Structural studies of the lipid components of bile

The lipid-rich molecular aggregates responsible for the transport of cholesterol in bile include mixed micelles and bilayer vesicles. In this review, the molecular conformations of the individual lipid components of biliary micelles and vesicles (phospholipids, bile salts and cholesterol) obtained by high-resolution x-ray crystallographical analysis are described. The key conformational/packing features relevant to lipid organization, molecular interactions and cholesterol solubility in bile are discussed. The structure of cholesterol monohydrate, the major component in cholesterol gallstones, is described and problems relevant to cholesterol crystal nucleation/growth processes are briefly discussed.