Identifying conformational changes with site-directed spin labeling

Nat Struct Biol. 2000 Sep;7(9):735-9. doi: 10.1038/78956.


Site-direct spin labeling combined with electron paramagnetic resonance (EPR) spectroscopy is a powerful tool for detecting structural changes in proteins. This review provides examples that illustrate strategies for interpreting the data in terms of specific rearrangements in secondary and tertiary structure. The changes in the mobility and solvent accessibility of the spin label side chains, and in the distances between spin labels, report (i) rigid body motions of alpha-helices and beta-strands (ii) relative movements of domains and (iii) changes in secondary structure. Such events can be monitored in the millisecond time-scale, making it possible to follow structural changes during function. There is no upper limit to the size of proteins that can be investigated, and only 50-100 picomoles of protein are required. These features make site-directed spin labeling an attractive approach for the study of structure and dynamics in a wide range of systems.

Publication types

  • Review

MeSH terms

  • Animals
  • Bacterial Outer Membrane Proteins
  • Electron Spin Resonance Spectroscopy / methods*
  • Escherichia coli Proteins*
  • Membrane Transport Proteins
  • Models, Molecular
  • Motion
  • Muramidase / chemistry
  • Muramidase / metabolism
  • Protein Conformation
  • Proteins / chemistry*
  • Proteins / metabolism*
  • Receptors, Peptide / chemistry
  • Receptors, Peptide / metabolism
  • Rhodopsin / chemistry
  • Rhodopsin / metabolism
  • Spin Labels*
  • Vitamin B 12 / metabolism


  • Bacterial Outer Membrane Proteins
  • BtuB protein, E coli
  • Escherichia coli Proteins
  • Membrane Transport Proteins
  • Proteins
  • Receptors, Peptide
  • Spin Labels
  • Rhodopsin
  • Muramidase
  • Vitamin B 12