Differential binding of glycine- and taurine-conjugated bile acids to insoluble calcium phosphate.

It is demonstrated that bile acids bind to insoluble calcium phosphate at pH values beyond 5.5. Significant binding occurs with glycine-conjugated dihydroxy bile acids. Results indicate that these bile acids are bound in a micellar mode. Taurine conjugation almost completely inhibits the binding of these bile acids to insoluble calcium phosphate. Since glycine-conjugated dihydroxy bile acids are predominant in the rabbit, but not in the rat, our results suggest an explanation for the intriguing species-dependence of casein-induced hypercholesterolaemia, which is high in the rabbit but absent in the rat.