The Binding of Thorium(IV), Plutonium(IV), Americium(III) and Curium(III) to the Constituents of Bovine Cortical Bone In Vitro

By means of a gel filtration technique it has been shown that thorium (IV), plutonium (IV), americium (III) and curium (III) bind to five glycoprotein fractions isolated from bovine cortical bone and to certain other substances. The effects of pH on the binding of plutonium to poly-L-glutamic acid and to bone chondroitin sulfate and of curium to bone sialoprotein and chondroitin sulfate-protein complex are described. Plutonium, americium, and curium were found to bind to bone glycoproteins in the presence of a 30-fold greater mass of bone mineral than glycoprotein. Some experiments on the precipitation of calcium phosphate in vitro in the presence of plutonium and americium are also presented. These observations are discussed in the light of the hypothesis that certain actinide elements are localized at bone surfaces by binding to glycoproteins.