Linked Life Data

1649825

Source:http://linkedlifedata.com/resource/pubmed/id/1649825

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
21
pubmed:dateCreated
1991-8-23
pubmed:abstractText
Differential scanning calorimetry (DSC) and nuclear magnetic resonance (NMR) spectroscopy are applied to characterize the nonfreezable water molecules in fully hydrated D2O/sphingomyelin at temperatures below 0 degrees C. Upon cooling, DSC thermogram displays two thermal transitions peaked at -11 and -34 degrees C. The high-temperature exothermic transition corresponds to the freezing of the bulk D2O, and the low-temperature transition, which has not previously been reported, can be ascribed to the freezing of the phosphocholine headgroup in the lipid bilayer. The dynamics of nonfreezable water are also studied by 2H NMR T1 (spin-lattice relaxation time) and T2e (spin-spin relaxation time obtained by two pulse echo) measurements at 30.7 MHz and at temperatures down to -110 degrees C. The temperature dependence of the T1 relaxation time is characterized by a distinct minimum value of 2.1 +/- 0.1 ms at -30 degrees C. T2e is discontinuous at temperature around -70 degrees C, indicating another freezing-like event for the bound water at this temperature. Analysis of the relaxation data suggest that nonfreezable water undergoes both fast and slow motions at characteristic NMR time scales. The slow motions are affected when the lipid headgroup freezes.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
25
pubmed:volume
266
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
13602-6
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1991
pubmed:articleTitle
Freezing of phosphocholine headgroup in fully hydrated sphingomyelin bilayers and its effect on the dynamics of nonfreezable water at subzero temperatures.
pubmed:affiliation
Institute of Life Sciences, National Tsing Hua University, Hsinchu, Taiwan, Republic of China.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't