Protein structural dynamics revealed by site-directed spin labeling and multifrequency EPR

Yuri E. Nesmelov, David D. Thomas

Research output: Contribution to journalReview articlepeer-review

24 Scopus citations


Multifrequency electron paramagnetic resonance (EPR), combined with site-directed spin labeling, is a powerful spectroscopic tool to characterize protein dynamics. The lineshape of an EPR spectrum reflects combined rotational dynamics of the spin probe's local motion within a protein, reorientations of protein domains, and overall protein tumbling. All these motions can be restricted and anisotropic, and separation of these motions is important for thorough characterization of protein dynamics. Multifrequency EPR distinguishes between different motions of a spin-labeled protein, due to the frequency dependence of EPR resolution to fast and slow motion of a spin probe. This gives multifrequency EPR its unique capability to characterize protein dynamics in great detail. In this review, we analyze what makes multifrequency EPR sensitive to different rates of spin probe motion and discuss several examples of its usage to separate spin probe dynamics and overall protein dynamics, to characterize protein backbone dynamics, and to resolve protein conformational states.

Original languageEnglish (US)
Pages (from-to)91-99
Number of pages9
JournalBiophysical Reviews
Issue number2
StatePublished - 2010

Bibliographical note

Funding Information:
This work was supported by NIH grants AR53562 (Y.E.N.) and AR32961 (D.D.T.). NLSL and NLSL SRLS software was kindly provided by Dr. Z. Liang (Cornell University). We appreciate discussions with Dr. D. Budil (Northeastern University), Dr. Z. Liang and Dr. J.H. Freed (Cornell University).


  • Multifrequency electron paramagnetic resonance (EPR)
  • Protein dynamics
  • Site-directed spin labeling
  • Spin probe motion


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