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Giant Liposome Preparation for Imaging and Patch-Clamp Electrophysiology
Published on: June 21, 2013
Electrostatics of deformable lipid membranes
Igor Vorobyov1, Borislava Bekker, Toby W Allen
1Department of Chemistry, University of California, Davis, California, USA.
Biophysical Journal
|June 17, 2010
Summary
Hydration and electrostatics minimally impact membrane ion permeation, despite significant changes in ion solvation and membrane dipole potential. Membrane deformation plays a key role in regulating ion passage.
Area of Science:
- Biophysics
- Computational Biology
- Membrane Science
Background:
- Standard models of membrane electrostatics are challenged by observed local membrane deformations caused by charged peptides and ions.
- The role of ion hydration and electrostatics in membrane permeability requires re-evaluation due to insensitivity to ion type.
Purpose of the Study:
- To investigate the influence of hydration energetics and electrostatics on membrane ion permeation.
- To determine the impact of hydrocarbon electronic polarizability on ion solvation and membrane dipole potential.
- To understand the mechanisms behind membrane deformation and its effect on ion translocation.
Main Methods:
- Molecular simulations using methyl-guanidinium as a model ion.
- Analysis of ion solvation free energy and membrane dipole potential changes.
- Simulation of membrane defects and ionophores (valinomycin, gramicidin A) for comparison.
Main Results:
- Electronic polarizability significantly alters ion solvation energy and membrane dipole potential (~0.4 V).
- Despite these changes, membrane permeation energetics show minimal variation.
- Membrane deformation, rather than electrostatics alone, governs ion permeation.
Conclusions:
- Ion permeation is less sensitive to hydration and electrostatics than previously thought.
- Compensation between polar and nonpolar solvation effects within the membrane is crucial.
- Locally deformed bilayer interfaces explain why the dipole potential is not fully sensed, impacting predictions for various charged species and membrane processes.
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