Analysis of bone morphogenetic protein (BMP) derived from human and bovine bone matrix

Recently, Bone Morphogenetic Protein (BMP) has attracted the attention of a number of investigators, but its elucidation remains incomplete. At present, the determination of its amino acid sequence, which is necessary for its synthesis, and screening for a carrier that allows BMP to be effective in small amounts are unsolved problems. Bone morphogenetic protein is studied here to clarify its clinical applications. BMP was extracted from human and bovine bone matrix with 4 M guanidine-HCl and purified by liquid chromatography. Acrylamide electrophoresis (SDS-PAGE) and isoelectric focusing (IEF) showed that the purified BMP was homogeneous. We used type I collagen as the carrier in the bioassay. This BMP induced new bone in situ three weeks after implantation in muscle pouches in Wistar rats. The molecular weights of human and bovine bone matrix-derived BMP are 17.0 and 18.0 kDa by SDS-PAGE, and pI values for both are 4.9 by IEF. Human and bovine bone matrix-derived BMP are peptides containing 165 and 163 amino acids, respectively, according to amino acid analysis. The NH2-terminal sequence of bovine bone matrix-derived BMP was obtained from the bovine band, electroblotted onto polyvinylidene difluoride membrane, that corresponded to the final purified fraction. The sequence differs from previously designated BMPs25 and other proteins reported to have similar activity, but the physicochemical characteristics are comparable to the native preparations.