Structural information from orientationally selective DEER spectroscopy

Lovett, J. E., Bowen, A. M., Timmel, C. R., Jones, M. W., Dilworth, J. R., Caprotti, D., Bell, S. G., Wong, L. L. and Harmer, J. (2009) Structural information from orientationally selective DEER spectroscopy. Physical Chemistry Chemical Physics, 11 31: 6840-6848. doi:10.1039/b907010a

Author Lovett, J. E.
Bowen, A. M.
Timmel, C. R.
Jones, M. W.
Dilworth, J. R.
Caprotti, D.
Bell, S. G.
Wong, L. L.
Harmer, J.
Title Structural information from orientationally selective DEER spectroscopy
Journal name Physical Chemistry Chemical Physics   Check publisher's open access policy
ISSN 1463-9076
Publication date 2009-01-01
Year available 2009
Sub-type Article (original research)
DOI 10.1039/b907010a
Open Access Status
Volume 11
Issue 31
Start page 6840
End page 6848
Total pages 9
Place of publication Cambridge, United Kingdom
Publisher R S C Publications
Language eng
Abstract Double electron–electron resonance (DEER) spectroscopy can determine, from measurement of the dipolar interaction, the distance and orientation between two paramagnetic centres in systems lacking long-range order such as powders or frozen solution samples. In spin systems with considerable anisotropy, the microwave pulses excite only a fraction of the electron paramagnetic resonance (EPR) spectrum and the resulting orientation selection needs to be explicitly taken into account if a meaningful distance and orientation is to be determined. Here, a general method is presented to analyze the dipolar interaction between two paramagnetic spin centres from a series of DEER traces recorded so that different orientations of the spin–spin vector are sampled. Delocalised spin density distributions and spin projection factors (as for example in iron–sulfur clusters), are explicitly included. Application of the analysis to a spin-labelled flavoprotein reductase/reduced iron–sulfur ferredoxin protein complex and a bi-radical with two Cu(II) ions provides distance and orientation information between the radical centres. In the protein complex this enables the protein–protein binding geometry to be defined. Experimentally, orientationally selective DEER measurements are possible on paramagnetic systems where the resonator bandwidth allows the frequencies of pump and detection pulses to be separated sufficiently to excite enough orientations to define adequately the spin–spin vector.
Keyword Electron double-resonance
Distance measurements
Spin resonance
Rhodopseudomonas palustris
Q-Index Code C1
Q-Index Status Provisional Code
Grant ID P41 RR-01081
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: Centre for Advanced Imaging Publications
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