Construction of three different recombinant scorpion fusion proteins with bifunctional activity.

This is the first report of three different fusion proteins with an antitumor-analgesic peptide obtained from Chinese scorpion Buthus martensii Karsch (BmKAGAP). The fusion proteins were constructed in the form of chimeric toxins, aiming to obtain bifunctional analgesic and antitumor activity. The fusion proteins consisted of luteinizing hormone-releasing hormone (LHRH), three different types of flexible linkers (L1, Ser-Ser-His-His-His-His-His-His-Ser-Ser-Gly-Leu-Val-Pro-Arg-Gly-Ser-His-Met; L2, Gly-Gly-Gly-Ser-Gly-Gly-Gly-Ser; L3, Ser-Gly-Gly-Ser-Gly-Gly-Ser-Gly-Gly-Gly-Ser-Ser-Gly-Gly-Ser-Gly-Gly-Gly-Gly-Ser-Gly-Gly-Gly-Gly-Ser), and BmKAGAP. The genes coding three fusion proteins were cloned and expressed in E. coli in soluble form. Following two successive column chromatographic separations, purified fusion proteins were obtained. These fusion proteins exhibited analgesic activity in mice and were cytotoxic to a hepatocellular carcinoma cell line Hep3B.