The physical properties of a glycoprotein from bovine cortical bone (bone sialoprotein)

Physicochemical studies have been made of two different preparations of bone sialoprotein, a glycoprotein from bovine cortical bone, which contains a high proportion of sialic acid groups. Determinations have been made of s⁰_20,w, diffusion coefficient, molecular weight, sedimentation coefficient distribution, optical rotatory dispersion curves, mobility during free boundary electrophoresis, partial specific volume and refractive index increment. The two preparations differed slightly in molecular weight, but both are small molecules, polydisperse but homogeneous with respect to centrifugation and electrophoresis. Their frictional coefficients are higher than that expected for globular molecules and they have little or no helical content. The results are discussed in the light of available analytical and structural information.