Document Detail

Relating domain size distribution to line tension and molecular dipole density in model cytoplasmic myelin lipid monolayers.
MedLine Citation:
PMID:  21606329     Owner:  NLM     Status:  MEDLINE    
We fit the size distribution of liquid-ordered (L(o)) domains measured from fluorescence images of model cytoplasmic myelin monolayers with an equilibrium thermodynamic expression that includes the competing effects of line tension, λ, dipole density difference, Δm, and the mixing entropy. From these fits, we extract the line tension, λ, and dipole density difference, Δm, between the L(o) and liquid-disordered (L(d)) phases. Both λ and Δm decrease with increasing surface pressure, , although λ/Δm(2) remains roughly constant as the monolayer approaches the miscibility surface pressure. As a result, the mean domain size changed little with surface pressure, although the polydispersity increased significantly. The most probable domain radius was significantly smaller than that predicted by the energy alone, showing that the mixing entropy promotes a greater number of smaller domains. Our results also explain why domain shapes are stable; at equilibrium, only a small fraction of the domains are large enough to undergo theoretically predicted shape fluctuations. Monolayers based on the composition of myelin from animals with experimental allergic encephalomyelitis had slightly lower values of λ and Δm, and a higher area fraction of domains, than control monolayers at all . While it is premature to generalize these results to myelin bilayers, our results show that the domain distribution in myelin may be an equilibrium effect and that subtle changes in surface pressure and composition can alter the distribution of material in the monolayer, which will likely also alter the interactions between monolayers important to the adhesion of the myelin sheath.
Dong Woog Lee; Younjin Min; Prajnaparamitra Dhar; Arun Ramachandran; Jacob N Israelachvili; Joseph A Zasadzinski
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2011-05-23
Journal Detail:
Title:  Proceedings of the National Academy of Sciences of the United States of America     Volume:  108     ISSN:  1091-6490     ISO Abbreviation:  Proc. Natl. Acad. Sci. U.S.A.     Publication Date:  2011 Jun 
Date Detail:
Created Date:  2011-06-09     Completed Date:  2011-08-26     Revised Date:  2014-09-18    
Medline Journal Info:
Nlm Unique ID:  7505876     Medline TA:  Proc Natl Acad Sci U S A     Country:  United States    
Other Details:
Languages:  eng     Pagination:  9425-30     Citation Subset:  IM    
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MeSH Terms
Cytoplasm / chemistry,  metabolism
Hydrophobic and Hydrophilic Interactions
Image Processing, Computer-Assisted
Lipid Bilayers / chemistry*,  metabolism
Membrane Lipids / chemistry*,  metabolism
Membrane Microdomains / chemistry*,  metabolism
Membrane Proteins / chemistry,  metabolism
Microscopy, Fluorescence / methods
Models, Chemical
Models, Molecular
Myelin Sheath / chemistry*,  metabolism
Phosphatidylcholines / chemistry,  metabolism
Phosphatidylethanolamines / chemistry,  metabolism
Phosphatidylserines / chemistry,  metabolism
Sphingomyelins / chemistry,  metabolism
Grant Support
Reg. No./Substance:
0/Lipid Bilayers; 0/Membrane Lipids; 0/Membrane Proteins; 0/Phosphatidylcholines; 0/Phosphatidylethanolamines; 0/Phosphatidylserines; 0/Sphingomyelins; 39382-08-6/phosphatidylethanolamine

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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