Linked Life Data

1525164

Source:http://linkedlifedata.com/resource/pubmed/id/1525164

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
35
pubmed:dateCreated
1992-10-16
pubmed:abstractText
The gel-fluid phase equilibrium in a two-component system formed from dimyristoylphosphatidylcholine (DMPC) and distearoylphosphatidylcholine (DSPC) was investigated using solid-state wide-line 2H NMR spectroscopy. Analysis of the spectral first moments and the quantitation of gel and fluid phases by means of difference spectroscopy provided the temperature-composition phase diagrams. Phase diagrams were constructed for mixtures of perdeuterated DMPC, DMPC-d54, with DSPC and for the complementary system comprised of DMPC and perdeuterated DSPC, DSPC-d70. The gel-fluid coexistence region was found to extend over a wider range of temperature and composition for the DMPC-d54-DSPC system than for the DMPC-DSPC-d70 system. Comparison of these data with the phase diagram for the DMPC-DSPC system showed that in the gel-fluid region the fraction of lipids in the fluid phase at a given temperature and system composition decreases for the three systems in the order DMPC-d54-DSPC greater than DMPC-DSPC greater than DMPC-DSPC-d70. While the fluid fraction varies by as much as 90% among the three systems, the composition of the fluid phase, i.e., the ratio of the concentrations of the two molecules in the fluid phase, varies by about 20% over the whole temperature and system composition range. The effective acyl chain lengths of the DMPC-d54 and DSPC-d70 molecules as a function of temperature and composition in the fluid phase, when the system is all fluid or is in the gel-fluid coexistence region, were calculated from the quadrupole splittings in the axially symmetric powder patterns obtained for the all-fluid phase. The magnitudes of the coefficient of thermal expansion for both the DMPC-d54 and the DSPC-d70 molecules were smaller in the fluid phase of binary mixtures than in one-component bilayers containing either DSPC-d70 or DMPC-d54 alone. In addition, at any given temperature in the fluid phase, the increase in the acyl chain length of DMPC-d54 with increasing DSPC content of the system was smaller than the concomitant increase in the length of DSPC-d70 in mixtures with DMPC. In the entire temperature and composition range when the binary mixtures are in the all-fluid or in the gel-fluid coexistence region, the largest value obtained for the DMPC-d54 molecule in the fluid phase was smaller than the smallest value obtained for the DSPC-d70 molecule in the fluid phase. The acyl chain lengths were used to calculate the effective weighted-average thickness, d, of the fluid phase bilayer.(ABSTRACT TRUNCATED AT 400 WORDS)
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
8
pubmed:volume
31
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
8258-68
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1992
pubmed:articleTitle
Deuterium magnetic resonance study of phase equilibria and membrane thickness in binary phospholipid mixed bilayers.
pubmed:affiliation
Department of Biochemistry, University of Virginia Health Sciences Center, Charlottesville 22908.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.