Protein surface and core dynamics show concerted hydration-dependent activation

Area of Science:

• Biophysics
• Protein Dynamics
• Neutron Scattering

Background:

• Understanding protein dynamics is crucial for deciphering protein function.
• Internal and external protein environments may exhibit distinct dynamic behaviors.
• Nanosecond timescale dynamics are important for various biological processes.

Purpose of the Study:

• To compare the "inside" and "outside" protein dynamics on the nanosecond timescale.
• To investigate the influence of temperature and hydration on protein dynamics.
• To probe the behavior of leucine/valine methyl groups and lysine side chains.

Main Methods:

• Utilized neutron scattering techniques.
• Specifically labeled leucine/valine methyl groups and lysine side chains.
• Analyzed protein dynamics across varying temperatures and hydration levels.

Main Results:

• Observed surprisingly similar dynamics for both internal (leucine/valine) and external (lysine) labeled groups.
• Demonstrated that protein dynamics are similar as a function of temperature for both groups.
• Revealed that the buried hydrophobic core is sensitive to hydration and exhibits a dynamical transition.

Conclusions:

• Protein interior and exterior dynamics are more coupled than previously thought on the nanosecond timescale.
• Hydration plays a critical role in the dynamical behavior of the hydrophobic core.
• A distinct dynamical transition occurs in the protein core, influenced by hydration levels.