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Updated: Oct 5, 2025

Author Spotlight: Exploring Intrinsically Disordered Protein Dynamics Through NMR Relaxation Experiments
Published on: November 1, 2024
Dynamics of Cations around DNA and Protein as Revealed by 23Na Diffusion NMR Spectroscopy
Binhan Yu1, Karina G Bien1, Channing C Pletka1
1Department of Biochemistry and Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, Texas 77555-1068 United States.
Abstract:
Counterions are vital for the structure and function of biomolecules. However, the behavior of counterions remains elusive due to the difficulty in characterizing mobile ions. Here, we demonstrate that the dynamics of cations around biological macromolecules can be revealed by 23Na diffusion nuclear magnetic resonance (NMR) spectroscopy. NMR probe hardware capable of generating strong magnetic field gradients enables 23Na NMR-based diffusion measurements for Na+ ions in solutions of biological macromolecules and their complexes. The dynamic properties of Na+ ions interacting with the macromolecules can be investigated using apparent 23Na diffusion coefficients measured under various conditions. Our diffusion data clearly show that Na+ ions retain high mobility within the ion atmosphere around DNA. The 23Na diffusion NMR method also permits direct observation of the release of Na+ ions from nucleic acids upon protein-nucleic acid association. The entropy change due to the ion release can be estimated from the diffusion data.
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