How well do empirical molecular mechanics force fields model the cholesterol condensing effect?
J Sawdon1, T J Piggot1,2, J W Essex1
1School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, United Kingdom.
The Journal of Chemical Physics
|January 28, 2025
Summary
Accurate molecular dynamics simulations of cholesterol-containing membranes require capturing the cholesterol condensing effect. All-atom force fields, like CHARMM36 or Slipids, are recommended for precise simulations, as united-atom and coarse-grained models under-predict this critical phenomenon.
Area of Science:
- Membrane biophysics and molecular modeling.
- Computational chemistry and lipid dynamics.
Background:
- Cholesterol significantly influences membrane properties, affecting cellular biomechanics, raft formation, and disease.
- The cholesterol condensing effect, a reduction in membrane area due to non-ideal mixing, is vital for accurate simulations.
- Existing molecular dynamics force fields vary in their ability to capture this effect.
Purpose of the Study:
- To comparatively analyze cholesterol models across popular molecular dynamics force fields.
- To evaluate the accuracy of different force fields in simulating the cholesterol condensing effect.
- To identify optimal force fields for simulating cholesterol-membrane interactions.
Main Methods:
- Molecular dynamics simulations of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) membranes with varying cholesterol concentrations.
- Calculation of partial-molecular areas and condensing parameters for cholesterol and lipids.
- Comparison of simulation results with experimental data for validation across force fields: CHARMM36, Slipids, Lipid17, GROMOS 53A6L, GROMOS-CKP, MARTINI 2, MARTINI 3, and ELBA.
Main Results:
- All tested force fields showed some deviation from ideal mixing in cholesterol-DOPC membranes.
- Only all-atom force fields accurately captured the significant deviations observed in cholesterol-DMPC membranes.
- United-atom and coarse-grained models under-predicted the cholesterol condensing effect, leading to less accurate membrane property predictions.
Conclusions:
- All-atom force fields are essential for accurately simulating cholesterol-containing membranes.
- CHARMM36 and Slipids are recommended for precise molecular dynamics simulations of cholesterol-membrane interactions.
- Accurate simulation of the cholesterol condensing effect is critical for understanding membrane function and related diseases.
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