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Volume 24 (2010), Issue 3-4, Pages 283-288

Accessing the distance range of interest in biomolecules: Site-directed spin labeling and DEER spectroscopy

Sabine Böhme,1 Heinz-Jürgen Steinhoff,1 and Johann P. Klare1,2

1Department of Physics, University of Osnabrück, Osnabrück, Germany
2Department of Physics, University of Osnabrück, Barbarastrasse 7, D-49069 Osnabrück, Germany

Copyright © 2010 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Investigations on the structure and function of biomolecules often depend on the availability of topological information to build up structural models or to characterize conformational changes during function. Electron paramagnetic resonance (EPR) spectroscopy in combination with site–directed spin labeling (SDSL) allow to determine intra- and intermolecular distances in the range from 4–70 Å, covering the range of interest for biomolecules. The approach does not require crystalline samples and is well suited also for molecules exhibiting intrinsic flexibility. This article is intended to give an overview on pulsed EPR in conjunction with SDSL to study protein interactions as well as conformational changes, exemplified on the tRNA modifying enzyme MnmE.