1. Quantitative analysis of the slow exchange process by 19 F NMR in the presence of scalar and dipolar couplings: applications to the ribose 2'- 19 F probe in nucleic acids.
- Author
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Toyama Y and Shimada I
- Abstract
Solution NMR spectroscopy is a particularly powerful technique for characterizing the functional dynamics of biomolecules, which is typically achieved through the quantitative characterization of chemical exchange processes via the measurement of spin relaxation rates. In addition to the conventional nuclei such as
15 N and13 C, which are abundant in biomolecules, fluorine-19 (19 F) has recently garnered attention and is being widely used as a site-specific spin probe. While19 F offers the advantages of high sensitivity and low background, it can be susceptible to artifacts in quantitative relaxation analyses due to a multitude of dipolar and scalar coupling interactions with nearby1 H spins. In this study, we focused on the ribose 2'-19 F spin probe in nucleic acids and investigated the effects of1 H-19 F spin interactions on the quantitative characterization of slow exchange processes on the millisecond time scale. We demonstrated that the1 H-19 F dipolar coupling can significantly affect the interpretation of19 F chemical exchange saturation transfer (CEST) experiments when1 H decoupling is applied, while the1 H-19 F interactions have a lesser impact on Carr-Purcell-Meiboom-Gill relaxation dispersion applications. We also proposed a modified CEST scheme to alleviate these artifacts along with experimental verifications on self-complementary RNA systems. The theoretical framework presented in this study can be widely applied to various19 F spin systems where1 H-19 F interactions are operative, further expanding the utility of19 F relaxation-based NMR experiments., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)- Published
- 2024
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