Mechanical properties of lipid bilayers from molecular dynamics simulation

• Mechanical properties of 12 different bilayers are evaluated from simulation.
• The CHARMM 36 force field yields excellent area and compressibility.
• The relation of surface area and NMR order parameters does not fit simple models.
• Bending constants equal those from flicker experiments, but not others.
• Spontaneous curvatures of leaflets in bilayers are 30% lower than in hexagonal phases.

Lipid areas (Aℓ), bilayer area compressibilities (KA), bilayer bending constants (KC), and monolayer spontaneous curvatures (c0) from simulations using the CHARMM36 force field are reported for 12 representative homogenous lipid bilayers. Aℓ (or their surrogate, the average deuterium order parameter in the “plateau region” of the chain) agree very well with experiment, as do the KA. Simulated KC are in near quantitative agreement with vesicle flicker experiments, but are somewhat larger than KC from X-ray, pipette aspiration, and neutron spin echo for saturated lipids. Spontaneous curvatures of bilayer leaflets from the simulations are approximately 30% smaller than experimental values of monolayers in the inverse hexagonal phase.