Molecular dynamics
(MD) simulations are widely used to monitor
time-resolved motions of biomacromolecules, although it often remains
unknown how closely the conformational dynamics correspond to those
occurring in real life. Here, we used a large set of open-access MD
trajectories of phosphatidylcholine (PC) lipid bilayers to benchmark
the conformational dynamics in several contemporary MD models (force
fields) against nuclear magnetic resonance (NMR) data available in
the literature: effective correlation times and spin–lattice
relaxation rates. We found none of the tested MD models to fully reproduce
the conformational dynamics. That said, the dynamics in CHARMM36 and
Slipids are more realistic than in the Amber Lipid14, OPLS-based MacRog,
and GROMOS-based Berger force fields, whose sampling of the glycerol
backbone conformations is too slow. The performance of CHARMM36 persists
when cholesterol is added to the bilayer, and when the hydration level
is reduced. However, for conformational dynamics of the PC headgroup,
both with and without cholesterol, Slipids provides the most realistic
description because CHARMM36 overestimates the relative weight of
∼1 ns processes in the headgroup dynamics. We stress that not
a single new simulation was run for the present work. This demonstrates
the worth of open-access MD trajectory databanks for the indispensable
step of any serious MD study: benchmarking the available force fields.
We believe this proof of principle will inspire other novel applications
of MD trajectory databanks and thus aid in developing biomolecular
MD simulations into a true computational microscope—not only
for lipid membranes but for all biomacromolecular systems.