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Predicate | Object |
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rdf:type | |
lifeskim:mentions | |
pubmed:issue |
10
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pubmed:dateCreated |
1985-9-12
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pubmed:abstractText |
Calorimetric, X-ray diffraction, and 31P nuclear magnetic resonance (NMR) studies of aqueous dispersions of 1,2-dihexadecyl-sn-glycero-3-phosphocholine (DHPC) gel phases at low temperatures (-60 to 22 degrees C) show thermal, structural, and dynamic differences when compared to aqueous dispersions of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) gel phases at corresponding temperatures. Differential scanning calorimetry of DHPC dispersions demonstrates a reversible, low-enthalpy "subtransition" at 4 degrees C in contrast to the conditionally reversible, high-enthalpy subtransition observed at 17 degrees C for annealed DPPC bilayers. X-ray diffraction studies indicate that DHPC dispersions form a lamellar gel phase with dav congruent to 46 A both above and below the "subtransition". It is suggested that the reduced dav observed for DHPC (46 A as compared to 64 A in DPPC) is due to an interdigitated lamellar gel phase which exists at all temperatures below the pretransition at 35 degrees C. 31P NMR spectra of DHPC gel-phase bilayers show an axially symmetric chemical shift anisotropy powder pattern which remains sharp down to -20 degrees C, suggesting the presence of fast axial diffusion. In contrast, 31P spectra of DPPC bilayers indicate this type of motion is frozen out at approximately 0 degrees C.
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pubmed:grant | |
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 |
May
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pubmed:issn |
0006-2960
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pubmed:author | |
pubmed:issnType |
Print
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pubmed:day |
7
|
pubmed:volume |
24
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
|
pubmed:pagination |
2406-11
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pubmed:dateRevised |
2007-11-14
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pubmed:meshHeading |
pubmed-meshheading:3839412-Calorimetry,
pubmed-meshheading:3839412-Gels,
pubmed-meshheading:3839412-Magnetic Resonance Spectroscopy,
pubmed-meshheading:3839412-Molecular Conformation,
pubmed-meshheading:3839412-Pulmonary Surfactants,
pubmed-meshheading:3839412-Structure-Activity Relationship,
pubmed-meshheading:3839412-Thermodynamics,
pubmed-meshheading:3839412-X-Ray Diffraction
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pubmed:year |
1985
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pubmed:articleTitle |
Comparative study of the gel phases of ether- and ester-linked phosphatidylcholines.
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pubmed:publicationType |
Journal Article,
Comparative Study,
Research Support, U.S. Gov't, P.H.S.,
Research Support, U.S. Gov't, Non-P.H.S.,
Research Support, Non-U.S. Gov't
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