Temperature dependence of the internal dynamics of a protein in an aqueous solvent: Decoupling from the solvent viscosity

E. Mamontov, H. O'Neill, Q. Zhang, S. M. Chathoth

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

We have recently observed decoupling of the dynamics of a protein from its aqueous solvent [Chu et al., JPCL 3 (2012) 380]; here we report the more detailed studies. We analyzed quasielastic neutron scattering data from a 40 mg/ml solution of lysozyme in (D2O)8(LiCl) and (H 2O)8(LiCl). The internal dynamics of lysozyme exhibited super-Arrhenius temperature dependence with no crossover to a different regime down to at least 200 K. The decoupling of the internal protein dynamics from the viscosity of its aqueous solvent is evident. The temperature dependence of the protein dynamics indicates an apparent dynamic arrest at a temperature above 190 K, whereas the glass transition temperature for the solvent is around 135-140 K. The internal dynamics of the solvated protein is coupled to the dynamics of its hydration shell, not of the bulk solvent, which is qualitatively altered by the salt to defer the dynamic arrest to 135-140 K.

Original languageEnglish
Pages (from-to)12-19
Number of pages8
JournalChemical Physics
Volume424
DOIs
StatePublished - 2013

Funding

The neutron scattering experiments at Oak Ridge National Laboratory’s (ORNL) Spallation Neutron Source were supported by the Scientific User Facilities Division, Office of Basic Energy Sciences, US Department of Energy (DOE). The authors acknowledge ORNL’s Center for Structural Molecular Biology (Project ERKP291) supported by the Office of Biological and Environmental Research, US DOE. ORNL is managed by UTBattelle, LLC, for the US DOE under Contract No. DE-AC05-00OR22725.

Keywords

  • Dynamics
  • Neutron scattering
  • Protein
  • Solution
  • Water

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