Unpaired electrons in (bio)materials

Event Date
Monday, 31 January 2022 - 12:00pm
Maxie Roessler

Maxie M. Roessler (Chemistry, Imperial College London)

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Electron spins permeate every aspect of science and influence numerous processes: they underpin transition metal chemistry and biochemistry, mediate photosynthesis and photovoltaics and are paramount in the field of quantum information, to name but a few. Electron paramagnetic resonance (EPR) spectroscopy detects unpaired electrons and provides detailed information on structure and bonding of paramagnetic species.1

In this talk, I will focus on how we can exploit that EPR is blind to paired electrons to study very large and complicated biomolecules and gain detailed mechanistic insight. Using methodologies developed for respiratory complex I (an essential enzyme for ATP production in mitochondria)2 and EPR instrument advances to work with very low spin concentrations,3 we recently determined and assigned the magnetic properties of the iron-sulfur clusters in photosynthetic complex I, placing it on the ‘bioenergetic map’ of photosynthesis.4

I will also give a brief overview of some of the ongoing work at the Centre for Pulse EPR (PEPR), and some of the unique capabilities of this facility.

(1)         Roessler, M. M.; Salvadori, E. Principles and Applications of EPR Spectroscopy in the Chemical Sciences. Chemical Society Reviews. Royal Society of Chemistry April 21, 2018, pp 2534–2553. https://doi.org/10.1039/c6cs00565a.

(2)         Le Breton, N.; Wright, J. J.; Jones, A. J. Y.; Salvadori, E.; Bridges, H. R.; Hirst, J.; Roessler, M. M. Using Hyperfine Electron Paramagnetic Resonance Spectroscopy to Define the Proton-Coupled Electron Transfer Reaction at Fe-S Cluster N2 in Respiratory Complex I. J. Am. Chem. Soc. 2017, 139 (45), 16319–16326. https://doi.org/10.1021/jacs.7b09261.

(3)         Šimėnas, M.; O’Sullivan, J.; Zollitsch, C. W.; Kennedy, O.; Seif-Eddine, M.; Ritsch, I.; Hülsmann, M.; Qi, M.; Godt, A.; Roessler, M. M.; Jeschke, G.; Morton, J. J. L. A Sensitivity Leap for X-Band EPR Using a Probehead with a Cryogenic Preamplifier. J. Magn. Reson. 2021, 322, 106876. https://doi.org/10.1016/j.jmr.2020.106876.

(4)         Richardson, K. H.; Wright, J. J.; Šimėnas, M.; Thiemann, J.; Esteves, A. M.; McGuire, G.; Myers, W. K.; Morton, J. J. L.; Hippler, M.; Nowaczyk, M. M.; Hanke, G. T.; Roessler, M. M. Functional Basis of Electron Transport within Photosynthetic Complex I. Nat. Commun. 2021 121 2021, 12 (1), 1–8. https://doi.org/10.1038/s41467-021-25527-1.