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Updated: May 5, 2026

Practical Aspects of Sample Preparation and Setup of 1H R1ρ Relaxation Dispersion Experiments of RNA
Published on: July 9, 2021
Characterizing slow chemical exchange in nucleic acids by carbon CEST and low spin-lock field R(1ρ) NMR spectroscopy
Bo Zhao1, Alexandar L Hansen, Qi Zhang
1Department of Biochemistry and Biophysics and ‡Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599, United States.
Abstract:
Quantitative characterization of dynamic exchange between various conformational states provides essential insights into the molecular basis of many regulatory RNA functions. Here, we present an application of nucleic-acid-optimized carbon chemical exchange saturation transfer (CEST) and low spin-lock field R(1ρ) relaxation dispersion (RD) NMR experiments in characterizing slow chemical exchange in nucleic acids that is otherwise difficult if not impossible to be quantified by the ZZ-exchange NMR experiment. We demonstrated the application on a 47-nucleotide fluoride riboswitch in the ligand-free state, for which CEST and R(1ρ) RD profiles of base and sugar carbons revealed slow exchange dynamics involving a sparsely populated (p ~ 10%) and shortly lived (τ ~ 10 ms) NMR "invisible" state. The utility of CEST and low spin-lock field R(1ρ) RD experiments in studying slow exchange was further validated in characterizing an exchange as slow as ~60 s(-1).
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