Refined OPLS all-atom force field for saturated phosphatidylcholine bilayers at full hydration

Area of Science:

• Computational chemistry
• Molecular dynamics simulations
• Biophysics

Background:

• Phosphatidylcholines (PCs) are crucial lipids, but lack parameters in the Optimized Parameters for Liquid Simulations all-atom (OPLS-AA) force field.
• Dipalmitoyl-phosphatidylcholine (DPPC) is a well-studied and abundant phospholipid, essential for validating new force field parameters.

Purpose of the Study:

• To parametrize dipalmitoyl-phosphatidylcholine (DPPC) within the OPLS-AA force field.
• To derive accurate bonding, nonbonding, and partial atomic charge parameters for DPPC.
• To validate the generated parameters against experimental data for DPPC lipid bilayers.

Main Methods:

• Hartree-Fock (HF), Møller-Plesset perturbation theory (MP2), and density functional theory (DFT) were used for parameter derivation.
• The polarizable continuum model (PCM) was employed to simulate a polar environment.
• Van der Waals parameters for acyl chains were adjusted.
• Six distinct parameter sets were generated and tested on a DPPC bilayer.

Main Results:

• Only one of the six generated parameter sets successfully reproduced experimental data for the DPPC lipid bilayer.
• The optimal parameter set was derived from MP2 calculations performed in an implicit polar environment (PCM).

Conclusions:

• A validated OPLS-AA force field parameter set for DPPC has been successfully developed.
• This new parameter set enables accurate molecular dynamics simulations of DPPC-containing systems.
• The findings contribute to improved computational modeling of lipid bilayers and biological membranes.