Expression of C-terminal Segment of Bone Morphogenetic Protein in E. coli

Two recombinant C-terminal segments of human bone morphogenetic protein 2A (BMP2A), designated as BMP23 (173 aa) and BMP24 (134 aa), were expressed under the control of P(L) promoter in E. coli. SDS-PAGE analysis showed two induced protein bands at 20 kD and 15.5 kD, which were about 10% and 20% of the total bacterial protein, respectively. Both the expressed proteins were insoluble aggregates, which reached 80% purity after rapid preparation of the products as the inclusion body. The results of N-terminal amino acid sequencing showed that the first 15amino acids at the N-terminal were identical to those encoded by the cDNA genes of both BMP24. After refolding both BMP23 and BMP24 formed disulfide-linked dimeric protein bands in SDS-PAGE. Bioassay in vivo revealed that BMP23 induced chondrocytes differentiation and BMP24 stimulated collagen synthesis.