title: Dimorphism in bile salt/lecithin mixed micelles.
abstract: We investigated the dependence of certain properties of bile salt/lecithin mixed micelles on the molar ratio of the two components. UV absorption suggested that the micellar system is fundamentally altered on passing through a bile salt:lecithin molar ratio of 1.8:1. Differential scanning calorimetry confirmed this transition ratio; in addition, it indicated a bilayer arrangement of lecithin, in support of the mixed-disk model of micellar structure, but only for micelles having a molar ratio less than 1.8:1. For micelles having larger ratios, which are those of physiological interest, calorimetry was inconsistent with the mixed-disk model. These observations support the X-ray structure analysis of Müller.
mesh_terms: D001647:Bile Acids and Salts; D002152:Calorimetry, Differential Scanning; D055598:Chemical Phenomena; D002621:Chemistry; D003102:Colloids; D005782:Gels; D008823:Micelles; D008968:Molecular Conformation; D010713:Phosphatidylcholines; D013056:Spectrophotometry, Ultraviolet; D013329:Structure-Activity Relationship
chemical_list: D001647:Bile Acids and Salts; D003102:Colloids; D005782:Gels; D008823:Micelles; D010713:Phosphatidylcholines