Effect of the cosolutes trehalose and methanol on the equilibrium and phase-transition properties of glycerol-monopalmitate lipid bilayers investigated using molecular dynamics simulations
Open access
Date
2014-11Type
- Journal Article
Abstract
The influence of the cosolutes trehalose and methanol on the structural, dynamic and thermodynamic properties of a glycerol-1-monopalmitate (GMP) bilayer and on its main transition temperature Tm is investigated using atomistic molecular dynamics simulations (600 ns) of a GMP bilayer patch (2 × 8 × 8 lipids) at different temperatures in the range of 302 to 338 K and considering three different cosolute concentrations. Depending on the environment and temperature, these simulations present no or a single GL→LC, LC→GL or LC→ID transition, where LC, GL and ID are the liquid crystal, gel and interdigitated phases, respectively. The trehalose molecules form a coating layer at the bilayer surface, promote the hydrogen-bonded bridging of the lipid headgroups, preserve the interaction of the headgroups with trapped water and induce a slight lateral expansion of the bilayer in the LC phase, observations that may have implications for the phenomenon of anhydrobiosis. However, this cosolute does not affect Tm and its dependence on hydration in the concentration range considered. On the other hand, methanol molecules intercalate between the lipid headgroups, promote a lateral expansion of the bilayer in the LC phase and induce a concentration dependent decrease of Tm, observations that may have implications for the phenomenon of anesthesia. The occurrence of an ID phase in the presence of this cosolute may be viewed as an extreme consequence of lateral expansion. The analysis of the simulations also suggests the existence of two basic conservation principles: (1) the hydrogen-bond saturation principle rests on the observation that for all species present in the different systems, the total numbers of hydrogen-bonds per molecule is essentially constant, the only factor of variability being their distribution among different partners; (2) the densest packing principle rests on the observation that the effective volume per methylene group in the interior of the bilayer is only weakly sensitive to the environment, with values comparable to those for liquid (LC) and solid (ID) alkanes, or intermediate (GL). © 2014, European Biophysical Societies' Association. Show more
Permanent link
https://doi.org/10.3929/ethz-b-000088293Publication status
publishedExternal links
Journal / series
European Biophysics JournalVolume
Pages / Article No.
Publisher
SpringerSubject
Molecular dynamics; Lipid bilayer; Monoglyceride; Glycerol monopalmitate; Phase transition; Trehalose; MethanolOrganisational unit
03449 - Merkt, Frédéric / Merkt, Frédéric
Notes
It was possible to publish this article open access thanks to a Swiss National Licence with the publisher.More
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