The Role of Water in Dynamics of Biomacromolecules: A Mutual Interplay!

Abstract

We studied the dynamics of hydrated model RNA and protein using neutron and dielectric spectroscopy techniques combined with MD simulations. A comparison of our results with earlier data reveals that the dynamics of hydrated RNA is slower and varies more strongly with temperature than the dynamics of hydrated proteins. We demonstrate that a similar difference appears in the dynamics of hydration water for these biomolecules. In addition, we investigated the role of water and monovalent ion on the appearance of anharmonic motions in RNA by MD simulations of hydrated hammerhead RNA at various temperatures. While the dynamics of monovalent ions interacting with RNA infers a stronger coupling than that of water, it is found that the relaxation of water from the surface of RNA is sufficient for the increase in anharmonic motions above the dynamical transition temperature. The nature and temperature dependence of fast and slow hydrogen bond dynamics between proteins and RNA were found to be similar thus indicating that the dynamical transition of RNA and proteins are governed by relaxation of surface hydration water. Our results demonstrate that the dynamics of biological macromolecules and their hydration is a result of the mutual influence of biomolecules and their hydration water.