Expression Of Scorpion Analgesic Peptide â…£ And Its Analgesic Activity Contrast

Scorpion venom is a kind of rare Chinese traditional medicine which possesses important clinic value. There are some functions such as antitumor, analgesic, anti-eclampsia, anti-epilepsy, blood pressure falling, and anti-forming of thrombus, etc. We pay much attention to researching whether the change of the scorpion venom’s structure affects its activity. This paper has focused on expression and purification of the recombinant analgesic peptideⅣ（SAPⅣ） and its biological activity in mice.According to the sequence of constructed SAPⅣ-C-Tag_His, five different primers were designed. By the method of PCR, three target genes were achieved. One was SAPⅣwith His-Tag in N-terminus named N-Tag_His-SAPⅣ, and the other two were N-Tag_His-SAPⅣ-land N-Tag_His-SAPⅣ-2, which were removed one and two amino acids from C-terminus of N-Tag_His-SAPⅣrespectively. Subsequently, they were cloned into expression vector pNJUTRX-1. Transformed the recombined expression vector into the E. coli BL21 （DE3）, and then induced the expression by adding IPTG. Three different proteins were obtained, which were N-Tag_His-SAPⅣ, N-Tag_His-SAPⅣ-1 and N-Tag_His-SAPⅣ-2. And the recombinant SAPⅣs were all in soluble form. By Chelating Sepharose Fast Flow and SP-Sepharose Fast Flow, purified samples were obtained to do the pharmaceutical tests.The results of mouse writhing test showed that the recombinant SAPⅣhad inhibitive effect on visceraglgia. At a does of 2.71×10^-2μmol/kg body weight, SAPⅣ-C-Tag_His inhibited the 41.06%（p＜0.01） of the twisting action of the mice induced by acetic acid while the inhibition ratio of N-Tag_His-SAPⅣwas 47.98%（p＜0.01）. By SPSS test, it showed the analgesic activities of recombinant SAPⅣwere not affected when His-tag was placed at different end of the peptide.Meanwhile, at the same does of 2.71×10^-2μmol/kg body weight, N-Tag_His-SAPⅣinhibited the 39.40%（p＜0.01） of the twisting action of the mice induced by acetic acid while the inhibition ratio of N-Tag_His-SAPⅣ-1 and N-Tag_His-SAPⅣ-2 was 32.05%（p＜0.01） and 14.14%（p＜0.05） respectively. By SPSS test, It showed that there were no significant differences between N-Tag_His-SAPⅣand N-Tag_His-SAPⅣ-1; but there were significant differences between N-Tag_His-SAPⅣ-1 and N-Tag_His-SAPⅣ-2.