Enthalpy of bile salt-lecithin mixed micelle formation

The enthalpies for the dissolution of lecithin by sodium salts of cholic, deoxycholic, and chenodeoxycholic acids and their glycine and taurine conjugates are reported. Exothermic enthalpies were found in each case. It is suggested that heat evolution is due to a bile salt-lecithin interaction other...

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Bibliographic Details
Published inJournal of pharmaceutical sciences Vol. 68; no. 5; p. 581
Main Authors Zimmerer, Jr, R O, Lindenbaum, S
Format Journal Article
LanguageEnglish
Published United States 01.05.1979
Subjects
Bile Acids and Salts
Micelles
Models, Chemical
Phosphatidylcholines
Solubility
Thermodynamics
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Summary:The enthalpies for the dissolution of lecithin by sodium salts of cholic, deoxycholic, and chenodeoxycholic acids and their glycine and taurine conjugates are reported. Exothermic enthalpies were found in each case. It is suggested that heat evolution is due to a bile salt-lecithin interaction other than hydrophobic interactions. These results provide strong support for the "mixed disk" model for the complex lecithin-bile salt micelle, which requires that a substantial fraction of the bile salt molecules be incorporated within a lecithin bilayer where hydrogenbonded pair formation can occur. Calorimetric studies of the interaction between sodium cholate and nonionic, cationic, and anionic detergents yielded exothermic heats. These results suggest that these bile salt molecules partition into the detergent micelle interior as hydrogenbonded pairs.
ISSN:0022-3549
DOI:10.1002/jps.2600680517