Instrumental resolution effects in neutron scattering studies of protein dynamics

Highlights: ► Resolution effects in neutron scattering measurements on protein are discussed. ► Three spectrometers of differing resolution were used. ► Fitting of spectra for the determination of EISF should use a flat background. ► MSD for dry and hydrated GFP shows resolution effects for the primary onsets. ► Hydration water shows resolution effects for the onset of translational motion. - Abstract: In this study, the dynamics of Green Fluorescent protein (GFP) are analyzed using three neutron scattering spectrometers. We focus on the effect of instrumental energy resolution in the analysis of the elastic incoherent structure factor (EISF) and mean square displacement (MSD). This topic still remains a source of controversy. Our data clearly demonstrate the presence of the resolution effect in the dynamic transition for hydrated protein and the onset of translational motions in hydration water consistent with previous results from quasielastic neutron scattering. The 190 K onset of motions in hydration water observed at ∼1 ns is also consistent with a Tg of hydration water below 190 K