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A simple double quantum coherence ESR sequence that minimizes nuclear modulations in Cu(2+)-ion based distance measurements.

Author
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
Journal
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Journal of magnetic resonance (San Diego, Calif. : 1997)
Volume
:
257
Number of Pages
:
45-50
ISSN Number
:
1090-7807
URL
:
https://linkinghub.elsevier.com/retrieve/pii/S1090-7807(15)00113-5
DOI
:
10.1016/j.jmr.2015.05.005
Short Title
:
J Magn Reson
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