The nature of bone morphogenetic protein (BMP) fractions derived from bovine bone matrix gelatin

A bone morphogenetic protein (BMP) fraction consisting of 17.5K, as well as three other low MW components, was extracted from demineralized bovine bone matrix gelatin under dissociative conditions in 4 M GuHCl. This BMP fraction induces differentiation of mesenchymal cells into cartilage and bone when implanted in the thigh muscles of mice. The 17.5K component is a prime candidate for BMP, but the relationship to the 34K, 24K, and 14K components is not established completely. The 24K component is of special interest, because, when it is present in combination with 17.5K and other components, the resultant preparation has high biologic activity. The 24K component, when isolated from the 17.5K component, had no BMP activity. The 14K component, when isolated from the 17.5K component and all components, had no BMP activity. A 22K components completely isolated by CMC chromatography had no BMP activity. The tasks ahead are to examine further the conditions controlling aggregation of the four low MW glycoproteins and to determine whether it is possible to isolate a single 17.5K homogeneous polypeptide with BMP activity.