periplasmic expression of a novel human bone morphogenetic protein-7 mutant in escherichia coli

background: bone morphogenetic proteins (bmps) belong to the transforming growth factor-β (tgf-β) superfamily, and play an important role in bone metabolism. recombinant forms of bmp-2 and bmp-7 are the only bmps used clinically. in this study the mature part of human bone morphogenetic protein-7 (bmp-7) was engineered through substitution of the bmp-7 n-terminal sequence by heparin-binding site of bmp-2. this targeted substitution was made to enhance the binding affinity of the novel protein to the extracellular matrix components such as heparin and heparan sulfate proteoglycans (hspgs). methods: the engineered protein was expressed in escherichia coli (e.coli). the pelb signal sequence was used to translocate soluble pro¬teins into the periplasmic space of e.coli. the protein was purified from periplasmic extract using ni-nta chromatography and the sds-page and western blot analysis confirmed the successful expression of the novel protein. results: the novel hbmp-7 mutant was produced as approximately 16 kda monomer. it was found that the heparin binding of this protein was approximately 50% more than that of the wild-type at a protein concentration of 500 ng/ml. conclusion: the findings showed that the periplasmic expression may be suitable to produce complex proteins like bmps.