Issue 15, 2014

Nanosecond lipid dynamics in membranes containing cholesterol

Abstract

Lipid dynamics in the cholesterol-rich (40 mol%) liquid-ordered (lo) phase of dimyristoylphosphatidylcholine membranes were studied using neutron spin-echo and neutron backscattering. Recent theoretical and experimental evidence supports the notion of the liquid-ordered phase in phospholipid membranes as a locally structured liquid, with small ordered ‘domains’ of a highly dynamic nature in equilibrium with a disordered matrix [S. Meinhardt, R. L. C. Vink and F. Schmid, Proc. Natl. Acad. Sci. U. S. A., 2013, 110(12), 4476–4481, C. L. Armstrong et al., PLoS One, 2013, 8(6), e66162]. This local structure was found to have a pronounced impact on the membranes' dynamical properties. We found that the long-wavelength dynamics in the liquid-ordered phase, associated with the elastic properties of the membranes, were faster by two orders of magnitude as compared to the liquid disordered phase. At the same time, collective nanoscale diffusion was significantly slower. The presence of a soft-mode (a slowing down) in the long-wavelength dispersion relationship suggests an upper size limit for the ordered lipid domain of ≈220 Å. Moreover, from the relaxation rate of the collective lipid diffusion of lipid–lipid distances, the lifetime of these domains was estimated to be about 100 nanoseconds.

Graphical abstract: Nanosecond lipid dynamics in membranes containing cholesterol

Article information

Article type
Paper
Submitted
26 Jun 2013
Accepted
10 Jan 2014
First published
10 Jan 2014

Soft Matter, 2014,10, 2600-2611

Nanosecond lipid dynamics in membranes containing cholesterol

C. L. Armstrong, W. Häußler, T. Seydel, J. Katsaras and M. C. Rheinstädter, Soft Matter, 2014, 10, 2600 DOI: 10.1039/C3SM51757H

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