title: Atomistic details of protein dynamics and the role of hydration water.
abstract: The importance of protein dynamics for their biological activity is now well recognized. Different experimental and computational techniques have been employed to study protein dynamics, hierarchy of different processes and the coupling between protein and hydration water dynamics. Yet, understanding the atomistic details of protein dynamics and the role of hydration water remains rather limited.
  
  
  
  Based on overview of neutron scattering, molecular dynamic simulations, NMR and dielectric spectroscopy results we present a general picture of protein dynamics covering time scales from faster than ps to microseconds and the influence of hydration water on different relaxation processes.
  
  
  
  Internal protein dynamics spread over a wide time range from faster than picosecond to longer than microseconds. We suggest that the structural relaxation in hydrated proteins appears on the microsecond time scale, while faster processes present mostly motion of side groups and some domains. Hydration water plays a crucial role in protein dynamics on all time scales. It controls the coupled protein-hydration water relaxation on 10-100ps time scale. This process defines the friction for slower protein dynamics. Analysis suggests that changes in amount of hydration water affect not only general friction, but also influence significantly the protein's energy landscape.
  
  
  
  The proposed atomistic picture of protein dynamics provides deeper understanding of various relaxation processes and their hierarchy, similarity and differences between various biological macromolecules, including proteins, DNA and RNA. This article is part of a Special Issue entitled "Science for Life" Guest Editor: Dr. Austen Angell, Dr. Salvatore Magazù and Dr. Federica Migliardo".
authors.affiliation: Faculty of Applied Sciences, Delft University of Technology, Delft, The Netherlands; Delft Project management B.V., Delft University of Technology, Delft, The Netherlands.
authors.forename: Sheila
authors.initials: S
authors.lastname: Khodadadi
authors.affiliation: Joint Institute for Neutron Sciences, University of Tennessee, Knoxville, TN, USA. Electronic address: sokolov@utk.edu.
authors.forename: Alexei P
authors.initials: AP
authors.lastname: Sokolov
mesh_terms: D056004:Molecular Dynamics Simulation; D009113:Muramidase / Q000737:chemistry*; D033363:Neutron Diffraction; D013057:Spectrum Analysis; D013816:Thermodynamics; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water; D009113:Muramidase
keywords: Dielectric spectroscopy; Energy landscape; Hydration water; MD simulation; Neutron scattering; Protein dynamics