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CEST experiments for ¹³C, ¹⁵N-labeled samples

Files

You can get the example files from the GitHub ChemEx page: ¹⁵N CEST and ¹³C CEST.

This example demonstrates the analysis of CEST datasets measured for uniformly ¹³C, ¹⁵N-labeled samples, which include both ¹³C (cest_13c) and ¹⁵N (cest_15n) CEST experiments. In uniformly ¹³C, ¹⁵N-labeled samples, due to extensive ¹JCC and ¹JCN coupling network, the data analysis becomes more complicated compared with the case when such couplings are absent. If ¹JCC or ¹JCN are not taken into account properly it is difficult to obtain proper fitting results, especially when the scalar couplings have a relatively large size.

ChemEx can take into account ¹JCC and ¹JCN couplings for analyzing ¹³C or ¹⁵N CEST datasets. Since the number and size of ¹JCC and ¹JCN for each specific ¹³C site depends on both the residue and atom name, such information should be provided in the name of each data profile to be taken into account properly, which is especially important for side-chain study with ¹³C CEST.1

info

  1. label key should be set properly in experiment files to indicate whether the sample is uniformly ¹³C-labeled or not.

  2. For both experiments it is implicitly assumed that the sample under study is always ¹⁵N-labeled, therefore it is not necessary to include "15N" in the list associated to the label key.

Footnotes​

  1. P. Vallurupalli, G. Bouvignies, L. E. Kay. A Computational Study of the Effects of ¹³C–¹³C Scalar Couplings on ¹³C CEST NMR Spectra: Towards Studies on a Uniformly ¹³C-Labeled Protein. ChemBioChem 14, 1709-1713 (2014). https://doi.org/10.1002/cbic.201300230 ↩