Entropy-driven softening of fluid lipid bilayers by alamethicin

  1. Get@NRC: Entropy-driven softening of fluid lipid bilayers by alamethicin (Opens in a new window)
DOIResolve DOI: http://doi.org/10.1021/la701586c
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Journal titleLangmuir
Pages1170511711; # of pages: 7
Subjectalamethicin; anti-bacterial agents; calorimetry; entropy; lipid Bilayers; membrane fluidity; phosphatidylcholines; scattering, small angle; x-ray diffraction
AbstractUsing dilatometry and small-angle X-ray diffraction, we have studied under bulk conditions the structural changes and elastic response of dioleoyl phosphatidylcholine bilayers to alamethicin. With increasing peptide concentration, we found a progressive thinning of the membrane. However, in contrast to previously published reports, this thinning exhibits exponential behavior. Furthermore, an increase in alamethicin content resulted in an increased lateral area per lipid and a swelling of the multibilayers which can be attributed to a decrease in the bilayer's bending rigidity by approximately 50%. At the same time, hydration and van der Waals forces remained unaffected by the presence of the peptide. Interestingly, all elastic and structural parameters followed the same exponential form found for the membrane thickness, implying a common underlying mechanism for all of these structural parameters. Our results can be understood by introducing an additional entropy term into the free-energy description of peptide incorporation, a term previously not considered. As a result, we have been able to reconcile recent controversies regarding the effect of peptides on membrane thinning.
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AffiliationNational Research Council Canada; NRC Canadian Neutron Beam Centre
Peer reviewedNo
NPARC number12327478
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Record identifierb0f51533-5c0e-4cd6-8f5b-663dacd66a3d
Record created2009-09-10
Record modified2016-05-09
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