Molecular dynamics simulations of DPPC bilayers using "LIME", a new coarse-grained model

Area of Science:

• Computational chemistry
• Biophysics
• Materials science

Background:

• Phospholipids are crucial components of cell membranes.
• Accurate modeling of lipid bilayers is essential for understanding membrane function.
• Existing models may lack efficiency or accuracy for large-scale simulations.

Purpose of the Study:

• To introduce LIME, a novel intermediate-resolution model for phospholipids.
• To enable efficient simulation of lipid bilayer formation and properties using discontinuous molecular dynamics (DMD).
• To validate the model against experimental data and known phase behaviors.

Main Methods:

• Developed an implicit-solvent model (LIME) using a multiscale approach.
• Derived geometric and energetic parameters from atomistic simulations of DPPC and water.
• Represented DPPC using 14 coarse-grained sites of 6 types.
• Performed DMD simulations to observe bilayer formation and phase transitions.

Main Results:

• Achieved defect-free bilayer formation in under 4 hours.
• The simulated bilayer accurately reproduced experimental structural properties (area per lipid, thickness, order parameters).
• Observed temperature-dependent phase transitions (liquid-crystalline to tilted gel) and transbilayer lipid movement.

Conclusions:

• LIME is an effective coarse-grained model for simulating phospholipid bilayers.
• DMD simulations with LIME provide a rapid and accurate method for studying membrane structure and dynamics.
• The model facilitates research into lipid self-assembly and phase behavior relevant to biological membranes.