A study of endogenous N-cholylglycine distribution among serum proteins using radioimmunoassay

The amount of N-cholylglycine endogenously associated with the various protein fractions was assessed in serum of patients with hepatobiliary obstruction using a sensitive radioimmunoassay. In contrast to evidence obtained with cholate, the albumin fraction separated by electrophoresis was found to contain only 2.6% of the total N-cholylglycine, while the alpha 2 region had 64% associated with it. The serum beta-lipoprotein isolated by anionic precipitation also contained significant quantities of the conjugated bile acid, the amount in this fraction being greater in the serum of hyperlipidemic subjects. The results suggest that despite accounting for some 63% of the total serum protein, albumin is not the major carrier of endogenous N-cholylglycine in the circulation.