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

Abstract: This work demonstrates the feasibility of making sensitive nanometer distance measurements 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...

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Bibliographic Details
Published in:The Journal of Physical Chemistry Letters
Main Authors: Motion, Claire L., Lovett, Janet E., Bell, Stacey, Cassidy, Scott L., Cruickshank, Paul A.S., Bolton, David R., Hunter, Robert I., El Mkami, Hassane, Van Doorslaer, Sabine, Smith, Graham M.
Format: Article in Journal/Newspaper
Language:English
Published: 2016
Subjects:
Physics
Sperm whale
Online Access:https://hdl.handle.net/10067/1411890151162165141
https://repository.uantwerpen.be/docman/irua/bc623d/141189.pdf
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Summary:Abstract: This work demonstrates the feasibility of making sensitive nanometer distance measurements 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 30 times 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.

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