Source:http://linkedlifedata.com/resource/pubmed/id/15670735
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| Predicate | Object |
|---|---|
| rdf:type | |
| lifeskim:mentions | |
| pubmed:issue |
1
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| pubmed:dateCreated |
2005-1-26
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| pubmed:abstractText |
A full description of coexisting phases includes their respective compositions, which are provided by the thermodynamic tie-lines. Fluorescence microscopy enables visualization of coexisting lipid phases in giant unilamellar phases, but the composition information is missing. For cholesterol-containing lipid mixtures, knowledge of the compositions of the coexisting phases is important for understanding the nature of "membrane rafts". We propose and demonstrate a new method, based on ESR spectroscopy, for determining tie-lines in regions of two-phase coexistence in a ternary lipid mixture. Over 100 different lipid compositions containing the spin-labeled phospholipid 16-PC in or near the two-phase coexistence region of the liquid-disordered and the gel phases of dipalmitoyl-PC/dilauroyl-PC/cholesterol (DPPC/DLPC/Chol) were studied to determine five tie-lines, spread over virtually the full range of this coexistence region. The method is based on the facts that (1) along a tie-line the ESR spectrum must be a superposition of the two ESR spectra from the respective single phases at the phase boundaries (connected by the tie-line) in a ratio given by the lever rule; (2) along a tie-line the partition coefficient, K(p), for the spin-label, which is also determined in our method, must be constant. We do find that K(p) for 16-PC is close to unity, but its value depends on the particular tie-line. The coexisting phases in equilibrium are characterized by the K(p) of the spin-label and its respective dynamic parameters obtained from fitting the ESR spectra to dynamical models.
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| pubmed:language |
eng
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| pubmed:journal | |
| pubmed:citationSubset |
IM
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| pubmed:chemical | |
| pubmed:status |
MEDLINE
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| pubmed:month |
Feb
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| pubmed:issn |
0006-3002
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| pubmed:author | |
| pubmed:issnType |
Print
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| pubmed:day |
1
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| pubmed:volume |
1668
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| pubmed:owner |
NLM
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| pubmed:authorsComplete |
Y
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| pubmed:pagination |
99-105
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| pubmed:dateRevised |
2006-4-17
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| pubmed:meshHeading | |
| pubmed:year |
2005
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| pubmed:articleTitle |
New method for determining tie-lines in coexisting membrane phases using spin-label ESR.
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| pubmed:affiliation |
Baker Laboratory of Chemistry and Chemical Biology, and National Biomedical ACERT Center for Advanced ESR Technology, Cornell University, Ithaca, New York 14853-1301, USA.
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| pubmed:publicationType |
Journal Article
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