In vitro studies on the interaction between bile salts and key enzymes of the liver.

Interactions between bile salts and cellular constituents are of considerable significance in studies on cholestasis. The main points of interest are the effects of the various bile salts on lipid and protein structures. Of primary interest are the interactions with lipids since these can cause disorder in cellular metabolism by eliminating compartmentalization. Conformational changes of proteins can occur through interactions with bile salts. They can involve specific functions. Of special importance here are the enzymes, since these are decisive supportive agents in cellular processes. In this paper, the effect of various bile salts on the activity of key hepatic enzymes was studied. In addition to the kinetic tests for enzyme activity, structural changes of the enzymes were studied as well using electrophoretic techniques. It could be shown that even much lower bile salt concentrations than those which occur in bile can lead to a complete inhibition of activity. The varying sensitivities of different enzymes when they react in the presence of bile salts is striking. According to the degree of hydroxylation, the various bile salts show characteristic differences in inhibitory effect on enzymatic activity. On the basis of the results reported here, it is quite possible that the interaction between bile salts and enzymes is a participating factor in the etiology and pathogenesis of cholestatic hepatic changes.