Linked Life Data

16529710

Source:http://linkedlifedata.com/resource/pubmed/id/16529710

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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
2006-5-12
pubmed:abstractText
We report on the effects of temperature and pressure on the structure, conformation and phase behavior of aqueous dispersions of the model lipid "raft" mixture palmitoyloleoylphosphatidylcholine (POPC)/bovine brain sphingomyelin (SM)/cholesterol (Chol) (1:1:1). We investigated interchain interactions, hydrogen bonding, conformational and structural properties as well as phase transformations of this system using Fourier transform-infrared (FT-IR) spectroscopy, small-angle X-ray scattering (SAXS), differential scanning calorimetry (DSC) coupled with pressure perturbation calorimetry (PPC), and Laurdan fluorescence spectroscopy. The IR spectral parameters in combination with the scattering patterns from the SAXS measurements were used to detect structural and conformational transformations upon changes of pressure up to 7-9 kbar and temperature in the range from 1 to about 80 degrees C. The generalized polarization function (GP) values, obtained from the Laurdan fluorescence spectroscopy studies also reveal temperature and pressure dependent phase changes. DSC and PPC were used to detect thermodynamic properties accompanying the temperature-dependent phase changes. In combination with literature fluorescence spectroscopy and microscopy data, a tentative p,T stability diagram of the mixture has been established. The data reveal a broad liquid-order/solid-ordered (lo+so) two-phase coexistence region below 8+/-2 degrees C at ambient pressure. With increasing temperature, a lo+ld+so three-phase region is formed, which extends up to approximately 27 degrees C, where a liquid-ordered/liquid-disordered (lo+ld) immiscibility region is formed. Finally, above 48+/-2 degrees C, the POPC/SM/Chol (1:1:1) mixture becomes completely fluid-like (liquid-disordered, ld). With increasing pressure, all phase transition lines shift to higher temperatures. Notably, the lo+ld (+so) phase coexistence region, mimicking raft-like lateral phase separation in natural membranes, extends over a rather wide temperature range of about 40 degrees C, and a pressure range, which extends up to about 2 kbar for T=37 degrees C. Interestingly, in this pressure range, ceasing of membrane protein function in natural membrane environments has been observed for a variety of systems.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0006-3002
pubmed:author
pubmed:issnType
Print
pubmed:volume
1758
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
248-58
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed-meshheading:16529710-2-Naphthylamine, pubmed-meshheading:16529710-Animals, pubmed-meshheading:16529710-Calorimetry, pubmed-meshheading:16529710-Calorimetry, Differential Scanning, pubmed-meshheading:16529710-Cattle, pubmed-meshheading:16529710-Cholesterol, pubmed-meshheading:16529710-Fluorescent Dyes, pubmed-meshheading:16529710-Laurates, pubmed-meshheading:16529710-Membrane Microdomains, pubmed-meshheading:16529710-Molecular Conformation, pubmed-meshheading:16529710-Phosphatidylcholines, pubmed-meshheading:16529710-Pressure, pubmed-meshheading:16529710-Scattering, Radiation, pubmed-meshheading:16529710-Spectrometry, Fluorescence, pubmed-meshheading:16529710-Spectroscopy, Fourier Transform Infrared, pubmed-meshheading:16529710-Sphingomyelins, pubmed-meshheading:16529710-Synchrotrons, pubmed-meshheading:16529710-Temperature, pubmed-meshheading:16529710-X-Rays
pubmed:year
2006
pubmed:articleTitle
Temperature and pressure effects on structural and conformational properties of POPC/SM/cholesterol model raft mixtures--a FT-IR, SAXS, DSC, PPC and Laurdan fluorescence spectroscopy study.
pubmed:affiliation
University of Dortmund, Department of Chemistry, Physical Chemistry I-Biophysical Chemistry, Otto-Hahn-Strasse 6, D-44227 Dortmund, Germany.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't