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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
Slow diffusion of macromolecular assemblies by a new pulsed field gradient NMR method
Fabien Ferrage1, Manuela Zoonens, Dror E Warschawski
1Département de Chimie, associé au CNRS, Ecole Normale Supérieure, 24 rue Lhomond, F-75231 Paris Cedex 05, France.
Journal of the American Chemical Society
|February 27, 2003
Summary
A novel pulsed field gradient NMR method enables precise measurement of diffusion coefficients for large molecules like protein complexes. This technique enhances diffusion interval duration, allowing analysis of macromolecular assemblies previously challenging to study.
Area of Science:
- Biophysical Chemistry
- Nuclear Magnetic Resonance (NMR) Spectroscopy
- Membrane Protein Characterization
Background:
- Integral membrane proteins and their complexes are crucial for cellular functions but challenging to study due to their hydrophobic nature.
- Accurate measurement of translational diffusion coefficients is essential for understanding molecular interactions and assembly dynamics.
- Existing NMR methods often have limitations in measuring diffusion for large or slow-moving macromolecular assemblies.
Purpose of the Study:
- To develop and validate a novel pulsed field gradient NMR method for measuring translational diffusion coefficients.
- To enable the study of macromolecular assemblies with diffusion coefficients below 10(-10) m(2) s(-1).
- To apply the method to integral membrane protein complexes and other large biomolecules.
Main Methods:
- Utilized a novel pulsed field gradient NMR approach storing molecular localization information in long spin-lattice relaxation time isotopes.
- Extended the diffusion interval duration by approximately one order of magnitude compared to standard methods.
- Applied the technique to a bacterial outer membrane protein A (tOmpA) complex and recombinant human tRNA(3)(Lys).
Main Results:
- Successfully measured the diffusion coefficient of the tOmpA/C(8)E(4) complex (approx. 45 kDa) as D = (4.99 ± 0.07) x 10(-11) m(2) s(-1).
- Determined the diffusion coefficient for human tRNA(3)(Lys) (approx. 24 kDa) as D = (1.05 ± 0.015) x 10(-10) m(2) s(-1).
- Results were consistent with complementary biophysical techniques like size exclusion chromatography and ultracentrifugation.
Conclusions:
- The novel NMR method is effective for measuring diffusion coefficients of macromolecular assemblies, including integral membrane protein complexes.
- This technique overcomes limitations of standard NMR methods for studying slow-diffusing molecules (>25 kDa).
- The developed method offers a valuable tool for biophysical characterization of large biomolecular systems in solution.
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