Effects of heavy water on protein dynamics studied by molecular dynamics simulation: Focusing on dynamical parameters obtained by quasi-elastic neutron scattering

Quasi-elastic neutron scattering (QENS) is a powerful technique to study protein dynamics. In general, QENS measurements are carried out in D2O solvent whereas functional studies of proteins are conducted in H2O solvent. Therefore, to link the QENS studies with the functional studies and then to understand the molecular basis of protein functions in detail, it is important to investigate the effects of solvent isotopic change on dynamical parameters obtained by QENS. For this purpose, in this study, MD simulations were carried out on hen egg white lysozyme, a well-folded and characterized protein, in H2O and in D2O. The dynamical parameters were extracted from the QENS spectra calculated from the MD trajectories. It was found that isotopic effects depend on energy resolutions and that at the energy resolutions that recent QENS studies often employ, the local dynamical behavior of proteins characterized in D2O more or less reflects that in H2O.