Structure and dynamics of bacteriorhodopsin. Comparison of simulation and experiment.

Global features of the structure and dynamics of bacteriorhodopsin are investigated using molecular modelling, dynamical simulations and neutron scattering experiments. The simulations are performed on a model system consisting of one protein molecule plus intrinsic water molecules. The simulation-derived structure is compared with neutron diffraction data on the location of water and with the available electron microscopy structure of highest resolution. The simulated water geometry is in good accord with the neutron data. The protein structure deviates slightly but significantly from the experiment. The low-frequency vibrational frequency distribution of a low-hydration purple membrane is derived from inelastic neutron scattering data and compared with the corresponding simulation-derived quantity.