Lipid Head Group Parameterization for GROMOS 54A8: A Consistent Approach with Protein Force Field Description

Area of Science:

• Biophysics
• Computational Biology
• Materials Science

Background:

• Cell membranes utilize diverse lipids for signaling and transport, increasing system complexity.
• Molecular dynamics (MD) simulations offer atomistic detail for studying model membranes and protein interactions.
• Accurate force field parameters are essential for reliable MD simulations of membrane behavior.

Purpose of the Study:

• To develop and validate new lipid head group parameters for the GROMOS 54A8 force field.
• To ensure consistency between lipid and protein parameterization for integrated simulations.
• To enhance the accuracy of MD simulations for phosphocholine model bilayers.

Main Methods:

• Developed new lipid head group parameters using recent chemical moiety parametrizations.
• Generated a new set of partial charges for lipids, consistent with protein parameterization.
• Performed 500 ns MD simulations on five large phosphocholine model bilayers (4x larger patches).

Main Results:

• Achieved good reproduction of experimental data (area per lipid, deuterium order parameters).
• Accurately described the liquid crystal to gel-phase transition.
• Demonstrated more realistic head group orientational behavior compared to previous parameterizations.

Conclusions:

• The new GROMOS 54A8 lipid parameters provide a more accurate representation of membrane behavior.
• Enhanced head group orientation improves the simulation of interactions with polar molecules.
• Validated by improved realism in antimicrobial peptide (lactoferricin) binding simulations to different membrane types.