American Journal of Clinical Nutrition, Vol 24, 1025-1027, Copyright © 1971 by The American Society for Clinical Nutrition, Inc.

Binding of copper by human alimentary secretions

¹ From the Department of Medicine, The University of Adelaide, South Australia, 5001

A radioassay was developed for estimation of the copper complexing ability of biological fluids. Application of this test to human saliva, gastric juice, hepatic and gall bladder bile showed that each contained substances with the ability to bind copper and form soluble complexes under alkaline conditions. The affinity of gall bladder bile for the metal greatly exceeded that of the other secretions. Resolution of secretions labeled with ⁶⁴Cu by gel filtration indicated that the copper binding components of saliva and gastric juice form low molecular weight complexes. In contrast, bile contained a macromolecular binding component that was more pronounced in gall bladder than in hepatic bile. The net absorption of dietary copper in man may represent an interplay between the opposing influences of endogenous low molecular weight ligands and the macromolecular copper binding moiety in bile.