A simple double quantum coherence ESR sequence that minimizes nuclear modulations in Cu(2+)-ion based distance measurements.
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Abstract | :
Double quantum coherence (DQC) ESR is a sensitive method to measure magnetic dipolar interactions between spin labels. However, the DQC experiment on Cu(2+) centers presents a challenge at X-band. The Cu(2+) centers are usually coordinated to histidine residues in proteins. The electron-nuclear interaction between the Cu(2+) ion and the remote nitrogen in the imidazole ring can interfere with the electron-electron dipolar interaction. Herein, we report on a modified DQC experiment that has the advantage of reduced contributions from electron-nuclear interactions, which enhances the resolution of the DQC signal to the electron-electron dipolar modulations. The modified pulse-sequence is verified on Cu(2+)-NO system in a polyalanine-based peptide and on a coupled Cu(2+) system in a polyproline-based peptide. The modified DQC data were compared with the DEER data and good agreement was found. |
Year of Publication | :
2015
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Journal | :
Journal of magnetic resonance (San Diego, Calif. : 1997)
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Volume | :
257
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Number of Pages | :
45-50
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ISSN Number | :
1090-7807
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URL | :
https://linkinghub.elsevier.com/retrieve/pii/S1090-7807(15)00113-5
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DOI | :
10.1016/j.jmr.2015.05.005
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Short Title | :
J Magn Reson
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