Document Detail


Nuclear Overhauser enhancement spectroscopy cross-relaxation rates and ethanol distribution across membranes.
MedLine Citation:
PMID:  11867455     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Measurement of nuclear Overhauser enhancement spectroscopy cross-relaxation rates between ethanol and palmitoyloleoylphosphatidylcholine bilayers was combined with atomic-level molecular dynamics simulations. The molecular dynamics trajectories yielded autocorrelation functions of proton dipole-dipole interactions, and, consequently, relaxation times and cross-relaxation rates. These analyses allow the measured cross-relaxation rates to be interpreted in terms of relative interaction strengths with the various segments of the lipid molecule. We determined that cross-relaxation between ethanol and specific lipid resonances is primarily determined by the sites of interaction with some modulation due to lipid disorder and to local differences in intramolecular lipid dynamics. The rates scale linearly with the lifetime of temporary ethanol-lipid associations. Ethanol interacts with palmitoyloleoylphosphatidylcholine bilayers primarily via hydrophilic interactions, in particular the formation of hydrogen bonds to the lipid phosphate group. There is a weak contribution to binding from hydrophobic interaction with lipid chain segments near the glycerol. However, the strength of hydrophobic interactions is insufficient to compensate for the energetic loss of locating ethanol in an exclusively hydrophobic environment, resulting in a probability of locating ethanol in the bilayer center that is three orders of magnitude lower than locating ethanol at the lipid/water interface. The low cross-relaxation rates between terminal methyl protons of hydrocarbon chains and ethanol are as much the result of infrequent chain upturns as of brief excursions of ethanol into the region of lipid hydrocarbon chains near the glycerol. The combination of nuclear magnetic resonance measurements and molecular dynamics simulations offers a general pathway to study the interaction of small molecules with the lipid matrix at atomic resolution.
Authors:
Scott E Feller; Christopher A Brown; David T Nizza; Klaus Gawrisch
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Biophysical journal     Volume:  82     ISSN:  0006-3495     ISO Abbreviation:  Biophys. J.     Publication Date:  2002 Mar 
Date Detail:
Created Date:  2002-02-27     Completed Date:  2002-06-25     Revised Date:  2010-09-14    
Medline Journal Info:
Nlm Unique ID:  0370626     Medline TA:  Biophys J     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1396-404     Citation Subset:  IM    
Affiliation:
Department of Chemistry, Wabash College, Crawfordsville, Indiana 47933, USA.
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MeSH Terms
Descriptor/Qualifier:
Biophysics / methods*
Cell Membrane / drug effects*
Ethanol / pharmacology*
Lipid Bilayers / metabolism
Lipids / chemistry
Magnetic Resonance Spectroscopy / methods*
Models, Molecular
Models, Statistical
Software
Time Factors
Chemical
Reg. No./Substance:
0/Lipid Bilayers; 0/Lipids; 64-17-5/Ethanol
Comments/Corrections

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