[Artificial chaperone-assisted refolding of recombined chicken Interleukin-18 gene in E.coli]

To study the technique of boosting the renaturation yield of rChIL-18 by using artificial molecular chaperone composed of cetyl trimethyl ammonium bromide (CTAB) and beta-cyclodextrin(beta-CD).

The recombinant plasmid of mChIL-18 prokaryotic expression was transformed into E.coli BL21 (DE3) strain and then induced by IPTG at 37 degrees Celsius. The recombinant mChIL-18 was expressed efficiently in inclusion bodies in E.coli. After crushed and washed, the inclusion bodies were thoroughly denatured with 6 mol/L of guanidine hydrochloride, and then the artificial molecular chaperone was used to promote protein refolding. After the rehabilitation of products was purified by bag filter, its activity was detected by lymphocyte proliferation assays.

The SDS-PAGE analysis indicated the expressed ChIL-18 protein had molecular weight of 44000. The expressed product existed in the form of inclusion body.Two protein bands of Mr 44000 and 26000 appeared on SDS-PAGE gel. The percentage of renaturation was 42.54 with artificial molecular chaperone.The results of MTT assay showed the expression of ChIL-18 protein in E.coli BL21 (DE3) greatly induced the proliferation of chicken T lymphocytes.

The artificial chaperone technique can obviously boost the renaturation yield of rChIL-18. The purified and expressed product of fusion chicken Interleukin-18 gene in E.coli have relativity high bioactivity.