Electron Paramagnetic Resonance (EPR) spectroscopy is a powerful technique for studying molecules with unpaired electrons (i.e. radicals). The technique is analogous to NMR, but has superior sensitivity and no real size limit to the samples that can be studied, with many measurements made on frozen samples. EPR is particularly useful for the study of metallo-proteins, such as cytochromes and iron-sulfur proteins, and those enzymes with (quasi)stable radical intermediates such as flavoenzymes or photosynthetic complexes.
The MIB EPR facility’s focus is the study of radical/metal-containing biomolecules such as cofactors, metallo-proteins and radical enzymes. The facility houses a Bruker ELEXSYS E580 spectrometer operating at X-band (~ 9.5 GHz) that is capable of performing both continuous wave (CW) and pulsed EPR measurements at temperatures ranging from ~ 5K to RT.
- Continuous-wave (CW) EPR
- Electron nuclear double resonance techniques (ENDOR)
- Electron spin echo envelope modulation (ESEEM)
- Electron-electron double resonance (ELDOR/PELDOR/DEER)
- ELDOR detected NMR (EDNMR)
- Rapid-freeze quench with subsequent EPR characterization (CW or pulsed)
- Optically-excited CW and time-resolved EPR
- Payne et al. (2015) Reductive dehalogenase structure suggests a mechanism for B12-dependent dehalogenation. Nature 517, 513-516
- Sobolewska-Stawiarz et al. (2014) Energy landscapes and catalysis in nitric-oxide synthase. J. Biol. Chem. 289, 11725-11738
- Belcher et al. (2014) Structure and biochemical properties of the alkene producing cytochrome P450 OleTJE (CYP152L1) from the Jeotgalicoccus sp. 8456 bacterium. J. Biol. Chem. 289, 6535-6550.
- Moore et al. (2013) Elucidation of the anaerobic pathway for the corrin component of cobalamin (vitamin B12). Proc. Natl. Acad. Sci. USA 110, 14906-14911
The MIB EPR Facility offers a range of advanced CW and pulsed EPR experiments and can operate as either a service or as part of a longer-term collaboration. Typical sample requirements are comparable to NMR for pulsed experiments (roughly 300 μl at 500-600 μM), which are performed on frozen samples. Less concentrated sample is typically required for CW measurements, which can be run at room temperature and/or cryogenic temperatures depending on the nature of the sample.
We work closely with the Molecular Magnetism group and the National EPR facility in the Photon Science Institute (http://www.epr.chemistry.manchester.ac.uk/) and can arrange access to the spectrometers housed there, which include:
- Bruker Elexsys E580 spectrometers operating at S- and Q-band.
- Bruker Elexsys E600 spectrometer with a 6 T superconducting magnet for CW W-band measurements