Articles | Volume 6, issue 2
https://doi.org/10.5194/mr-6-183-2025
https://doi.org/10.5194/mr-6-183-2025
Research article
 | 
17 Jul 2025
Research article |  | 17 Jul 2025

Determining large hyperfine interactions of a model flavoprotein in the semiquinone state using pulse EPR (electron paramagnetic resonance) techniques

Jesús I. Martínez, Susana Frago, Milagros Medina, and Inés García-Rubio

Related subject area

Field: EPR | Topic: Applications – biological macromolecules
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Magn. Reson., 1, 301–313, https://doi.org/10.5194/mr-1-301-2020,https://doi.org/10.5194/mr-1-301-2020, 2020
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Cited articles

Barquera, B., Morgan, J. E., Lukoyanov, D., Scholes, C. P., Gennis, R. B., and Nilges, M. J.: X- and W-band EPR and Q-band ENDOR studies of the flavin radical in the Na+-translocating NADH:quinone oxidoreductase from Vibrio cholerae, J. Am. Chem. Soc., 125, 265–275, https://doi.org/10.1021/ja0207201, 2003. 
Beaupre, B. A. and Moran, G. R.: N5 Is the New C4a: Biochemical Functionalization of Reduced Flavins at the N5 Position, Front. Mol. Biosci., 7, 598912, https://doi.org/10.3389/fmolb.2020.598912, 2020. 
Bestsova, Y. V., Kulik, L. V., Mamedov, M. D., Baykov, A. A., and Bogachev, A. V.: Flavodoxin with and air-stable flavin semiquinone in a green sulfur bacterium, Photosynth. Res., 142, 127–136, https://doi.org/10.1007/s11120-019-00658-1, 2019. 
Brosi, R., Bittl, R., and Engelhard, C.: EPR of flavoproteins, Methods in Mol. Biol., 1146, 341–360, https://doi.org/10.1007/978-1-4939-0452-5_13, 2014. 
Buey, R. M., Fernández-Justel, D., González-Holgado, G., Martínez-Júlvez, M., González-López, A., Velázquez-Campoy, A., Medina, M., Buchanan, B. B., and Balsera, M.: Unexpected diversity of ferredoxin-dependent thioredoxin reductases in cyanobacteria, Plant Physiol., 186, 285–296, https://doi.org/10.1093/plphys/kiab072, 2021. 
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Short summary
Flavoproteins are essential biomolecules involved in many vital processes. Understanding their reactivity requires study of their intermediate semiquinone form. Using advanced spectroscopy and isotopic labeling, we measured key interactions within this state, uncovering subtle changes in the distribution of electron density. These findings refine our understanding of flavoprotein function and highlight the value of combining experiments and computations for studying complex biological systems.
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