Neutron frequency windows and the protein dynamical transition.

Area of Science:

• Biophysics
• Protein Dynamics
• Computational Biology

Background:

• Proteins exhibit dynamical transitions with temperature, often linked to their function.
• Observed protein dynamics depend on the interplay between relaxation processes and experimental/simulation timescales.
• Two models, 'equilibrium' and 'frequency window,' explain these transitions.

Purpose of the Study:

• To investigate the applicability of the 'frequency window' model to protein dynamics.
• To analyze temperature and timescale dependencies in protein motion.
• To compare simulation and experimental data for protein dynamics.

Main Methods:

• Molecular dynamics simulations of a small protein in cryosolution.
• Analysis of intermediate neutron scattering function and mean-square displacement ().
• Experimental neutron scattering on glutamate dehydrogenase in cryosolution.

Main Results:

• The 'frequency window' model successfully describes temperature and timescale effects on protein dynamics in simulations.
• This model also explains experimental neutron scattering data for glutamate dehydrogenase.
• temperature and energy-resolution dependencies are consistent with the frequency window model.

Conclusions:

• The 'frequency window' model is a significant factor in interpreting protein dynamics observed in simulations and experiments.
• While equilibrium effects also contribute, instrumental timescales play a crucial role.
• Understanding these dynamics is key to solvent-activated protein function and activity.