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rdf:type |
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lifeskim:mentions |
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pubmed:issue |
2
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pubmed:dateCreated |
2005-7-28
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pubmed:abstractText |
Interactions of cholesterol (cho) with different lipids are commonly believed to play a key role in the formation of functional domains in membranes. We introduce a novel approach to characterize cho-lipid interactions by isothermal titration calorimetry. Cho is solubilized in the aqueous phase by reversible complexation with methyl-beta-cyclodextrin (cyd). Uptake of cho into the membrane is measured upon a series of injections of lipid vesicles into a cyd/cho solution. As an independent assay, cho release from membranes is measured upon titrating lipid/cho mixed vesicles into a cyd solution. The most consistent fit to the data is obtained with a mole fraction (rather than mole ratio) partition coefficient and considering a cho/cyd stoichiometry of 1:2. The results are discussed in terms of contributions from 1), the transfer of cho from cyd into a hypothetical, ideally mixed membrane and 2), from nonideal interactions with POPC. The latter are exothermic but opposed by a strong loss in entropy, in agreement with cho-induced acyl chain ordering and membrane condensation. They are accompanied by a positive heat capacity change which cannot be interpreted in terms of the hydrophobic effect, suggesting that additive-induced chain ordering itself increases the heat capacity. The new assays have a great potential for a better understanding of sterol-lipid interactions and yield suggestions how to optimize cho extraction from membranes.
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pubmed:commentsCorrections |
http://linkedlifedata.com/resource/pubmed/commentcorrection/15923231-10076038,
http://linkedlifedata.com/resource/pubmed/commentcorrection/15923231-10096908,
http://linkedlifedata.com/resource/pubmed/commentcorrection/15923231-10398929,
http://linkedlifedata.com/resource/pubmed/commentcorrection/15923231-10465761,
http://linkedlifedata.com/resource/pubmed/commentcorrection/15923231-10889017,
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http://linkedlifedata.com/resource/pubmed/commentcorrection/15923231-11090819,
http://linkedlifedata.com/resource/pubmed/commentcorrection/15923231-11090825,
http://linkedlifedata.com/resource/pubmed/commentcorrection/15923231-11566796,
http://linkedlifedata.com/resource/pubmed/commentcorrection/15923231-11694269,
http://linkedlifedata.com/resource/pubmed/commentcorrection/15923231-12124283,
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http://linkedlifedata.com/resource/pubmed/commentcorrection/15923231-12414701,
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http://linkedlifedata.com/resource/pubmed/commentcorrection/15923231-14507704,
http://linkedlifedata.com/resource/pubmed/commentcorrection/15923231-14622593,
http://linkedlifedata.com/resource/pubmed/commentcorrection/15923231-14979721,
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http://linkedlifedata.com/resource/pubmed/commentcorrection/15923231-9860844
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pubmed:language |
eng
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pubmed:journal |
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pubmed:citationSubset |
IM
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pubmed:chemical |
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pubmed:status |
MEDLINE
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pubmed:month |
Aug
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pubmed:issn |
0006-3495
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pubmed:author |
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pubmed:issnType |
Print
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pubmed:volume |
89
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
1109-19
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pubmed:dateRevised |
2009-11-18
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pubmed:meshHeading |
pubmed-meshheading:15923231-Calorimetry,
pubmed-meshheading:15923231-Cholesterol,
pubmed-meshheading:15923231-Computer Simulation,
pubmed-meshheading:15923231-Cyclodextrins,
pubmed-meshheading:15923231-Lipid Bilayers,
pubmed-meshheading:15923231-Membrane Fluidity,
pubmed-meshheading:15923231-Membrane Microdomains,
pubmed-meshheading:15923231-Models, Chemical,
pubmed-meshheading:15923231-Phase Transition,
pubmed-meshheading:15923231-Phosphatidylcholines,
pubmed-meshheading:15923231-Thermodynamics
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pubmed:year |
2005
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pubmed:articleTitle |
Interactions of cholesterol with lipid membranes and cyclodextrin characterized by calorimetry.
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pubmed:affiliation |
Biozentrum of the University of Basel, Division of Biophysical Chemistry, Switzerland.
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pubmed:publicationType |
Journal Article,
Research Support, Non-U.S. Gov't,
Evaluation Studies
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