DEER sensitivity between iron centers and nitroxides in heme-containing proteins improves dramatically using broadband, high-field EPR

Claire Louise Motion, Janet Eleanor Lovett, Stacey Bell, Scott Lindsay Cassidy, Paul Alexander Sawchuk Cruickshank, David Robert Bolton, Robert Iain Hunter, Hassane El Mkami, Sabine Van Doorslaer, Graham Murray Smith

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28 Citations (Scopus)
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Abstract

This work demonstrates the feasibility of making sensitive nanometer distancemeasurements between Fe(III) heme centers and nitroxide spin labels in proteins using the double electron-electron resonance (DEER) pulsed EPR technique at 94 GHz. Techniques to measure accurately long distances in many classes of heme proteins using DEER are currently strongly limited by sensitivity. In this paper we demonstrate sensitivity gains of more than 30times compared with previous lower frequency (X-band) DEER measurements on both human neuroglobin and sperm whale myoglobin. This is achieved by: taking advantage of recent instrumental advances; employing wideband excitation techniques based on composite pulses and exploiting more favorable relaxation properties of low-spin Fe(III) in high magnetic fields. This gain in sensitivity potentially allows the DEER technique to be routinely used as a sensitive probe of structure and conformation in the large number of heme and many other metalloproteins.
Original languageEnglish
Pages (from-to)1411-1415
Number of pages5
JournalJournal of Physical Chemistry Letters
Volume7
Issue number8
Early online date1 Apr 2016
DOIs
Publication statusPublished - 21 Apr 2016

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