Structural Aspects of Bile Salt-Lecithin Mixed Micelles

Mixed micells formed by the major constituents of native bile, i.e., bile salts and lecithin, were studied by X-ray scattering differential scanning calorimetry and electron spin resonance spectroscopy. The aim of this study was to find differences in micellar structure and thermodynamic properties which might explain the different abilities of various biles to keep cholesterol in solution at comparable degrees of oversaturation. The data indicate not only that different types of micelles exist but also that different types of complex bile salt/phospholipid arrangements exist within the micelles. It is speculated that the stabilizing and destabilizing factors found by other authors influence the balance between the different micellar structures and thereby the cholesterol solubilization power of bile.