Expression, purification and refolding of recombinant human bone morphogenetic protein- 2 in Escherichia coli

AIM: To get high biological activity of recombinant human bone morphogenetic protein-2 (rhBMP-2) expressed in Escherichia coli by the methods of refolding. METHODS: The rhBMP-2, expressed in Escherichia coli, was washed by Triton X-100 and further purified by DEAE chromatography. The inclusion bodies were resolved in 8 mol/L urea,and were refolded and dimerized in the redox systems (reduced and oxidized glutathione). Finally, a one-step purification procedure based on the heparin affinity chromatography was implemented. The biological activity of purified rhBMP-2 were tested by induction of the alkaline phosphatase activity in C2C12 cells. RESULTS: The rhBMP-2 was expressed in Escherichia coli in a non-active aggregated form of inclusion bodies using a temperature-inducible expression system. The high-purified rhBMP-2 was obtained in the form of inclusion bodies by several purification courses. The rhBMP-2 was refolded and dimerized in the redox systems (reduced and oxidized glutathione) and a one-step purification procedure based on the heparin affinity chromatography was implemented to isolate the rhBMP-2 dimers and monomers. The purified rhBMP-2 dimers showed the higher biological activity than the commercial rhBMP-2. CONCLUSIONS: The method achieved the refolding of rhBMP-2 would be applied to the whole TGF-β superfamily because the BMP-2 belongs to the superfamily. Meanwhile, the inexpensive, high yield rhBMP-2 is suitable for clinic application.