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Title: Nanosecond Relaxation Dynamics of Hydrated Proteins: Water versus protein contributions

Abstract

We have studied picosecond to nanosecond dynamics of hydrated protein powders using dielectric spectroscopy and molecular dynamics (MD) simulations. Our analysis of hydrogen-atom single particle dynamics from MD simulations focused on main ( main tens of picoseconds) and slow ( slow nanosecond) relaxation processes that were observed in dielectric spectra of similar hydrated protein samples. Traditionally, the interpretation of these processes observed in dielectric spectra has been ascribed to the relaxation behavior of hydration water tightly bounded to a protein and not to protein atoms. Detailed analysis of the MD simulations and comparison to dielectric data indicate that the observed relaxation process in the nanosecond time range of hydrated protein spectra is mainly due to protein atoms. The relaxation processes involve the entire structure of protein including atoms in the protein backbone, side chains, and turns. Both surface and buried protein atoms contribute to the slow processes; however, surface atoms demonstrate slightly faster relaxation dynamics. Analysis of the water molecule residence and dipolar relaxation correlation behavior indicates that the hydration water relaxes at much shorter time scales.

Authors:
 [1];  [2];  [3]
  1. University of Akron
  2. National Institute of Standards and Technology (NIST), Gaithersburg, MD
  3. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1015753
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Physical Chemistry B; Journal Volume: 115; Journal Issue: 19
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ATOMS; CHAINS; DIELECTRIC MATERIALS; HYDRATION; PROTEINS; RELAXATION; SPECTRA; SPECTROSCOPY; WATER

Citation Formats

Khodadadi, S, Curtis, J. E., and Sokolov, Alexei P. Nanosecond Relaxation Dynamics of Hydrated Proteins: Water versus protein contributions. United States: N. p., 2011. Web. doi:10.1021/jp1122213.
Khodadadi, S, Curtis, J. E., & Sokolov, Alexei P. Nanosecond Relaxation Dynamics of Hydrated Proteins: Water versus protein contributions. United States. doi:10.1021/jp1122213.
Khodadadi, S, Curtis, J. E., and Sokolov, Alexei P. 2011. "Nanosecond Relaxation Dynamics of Hydrated Proteins: Water versus protein contributions". United States. doi:10.1021/jp1122213.
@article{osti_1015753,
title = {Nanosecond Relaxation Dynamics of Hydrated Proteins: Water versus protein contributions},
author = {Khodadadi, S and Curtis, J. E. and Sokolov, Alexei P},
abstractNote = {We have studied picosecond to nanosecond dynamics of hydrated protein powders using dielectric spectroscopy and molecular dynamics (MD) simulations. Our analysis of hydrogen-atom single particle dynamics from MD simulations focused on main ( main tens of picoseconds) and slow ( slow nanosecond) relaxation processes that were observed in dielectric spectra of similar hydrated protein samples. Traditionally, the interpretation of these processes observed in dielectric spectra has been ascribed to the relaxation behavior of hydration water tightly bounded to a protein and not to protein atoms. Detailed analysis of the MD simulations and comparison to dielectric data indicate that the observed relaxation process in the nanosecond time range of hydrated protein spectra is mainly due to protein atoms. The relaxation processes involve the entire structure of protein including atoms in the protein backbone, side chains, and turns. Both surface and buried protein atoms contribute to the slow processes; however, surface atoms demonstrate slightly faster relaxation dynamics. Analysis of the water molecule residence and dipolar relaxation correlation behavior indicates that the hydration water relaxes at much shorter time scales.},
doi = {10.1021/jp1122213},
journal = {Journal of Physical Chemistry B},
number = 19,
volume = 115,
place = {United States},
year = 2011,
month = 1
}
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