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Updated: Jan 5, 2026
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15N CPMG Relaxation Dispersion for the Investigation of Protein Conformational Dynamics on the µs-ms Timescale
Published on: April 19, 2021
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Revisiting 1HN CPMG relaxation dispersion experiments: a simple modification can eliminate large artifacts
Tairan Yuwen1, Lewis E Kay2,3
1Departments of Molecular Genetics, Biochemistry and Chemistry, University of Toronto, Toronto, ON, M5S 1A8, Canada.
Journal of Biomolecular NMR
|October 25, 2019
Summary
This study introduces an improved Carr-Purcell-Meiboom-Gill (CPMG) experiment for fully protonated protein samples. The new method overcomes artifacts, enabling accurate measurement of millisecond-timescale biomolecular dynamics using 1H spins.
Area of Science:
- Biophysics
- Structural Biology
- Nuclear Magnetic Resonance (NMR) Spectroscopy
Background:
- Carr-Purcell-Meiboom-Gill (CPMG) relaxation dispersion experiments are vital for studying millisecond-timescale biomolecular dynamics.
- Standard CPMG experiments often use 15N spins, while 1H-based experiments on fully protonated samples are challenging due to homonuclear scalar couplings causing artifacts.
- These artifacts, arising from magnetization transfer between coupled spins, hinder accurate data acquisition in 1H-based studies.
Purpose of the Study:
- To analyze the artifacts in a previously used 1HN CPMG experiment.
- To present a novel, significantly improved 1HN CPMG pulse sequence for enhanced data quality.
- To demonstrate the utility of the new sequence for measuring biomolecular dynamics in fully protonated systems.
Main Methods:
- Examination of a specific 1HN CPMG experiment incorporating CPMG pulse trains and an amide-selective pulse.
- Explanation of the origins of artifacts in the original experimental scheme.
- Development and application of a new, artifact-reducing pulse sequence for 1HN CPMG experiments.
Main Results:
- The origin of artifacts in the original 1HN CPMG scheme was identified and explained.
- A new, improved 1HN CPMG pulse sequence was developed and presented.
- The new experiment successfully generated flat 1HN dispersion profiles in a protein lacking expected dynamics.
- High-quality dispersion profiles were obtained for a T4 lysozyme mutant undergoing conformational exchange, validating the new method.
Conclusions:
- The developed 1HN CPMG experiment effectively mitigates artifacts in fully protonated protein samples.
- This advancement allows for high-quality measurement of millisecond-timescale dynamics using 1H spins, expanding the applicability of CPMG experiments.
- The improved sequence provides a robust tool for structural biology and biophysics research involving complex, fully protonated biomolecules.
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