Coupled thermal fluctuations of proteins and protein hydration water on the picosecond timescale.

Alessandro Paciaroni (1) , Andrea Orecchini (2) , Elena Cornicchi (3) , Matteo Marconi (2) , Caterina Petrillo (4) , Francesco Sacchetti (5) , Michael Haertlein (6) , Martine Moulin (6)

1 Physics
2 Physics
3 UNIPG - Università degli Studi di Perugia = University of Perugia
4 physics
5 dipartimento di fisica
6 ILL - Institut Laue-Langevin

The mean square displacements (MSD) of a model protein, the Maltose Binding Protein, and its hydration water have been estimated by the elastic neutron scattering intensity measured on the time-of-flight spectrometer IN5. The availability of the protein in both fully deuterated and hydrogenated form allowed us to reliably separate the contribution of the solvent interacting with biomolecule from the one of the hydrated biomolecule. The thermal fluctuations of hydration water and protein activate in the same temperature range 200÷220K. This result supports a picture where the dynamical coupling between the biomolecule and the solvent is already effective in the picosecond timescale. A quantitative agreement of the MSD with the values from molecular dynamics simulations is found.

Mots clés: Physical Sciences

Alessandro Paciaroni, Andrea Orecchini, Elena Cornicchi, Matteo Marconi, Caterina Petrillo, et al.. Coupled thermal fluctuations of proteins and protein hydration water on the picosecond timescale.. Philosophical Magazine, 2008, 88 (33-35), pp.4071-4077. ⟨10.1080/14786430802464263⟩. ⟨hal-00513973⟩