Protein interactions and dynamics probed by quantum chemistry, computer simulations and neutron experiments

We review some recent experiments and calculations on aspects of the structure and dynamics of proteins and related systems. The use of quantum chemical techniques to determine geometries and energies of supramolecular complexes of biological interest is illustrated, and the concomitant development of empirical energy functions for use in protein simulations outlined. We describe how simulations of crystalline peptides and amino-acids using an empirical force field can be combined with appropriate coherent and incoherent inelastic neutron scattering experiments to elucidate the characteristics of lattice vibrations and diffusive atomic motions in the crystals. The application of molecular dynamics simulations to the interpretation of incoherent neutron scattering experiments on proteins is examined and the resulting ideas on the general characteristics of protein motion discussed in terms of their functional implications.