Expression of wild-type and mutant interleukin-13 in E.coli and analysis of the biological activity

To express the recombinant wild-type human interleukin-13 and mutant interleukin-13 in E.coli and get protein with biological activity.The wilde-type interleukin-13 and mutant interleukin-13 gene were amplified from the plasmid of pET22bhIL -13 by PCR and site-directed mutagenesis PCR and were cloned into the expression plasmid vector of pET28a(+),respectively, to construct the expression plasmids,which were transformed into E.coli BL21(DE3).Expression of recombinant protein was induced by IPTG.Expression product was purified through Ni column(Ni-NTA).The purified proteins were renatured and the biological activity was analyzed.The result showed that the recombinant IL-13 and IL-13m were successfully expressed in the form of inclusion body with a relative molecular mass about 14.6 kD confirmed by SDS-PAGE,in accordance with the design.And the specificity was proved by Western-blot.The recombinant proteins were biological active after purification and renaturation.Thus,the recombinant IL-13 and IL-13m with bioactivity have been successfully obtained,which lays the foundation for research into their role on the asthmatic mechanism.