FRISBI
EPR is the only method for the direct detection of paramagnetic species. Electron paramagnetic spectroscopy (EPR spectroscopy) applications span across a wide range of areas from quality control to molecular research in fields such as material research, structural biology and quantum physics. EPR experiments have provided invaluable information pertaining to metalloprotein structures and to the structures and processes in photosynthesis for example.
The SB²SM currently has three continuous wave EPR spectrometers functioning at X-band (9 GHz, two spectrometers Bruker ELEXYS E500 and a spectrometer Bruker ESP300E), as well as a Bruker e-scan bench spectrometer to assay radicals at room temperature. A pulse X-band spectrometer Bruker ELEXSYS E580 with ELDOR and ENDOR capabilities is also available. With respect to high-field EPR, the platform comprises a home-built continuous wave spectrometer operating at 95, 190 or 285 GHz, as well as a Bruker ELEXSYS E680 (with pulse ENDOR and PELDOR capabilities).
Several types of cavity are available at X-band: standard rectangular, dual-mode, high sensitivity.
| Spectrometer | Frequency | mode | Temperature |
Double Resonance
|
| e-scan | X-band –9 GHz | CW | Room T | |
| ESP300E | X-band –9 GHz | CW | Room T | |
| ELEXSYS E500 (2) | X-band –9 GHz | CW | ≥ 4.2 K | |
| ELEXSYS E580 | X-band –9 GHz | Pulse | ≥ 4.2 K | ENDOR/ELDOR |
| Home-built | 95, 190 and 285 GHz | CW | ≥ 1.8 K | |
| ELEXSYS E680 | W-band – 95 GHz | Pulse | ≥ 4.2 K | ENDOR/ELDOR |
EPR equipment located at the SB²SM is a unique platform for applications in Life Sciences. Local research projects making a heavy use of EPR are mainly centered around enzymatic systems associated with oxidative stress or photosynthesis:
- Catalytic mechanism of metalloproteins with iron or manganese: photosynthetic complexes, NO-synthase, cytochrome P450, mono and bifunctional peroxidases, superoxide dismutase
- Biomimetic chemical complexes
- Metal- peptide systems involved in neurodegeneration
- Oxidative stress in Plants
- Protein radicals involved in enzyme catalysis
Lambert, C., Beraldo, H., Lievre, N., Garnier-Suillerot, A., Dorlet, P., Salerno, M. (2013). Bis(thiosemicarbazone) copper complexes: mechanism of intracellular accumulation. J Biol Inorg Chem 18,59-69.
Santolini, J., Marechal, A., Boussac, A., Dorlet, P. (2013). EPR characterisation of the ferrous nitrosyl complex formed within the oxygenase domain of NO synthase. Chembiochem 14,1852-1857.
Boussac, A., Rutherford, A.W., Sugiura, M. (2015). Electron transfer pathways from the S2-states to the S3-states either after a Ca2+/Sr2+ or a Cl–/I– exchange in Photosystem II from Thermosynechococcus elongatus. Biochim. Biophys. Acta 1847, 576–586.
Burton, M. J., Kapetanaki, S. M., Chernova, T., Jamieson, A. G., Dorlet, P., Santolini, J., Moody, P. C., Mitcheson, J. S., Davies, N. W., Schmid, R., Raven, E. L., Storey, N. M. (2016). A heme-binding domain controls regulation of ATP-dependent potassium channels. Proc Natl Acad Sci U S A 113,3785-3790.
Low, M. L., Maigre, L., Tahir, M. I., Tiekink, E. R., Dorlet, P., Guillot, R., Ravoof, T. B., Rosli, R., Pages, J. M., Policar, C., Delsuc, N., Crouse, K. A. (2016). New insight into the structural, electrochemical and biological aspects of macroacyclic Cu(II) complexes derived from S-substituted dithiocarbazate schiff bases. Eur J Med Chem 120,1-12.
Weisslocker-Schaetzel, M., Lembrouk, M., Santolini, J., Dorlet, P. (2017). Revisiting the Val/Ile Mutation in Mammalian and Bacterial Nitric Oxide Synthases: A Spectroscopic and Kinetic Study. Biochemistry 56,748-756.