Hydration-dependent dynamic crossover phenomenon in protein hydration water.
The characteristic relaxation time τ of protein hydration water exhibits a strong hydration level h dependence. The dynamic crossover is observed when h is higher than the monolayer hydration level hc=0.2-0.25 and becomes more visible as h increases. When h is lower than hc, τ only exhibits Arrhenius behavior in the measured temperature range. The activation energy of the Arrhenius behavior is insensitive to h, indicating a local-like motion. Moreover, the h dependence of the crossover temperature shows that the protein dynamic transition is not directly or solely induced by the dynamic crossover in the hydration water.
Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Zhe
Z
Wang
Department of Chemistry and CSGI, University of Florence, Sesto Fiorentino, Florence I-50019, Italy.
Emiliano
E
Fratini
Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Mingda
M
Li
Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Peisi
P
Le
Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
Eugene
E
Mamontov
Department of Chemistry and CSGI, University of Florence, Sesto Fiorentino, Florence I-50019, Italy.
Piero
P
Baglioni
Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Sow-Hsin
SH
Chen
D006860:Hydrogen Bonding; D008958:Models, Molecular; D033363:Neutron Diffraction; D011506:Proteins / Q000737:chemistry*; D013696:Temperature; D014867:Water / Q000737:chemistry*
D011506:Proteins; D014867:Water