Interaction of Phosphoproteins with Calcium Phosphate

Abstract

Highly phosphorylated phosphoproteins are associated with many types of mineralization processes in biology. The binding of phosphoproteins to mineral surfaces and their action in controlling the precipitation of salts from solution are little understood, particularly with regard to the influence of the structure of the proteins on their biological function. The casein phosphoproteins occur naturally in milk as large particles called casein micelles which scatter light strongly. In these micelles, the caseins are linked through their phosphate groups to a very highly dispersed amorphous calcium phosphate which cements the protein monomers together. It is possible, therefore, that the proteins have a different conformation in the native casein micelle than in solution, free of calcium phosphate. Accordingly, a study of the infrared spectra of casein micelles and casein in free solution has begun and preliminary results are available.