Abstract
A unique aspect of NMR is its capacity to provide integrated insight into both the structure and intrinsic dynamics of biomolecules. Chemical exchange phenomena that often serve as probes of dynamic processes in biological macromolecules can be quantitatively investigated with chemical exchange saturation transfer (CEST) experiments. 2H-decoupling sidebands, however, always occur in the profiles of 13CHD2 13C-CEST experiments when using the simple CW (continuous wave) method, which may obscure the detection of minor dips of excited states. Traditionally, these sidebands are manually eliminated from the profiles before data analysis by removing experimental points in the range of 2H-decoupling field strength ±50 Hz away from the major dips of the ground state on either side of the dips. Unfortunately, this may also eliminate potential minor dips if they overlap with the decoupling sidebands. Here, we developed methods that use pseudo-continuous waves with variable RF amplitudes distributed onto ramps for 2H decoupling. The new methods were thoroughly validated on Bruker spectrometers at a range of fields (1H frequencies of 600, 700, and 850 MHz, and 1.1 GHz). By using these methods, we successfully removed the sidebands from the NMR profiles of 13CHD2 13C-CEST experiments.
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Data availability
The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.
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Acknowledgements
We thank Lewis E. Kay, Ph.D., for original pulse sequence, advice and discussion, Zhilian Xia for providing the 13CHD2-labeled sample and Nisha Badders, PhD, ELS, for scientific editing. This work is financially supported by USA NIH Grants R35 GM122462 to C.G.K. and by the Biomolecular NMR Center, St. Jude Children’s Research Hospital.
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Xia, Y., Yuwen, T., Liu, A. et al. Removal of 2H-decoupling sidebands in 13CHD2 13C-CEST profiles. J Biomol NMR 75, 133–142 (2021). https://doi.org/10.1007/s10858-021-00362-0
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DOI: https://doi.org/10.1007/s10858-021-00362-0