A quantitative coarse-grain model for lipid bilayers.

Area of Science:

• Biophysics
• Computational Chemistry
• Materials Science

Background:

• Phospholipid bilayers are fundamental components of cell membranes.
• Accurate modeling of biomembranes is crucial for understanding cellular processes.
• Existing coarse-grain methods have limitations in capturing key physical features.

Purpose of the Study:

• To develop a novel, computationally efficient particle-based model for hydrated phospholipid bilayers.
• To quantitatively predict major physical characteristics of fluid-phase biomembranes.
• To introduce advancements in electrostatic and water modeling within a coarse-grain framework.

Main Methods:

• Developed a simplified particle-based computer model incorporating explicit charges, dipoles, soft sticky dipole model for water, and anisotropic Gay-Berne potential for hydrocarbon tails.
• Employed rigid-body molecular dynamics for simulations.
• Achieved a 2-order of magnitude reduction in computational resources compared to atomic-level methods.

Main Results:

• The model quantitatively reproduces experimental observables including electron density, compressibility moduli, dipole potential, lipid diffusion, and water permeability.
• Calculated lateral pressure profile and elastic curvature constants consistent with experimental and atomic-level data.
• Several results, including elastic curvature constants, were obtained for the first time using a coarse-grain method.

Conclusions:

• The developed simplified particle-based model offers a highly efficient and accurate approach for simulating hydrated phospholipid bilayers.
• The model successfully predicts key physical and elastic properties of biomembranes.
• Compatibility with atomic-level force fields enables multiscale simulations for complex biological systems.