Monitoring conformational dynamics with solid-state R 1rho experiments.

Area of Science:

• Solid-state Nuclear Magnetic Resonance (NMR) spectroscopy
• Chemical Physics
• Biophysics

Background:

• Conformational dynamics are crucial for molecular function.
• Observing slow-to-intermediate timescale dynamics in solids remains challenging.
• Current methods may lack site-specificity or sensitivity.

Purpose of the Study:

• To present a novel application of solid-state rotating frame (R(1rho)) relaxation experiments.
• To demonstrate the ability of R(1rho) relaxation to monitor conformational dynamics.
• To establish a new site-specific probe for studying molecular motion.

Main Methods:

• Utilized solid-state rotating frame (R(1rho)) relaxation experiments.
• Studied dimethyl sulfone (DMS) as a model compound.
• Performed control experiments with deuterated DMS (d(6)-DMS) and alanine.

Main Results:

• R(1rho) relaxation effectively monitors conformational exchange processes.
• The observed relaxation is attributed to chemical shift anisotropy (CSA) tensor reorientation during chemical exchange.
• Control experiments confirmed that the technique is sensitive to CSA tensor reorientation, not dipolar interactions or methyl group rotation.

Conclusions:

• Solid-state R(1rho) relaxation is a viable method for observing conformational dynamics.
• This technique provides a new way to probe slow-to-intermediate timescale molecular motions.
• The method holds potential for site-specific studies of protein dynamics.