  The effects of static electric field on the dynamics of lysozyme and its
hydration water have been investigated by means of incoherent quasi-elastic
neutron scattering (QENS). Measurements were performed on lysozyme samples,
hydrated respectively with heavy water (D2O) to capture the protein dynamics,
and with light water (H2O), to probe the dynamics of the hydration shell, in
the temperature range from 210 $<$ T $<$ 260 K. The hydration fraction in both
cases was about $\sim$ 0.38 gram of water per gram of dry protein. The field
strengths investigated were respectively 0 kV/mm and 2 kV/mm (2 10$^6$ V/m) for
the protein hydrated with D2O and 0 kV and 1 kV/mm for the H2O hydrated
counterpart. While the overall internal protons dynamics of the protein appears
to be unaffected by the application of electric field up to 2 kV/mm, likely due
to the stronger intra-molecular interactions, there is also no appreciable
quantitative enhancement of the diffusive dynamics of the hydration water, as
would be anticipated based on our recent observations in water confined in
silica pores under field values of 2.5 kV/mm. This may be due to the difference
in surface interactions between water and the two adsorption hosts (silica and
protein), or to the existence of a critical threshold field value Ec $\sim$ 2-3
kV/mm for increased molecular diffusion, for which electrical breakdown is a
limitation for our sample.
