A Simple and Rapid Method for Expression and Purification of Functional TNF-alpha Using GST Fusion System

Abstract

Tumor necrosis factor alpha (TNF-alpha) is an inflammatory cytokine, involved in both physiological and pathological pathways. Although there have been various attempts to express and purify human TNF-alpha, the current work introduces a simple, rapid, and efficient method for its production without loss of biological activity. The protein was expressed based on GST-tagged fusion system in Escherichia coli under optimized condition. The expressed GST fusion protein was applied to glutathione affinity column and then, TNF-alpha was cleaved off the GST using thrombin protease. The purity of the product was more than 95% and further size exclusion chromatography slightly improved the purity. The purified human TNF-alpha was tested for its biological activity and structural analysis, using MTT assay (EC50 of 4.1 x10E-12 M in L929 cell death assay) and circular dichroism spectropolarimetry, respectively. The results showed that the method used in this study enables successful production of highly purified and fully functional TNF-alpha.