Free energies of stable and metastable pores in lipid membranes under tension.
The free energy profile of pore formation in a lipid membrane, covering the entire range from a density fluctuation in an intact bilayer to a large tension-stabilized pore, has been calculated by molecular dynamics simulations with a coarse-grained lipid model. Several fixed elongations are used to obtain the Helmholtz free energy as a function of pore size for thermodynamically stable, metastable, and unstable pores, and the system-size dependence of these elongations is discussed. A link to the Gibbs free energy at constant tension, commonly known as the Litster model, is established by a Legendre transformation. The change of genus upon pore formation is exploited to estimate the saddle-splay modulus or Gaussian curvature modulus of the membrane leaflets. Details are provided of the simulation approach, which combines the potential of mean constraint force method with a reaction coordinate based on the local lipid density.
den Otter
Wouter K
WK
Computational Biophysics, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands. w.k.denotter@utwente.nl
D022082:Cellular Structures / Q000469:parasitology / Q000528:radiation effects; D004548:Elasticity / Q000502:physiology*; D019277:Entropy; D008051:Lipid Bilayers / Q000737:chemistry*; D018272:Porins / Q000502:physiology*; D012869:Skin Absorption / Q000502:physiology*; D055672:Static Electricity; D013314:Stress, Mechanical; D013500:Surface Tension / Q000187:drug effects / Q000528:radiation effects; D013696:Temperature
D008051:Lipid Bilayers; D018272:Porins