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| Predicate | Object |
|---|---|
| rdf:type | |
| lifeskim:mentions | |
| pubmed:issue |
2
|
| pubmed:dateCreated |
1987-3-5
|
| pubmed:abstractText |
Differential scanning calorimetry (DSC) and X-ray diffraction have been used to study hydrated N-lignocerylgalactosylsphingosine (NLGS) bilayers. DSC of fully hydrated NLGS shows an endothermic transition at 69-70 degrees C, immediately followed by an exothermic transition at 72-73 degrees C; further heating shows a high-temperature (Tc = 82 degrees C), high-enthalpy (delta H = 15.3 kcal/mol NLGS) transition. Heating to 75 degrees C, cooling to 20 degrees C and subsequent reheating shows no transitions at 69-73 degrees C; only the high-temperature (82 degrees C), high-enthalpy (15.3 kcal/mol) transition. Two exothermic transitions are observed on cooling; for the upper transition its temperature (about 65 degrees C) and enthalpy (about 6 kcal/mol NLGS) are essentially independent of cooling rate, whereas the lower transition exhibits marked changes in both temperature (30----60 degrees C) and enthalpy (2.2----9.5 kcal/mol NLGS) as the cooling rate decreases from 40 to 0.625 Cdeg/min. On reheating, the enthalpy of the 69-70 degrees C transition is dependent on the previous cooling rate. The DSC data provide clear evidence of conversions between metastable and stable forms. X-ray diffraction data recorded at 26, 75 and 93 degrees C show clearly that NLGS bilayer phases are present at all temperatures. The X-ray diffraction pattern at 75 degrees C shows a bilayer periodicity d = 65.4 A, and a number of sharp reflections in the wide-angle region indicative of a crystalline chain packing mode. This stable bilayer form converts to a liquid-crystal bilayer phase; at 93 degrees C, the bilayer periodicity d = 59.1 A, and a diffuse reflection at 1/4.6 A-1 is observed. The diffraction pattern at 22 degrees C represents a combination of the stable and metastable low-temperature bilayer forms. NLGS exhibits a complex pattern of thermotropic changes related to conversions between metastable (gel), stable (crystalline) and liquid-crystalline bilayer phases. The structure and thermotropic properties of NLGS are compared with those of hydrated N-palmitoylgalactosylsphingosine reported previously (Ruocco, M.J., Atkinson, D., Small, D.M., Skarjune, R.P., Oldfield, E. and Shipley, G.G. (1981) Biochemistry 20, 5957-5966).
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| pubmed:grant | |
| pubmed:language |
eng
|
| pubmed:journal | |
| pubmed:citationSubset |
IM
|
| pubmed:chemical | |
| pubmed:status |
MEDLINE
|
| pubmed:month |
Jan
|
| pubmed:issn |
0006-3002
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| pubmed:author | |
| pubmed:issnType |
Print
|
| pubmed:day |
26
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| pubmed:volume |
896
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| pubmed:owner |
NLM
|
| pubmed:authorsComplete |
Y
|
| pubmed:pagination |
153-64
|
| pubmed:dateRevised |
2008-11-21
|
| pubmed:meshHeading |
pubmed-meshheading:3801466-Calorimetry, Differential Scanning,
pubmed-meshheading:3801466-Cerebrosides,
pubmed-meshheading:3801466-Chemistry, Physical,
pubmed-meshheading:3801466-Galactosylceramides,
pubmed-meshheading:3801466-Lipid Bilayers,
pubmed-meshheading:3801466-Membrane Lipids,
pubmed-meshheading:3801466-Physicochemical Phenomena,
pubmed-meshheading:3801466-Thermodynamics,
pubmed-meshheading:3801466-X-Ray Diffraction
|
| pubmed:year |
1987
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| pubmed:articleTitle |
Structure and metastability of N-lignocerylgalactosylsphingosine (cerebroside) bilayers.
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| pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, P.H.S.
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