United-atom acyl chains for CHARMM phospholipids.
In all-atom simulations of lipid membranes, explicit hydrogen atoms contained in the hydrocarbon region are described by a large number of degrees of freedom, although they convey only limited physical information. We propose an implicit-hydrogen model for saturated and monounsaturated acyl chains, aimed at complementing the all-atom CHARMM27 model for phospholipid headgroups. Torsional potentials and nonbonded parameters were fitted to reproduce experimental data and free energy surfaces of all-atom model systems. Comparative simulations of fluid-phase POPC bilayers were performed using the all-hydrogen force field and the present model. The hybrid model accelerates a typical bilayer simulation by about 50% while sacrificing a minimal amount of detail with respect to the fully atomistic description. In addition, the united-atom description is energetically compatible with all-atom CHARMM models, making it suitable for simulations of complex membrane systems.
Hénin
Jérôme
J
Center for Molecular Modeling, Department of Chemistry, University of Pennsylvania, 231 S. 34th Street, Philadelphia, PA 19104-6323, USA. jhenin@cmm.chem.upenn.edu
Shinoda
Wataru
W
Klein
Michael L
ML
D008051:Lipid Bilayers; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D010743:Phospholipids / Q000737:chemistry*
D008051:Lipid Bilayers; D010743:Phospholipids