Dramatic Decrease in CEST Measurement Times Using Multi-Site Excitation

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Dramatic Decrease in CEST Measurement Times Using Multi-Site Excitation, ChemPhysChem 2018, 19, 1707-1710

 

Chemical exchange saturation transfer (CEST) has emerged as a powerful NMR approach for studies of sparsely populated, transiently formed (excited) states of both proteins and nucleic acids. A wide variety of CEST‐based experiments have recently been developed for biomolecular applications that amplify signals from 15N, 13C or 1H spin probes of excited states, bringing into view conformers that are recalcitrant to study using other biophysical approaches. In the CEST experiment a weak B1 field, typically between 10–50 Hz, is applied, one frequency at a time, so as to cover the frequency range of the resonances of interest (for example, between 105–135 ppm for amide 15N spins) and the intensities of peaks from the major conformational (ground) state are quantified.

 

 

In summary, we have presented a simple frequency‐selective based CEST scheme that builds on the DANTE sequence first proposed over 40 years ago. The approach is easy to implement and the results can be analyzed in a straightforward manner using software that is available upon request (https://github.com/gbouvignies/chemex). The method can be combined with NUS approaches resulting in further savings in measurement times, as has been recently described in the context of pseudo‐4D CEST applications. Even without NUS, the D‐CEST experiment offers very significant decreases in measurement times, by as much as an order of magnitude in certain applications, and as such it will be a powerful addition to the repertoire of experiments that probe biomolecular dynamics.

 

Pour plus d'informations, n'hésitez pas à consulter le communiqué de presse : Observer la dynamique des biomolécules en un temps record ! 

 

 

Résumé: 

ChemPhysChem 2018, 19, 1707-1710

 

Chemical exchange saturation transfer (CEST) has recently evolved into a powerful approach for studying sparsely populated, “invisible” protein states in slow exchange with a major, visible conformer. Central to the technique is the use of a weak, highly selective radio‐frequency field that is applied at different frequency offsets in successive experiments, “searching” for minor state resonances. The recording of CEST profiles with enough points to ensure coverage of the entire spectrum at sufficient resolution can be time‐consuming, especially for applications that require high static magnetic fields or when small chemical shift differences between exchanging states must be quantified. Here, we show – with applications involving 15N CEST – that the process can be significantly accelerated by using a multi‐frequency irradiation scheme, leading in some applications to an order of magnitude savings in measurement time.

 

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Dramatic Decrease in CEST Measurement Times Using Multi-Site Excitation

 

Tairan Yuwena, Lewis E. Kaya,b, and Guillaume Bouvigniesc

 

[a] Departments of Molecular Genetics, Biochemistry and Chemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada

[b] Hospital for Sick Children, Program in Molecular Medicine, 555 University Avenue, Toronto, Ontario M5G 1X8, Canada

[c] Laboratoire des biomolécules, LBM, Département de chimie, École normale supérieure, PSL University, Sorbonne Université, CNRS, 75005 Paris, France

 

ChemPhysChem 2018, 19, 1707-1710

 

DOI: 10.1002/cphc.201800249