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Updated: Mar 12, 2026
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Paramagnetic Relaxation Enhancement for Detecting and Characterizing Self-Associations of Intrinsically Disordered Proteins
Published on: September 23, 2021
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Accelerating proton spin diffusion in perdeuterated proteins at 100 kHz MAS
Johannes J Wittmann1, Vipin Agarwal1,2, Johannes Hellwagner1
1Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, 8093, Zurich, Switzerland.
Journal of Biomolecular NMR
|November 3, 2016
Summary
Fast magic-angle spinning improves NMR but hinders proton-spin diffusion. New experiments like reverse MIRROR offer broadband spin diffusion, enabling better structural distance restraints by compensating for chemical-shift differences.
Area of Science:
- Solid-state Nuclear Magnetic Resonance (NMR) Spectroscopy
- Biophysical Chemistry
- Structural Biology
Background:
- Fast magic-angle spinning (MAS) in solid-state NMR enhances spectral resolution but complicates long-range proton-proton polarization transfer.
- Proton-spin diffusion efficiency is highly sensitive to chemical-shift offsets, limiting its utility in fast MAS regimes.
Purpose of the Study:
- To quantify the impact of chemical-shift differences on proton spin diffusion under fast MAS conditions.
- To compare rotating-frame spin diffusion with a novel reverse amplitude-modulated MIRROR experiment for improved chemical-shift compensation.
- To evaluate the suitability of these methods for determining structural distance restraints.
Main Methods:
- Utilized 100% deuterated, ¹³C, and ¹⁵N-labeled ubiquitin as a model system.
- Implemented and compared rotating-frame spin diffusion and the reverse amplitude-modulated MIRROR experiment.
- Employed tailored radiofrequency (rf) irradiation schemes to control recoupled chemical shifts and drive spin diffusion.
Main Results:
- Demonstrated that fast MAS significantly impacts spin-diffusion efficiency and its dependence on chemical-shift offset.
- Found rotating-frame spin diffusion to be limited by fast spin relaxation in the rotating frame.
- Showcased the reverse MIRROR experiment as a promising technique for broadband spin diffusion with improved chemical-shift compensation.
- Identified longitudinal relaxation time as a key factor for signal-to-noise ratio in the reverse MIRROR experiment.
Conclusions:
- The reverse MIRROR experiment offers an effective strategy for broadband spin diffusion, overcoming limitations of fast MAS.
- This method provides enhanced control over chemical-shift recoupling, making it valuable for obtaining structurally relevant distance restraints.
- The reverse MIRROR experiment holds significant potential for structural biology applications requiring precise distance measurements.
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