Document Detail

Structure and dynamics of cholic acid and dodecylphosphocholine-cholic acid aggregates.
MedLine Citation:
PMID:  20695585     Owner:  NLM     Status:  MEDLINE    
Bile acids are powerful detergents that emulsify and solubilize lipids, vitamins, cholesterol and other molecules in the biliary tract and intestines. It has long been known that bile acids form soluble mixed micelles with lipids. However, the detailed thermodynamic and structural properties of these micelles are not fully understood. This study sheds light on this issue based on results from multiple molecular dynamics simulations of cholic acid (CA) and dodecylphosphocholine (DPC) mixed micelles. We found that CA molecules form aggregates of up to 12 monomers with a mean size of 5-6. In agreement with several previous simulations and earlier predictions, the overall shape of these CA clusters is oblate disk-like such that the methyl groups point toward the core of the aggregate and the hydroxyl groups point away from it. The self-aggregation behavior of the CA clusters in the DPC-CA mixture is similar to the pure CA. Furthermore, the sizes and aggregation numbers of the DPC-CA mixed micelles are linearly dependent on CA molarity. In agreement with the radial shell model of Nichols and Ozarowski [Nichols, J. W.; Ozarowski, J. Biochemistry 1990, 29, 4600], our results demonstrate that CA molecules form a wedge between the DPC molecules with their hydroxyl and carboxyl groups facing the aqueous phase while their methyl groups are buried in and face the hydrocarbon core of the DPC micelle. The DPC-CA micelles simulated here tend to be spherical to prolate in shape, with the deviation from spherical geometry significantly increasing with increasing CA:DPC ratio.
Abdallah Sayyed-Ahmad; Lenard M Lichtenberger; Alemayehu A Gorfe
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Langmuir : the ACS journal of surfaces and colloids     Volume:  26     ISSN:  1520-5827     ISO Abbreviation:  Langmuir     Publication Date:  2010 Aug 
Date Detail:
Created Date:  2010-08-10     Completed Date:  2010-11-22     Revised Date:  2014-09-22    
Medline Journal Info:
Nlm Unique ID:  9882736     Medline TA:  Langmuir     Country:  United States    
Other Details:
Languages:  eng     Pagination:  13407-14     Citation Subset:  IM    
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MeSH Terms
Cholic Acid / chemistry*
Molecular Dynamics Simulation
Molecular Structure
Phosphorylcholine / analogs & derivatives*,  chemistry
Grant Support
Reg. No./Substance:
0/Micelles; 107-73-3/Phosphorylcholine; 53949-18-1/dodecylphosphocholine; G1JO7801AE/Cholic Acid

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