The Expression of Porcine Interleukin-18 Gene and the Purification of Its Recombinant Protein

The mature protein gene of porcine interleukin-18 was amplified from recombinant plasmid pcDNA3.1-IL18 by PCR.After being digested by restriction endonucleases,the IL-18 mature protein gene was subcloned(into) the prokaryotic expression vector pET41c and pET32c.After restriction enzyme digestion,PCR identification and sequence analysis of the recombinant plasmid,the positive recombinant plasmid was selected and designated as pET41c-IL18 and pET32c-IL18.The pET41c-IL18 and pET32c-IL18 were transformed into Escherichia coli BL_(21)(DE_3),and then induced with IPTG at 37 ℃ overnight.SDS-PAGE and Western-blotting analysis showed that the expressed recombinant IL-18 protein presented in inclusion bodies and was about 33 ku in molecular weight.Following denaturation with 8 mol/L urea,the recombinant IL-18 protein which was purified with NiNTA His Bind Resin was refolded by dialysis against PBS and water.