 IU(per mg protein). Its cytotoxic activity can be neutralized by monoclone antibody against hLT. The antitumor effects of hLTαDa were also tested in vitro and in vivo.