caa a22 4500 60554591X CHVBK 20210128100938.0 cr unu---uuuuu 210128e20150401xx s 000 0 eng 10.1007/s00723-014-0621-8 doi (NATIONALLICENCE)springer-10.1007/s00723-014-0621-8 Exploiting the Symmetry of the Resonator Mode to Enhance PELDOR Sensitivity [Elektronische Daten] [Enrico Salvadori, Mei Fung, Markus Hoffmann, Harry Anderson, Christopher Kay] Pulsed electron paramagnetic resonance (EPR) spectroscopy using microwaves at two frequencies can be employed to measure distances between pairs of paramagnets separated by up to 10nm. The method, combined with site-directed mutagenesis, has become increasingly popular in structural biology for both its selectivity and capability of providing information not accessible through more standard methods such as nuclear magnetic resonance and X-ray crystallography. Despite these advantages, EPR distance measurements suffer from poor sensitivity. One contributing factor is technical: since 65MHz typically separates the pump and detection frequencies, they cannot both be located at the center of the pseudo-Lorentzian microwave resonance of a single-mode resonator. To maximize the inversion efficiency, the pump pulse is usually placed at the center of the resonance, while the observer frequency is placed in the wing, with consequent reduction in sensitivity. Here, we consider an alternative configuration: by spacing pump and observer frequencies symmetrically with respect to the microwave resonance and by increasing the quality factor, valuable improvement in the signal-to-noise ratio can be obtained. The Author(s), 2014 Salvadori Enrico London Centre for Nanotechnology, University College London, 17-19 Gordon Street, WC1H 0AH, London, UK aut Fung Mei Institute of Structural and Molecular Biology, University College London, Gower Street, WC1E 6BT, London, UK aut Hoffmann Markus Chemistry Research Laboratory, Department of Chemistry, University of Oxford, South Parks Road, OX1 3TA, Oxford, UK aut Anderson Harry Chemistry Research Laboratory, Department of Chemistry, University of Oxford, South Parks Road, OX1 3TA, Oxford, UK aut Kay Christopher London Centre for Nanotechnology, University College London, 17-19 Gordon Street, WC1H 0AH, London, UK aut Applied Magnetic Resonance Springer Vienna 46/4(2015-04-01), 359-368 0937-9347 46:4<359 2015 46 723 https://doi.org/10.1007/s00723-014-0621-8 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s00723-014-0621-8 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Salvadori Enrico London Centre for Nanotechnology, University College London, 17-19 Gordon Street, WC1H 0AH, London, UK aut NATIONALLICENCE 700 1- Fung Mei Institute of Structural and Molecular Biology, University College London, Gower Street, WC1E 6BT, London, UK aut NATIONALLICENCE 700 1- Hoffmann Markus Chemistry Research Laboratory, Department of Chemistry, University of Oxford, South Parks Road, OX1 3TA, Oxford, UK aut NATIONALLICENCE 700 1- Anderson Harry Chemistry Research Laboratory, Department of Chemistry, University of Oxford, South Parks Road, OX1 3TA, Oxford, UK aut NATIONALLICENCE 700 1- Kay Christopher London Centre for Nanotechnology, University College London, 17-19 Gordon Street, WC1H 0AH, London, UK aut NATIONALLICENCE 773 0- Applied Magnetic Resonance Springer Vienna 46/4(2015-04-01), 359-368 0937-9347 46:4<359 2015 46 723