Pigment binding of copper in human bile.

The copper profile of human bile was studied using a Cu-free preparative polyacrylamide gel system. 85 percent and 91 percent of the Cu in the bile of two subjects was found in a leading pigmented band with no additional detectable copper in the remainder of the gel in either subject. The content of the pigmented band was recovered from the gel by an intermediate electrophoretic technique. Subsequent n-butanol extraction removed contaminating bile salts with the formation of a Cu containing pigmented precipitate. Using thin-layer cellulose chromatography this precipitate was separated into two pigments which on the basis of color and diazotization reaction were believed to be conjugated bilirubins. Addition of Cu transformed the pigments into biochemically different species. 64Cu verified copper binding by the altered pigments.