%0 Journal Article
%A Kämpf, Kerstin
%A Demuth, Dominik
%A Zamponi, Michaela
%A Wuttke, Joachim
%A Vogel, Michael
%T Quasielastic neutron scattering studies on couplings of protein and water dynamics in hydrated elastin
%J The journal of chemical physics
%V 152
%N 24
%@ 1089-7690
%C Melville, NY
%I American Institute of Physics
%M FZJ-2020-02445
%P 245101 -
%D 2020
%X erforming quasielastic neutron scattering measurements and analyzing both elastic and quasielasic contributions, we study protein and water dynamics of hydrated elastin. At low temperatures, hydration-independent methyl group rotation dominates the findings. It is characterized by a Gaussian distribution of activation energies centered at about Em = 0.17 eV. At ∼195 K, coupled protein–water motion sets in. The hydration water shows diffusive motion, which is described by a Gaussian distribution of activation energies with Em = 0.57 eV. This Arrhenius behavior of water diffusion is consistent with previous results for water reorientation, but at variance with a fragile-to-strong crossover at ∼225 K. The hydration-related elastin backbone motion is localized and can be attributed to the cage rattling motion. We speculate that its onset at ∼195 K is related to a secondary glass transition, which occurs when a β relaxation of the protein has a correlation time of τβ ∼ 100 s. Moreover, we show that its temperature-dependent amplitude has a crossover at the regular glass transition Tg = 320 K of hydrated elastin, where the α relaxation of the protein obeys τα ∼ 100 s. By contrast, we do not observe a protein dynamical transition when water dynamics enters the experimental time window at ∼240 K.
%F PUB:(DE-HGF)16
%9 Journal Article
%$ pmid:32610976
%U <Go to ISI:>//WOS:000546996600001
%R 10.1063/5.0011107
%U https://juser.fz-juelich.de/record/877757