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NMR 15N Relaxation Experiments for the Investigation of Picosecond to Nanoseconds Structural Dynamics of Proteins
Published on: November 1, 2024
Protein linewidth and solvent dynamics in frozen solution NMR.
Ansgar B Siemer1, Kuo-Ying Huang, Ann E McDermott
1Department of Chemistry, Columbia University, New York, New York, United States of America. asiemer@usc.edu
Plos One
|October 19, 2012
Summary
Solid-state NMR studies reveal that ¹³C protein linewidths in frozen solutions worsen at lower temperatures. Glycerol-water mixtures offer narrower lines than pure water, improving high-resolution structural biology potential.
Area of Science:
- Structural Biology
- Biophysical Chemistry
- Nuclear Magnetic Resonance (NMR) Spectroscopy
Background:
- Solid-state NMR of proteins in frozen solutions is valuable for structural biology, especially with dynamic nuclear polarization (DNP) enhancement.
- A key challenge is linewidth broadening at low temperatures, hindering high-resolution analysis.
Purpose of the Study:
- To investigate the impact of solvent composition (water vs. glycerol-water) and temperature on protein linewidths in frozen solutions.
- To understand the relationship between solvent dynamics and NMR linewidth broadening.
Main Methods:
- Recorded ¹H, ²H, and ¹³C solid-state NMR spectra of ubiquitin in frozen water and glycerol-water solutions.
- Varied sample temperatures to observe effects on spectral linewidths.
- Characterized water dynamics using ¹H and ²H NMR.
Main Results:
- ¹³C protein linewidths generally increased as temperature decreased.
- Line broadening was inhomogeneous and unaffected by proton decoupling.
- Pure water showed abrupt broadening upon freezing, unlike glycerol-water mixtures.
- Glycerol-water mixtures resulted in narrower NMR lines compared to pure water at equivalent temperatures.
- ¹³C line broadening was largely independent of the arrest of isotropic water motion.
Conclusions:
- Solvent composition significantly influences protein linewidths in frozen solutions for solid-state NMR.
- Glycerol-water mixtures provide a more favorable environment for high-resolution NMR studies of frozen proteins compared to pure water.
- The observed line broadening is primarily related to solvent freezing and temperature, rather than solely the arrest of water molecule dynamics.
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