Q(H)(center dot-) ubisemiquinone radical in the bo(3)-type ubiquinol oxidase studied by pulsed electron paramagnetic resonance and hyperfine sublevel correlation spectroscopy

Grimaldi, S., Macmillan, F., Ostermann, T., Ludwig, B., Michel, H. and Prisner, T. (2001) Q(H)(center dot-) ubisemiquinone radical in the bo(3)-type ubiquinol oxidase studied by pulsed electron paramagnetic resonance and hyperfine sublevel correlation spectroscopy. Biochemistry, 40 (4). pp. 1037-1043. ISSN 0006-2960

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Abstract

The high-affinity Q(H) ubiquinone-binding site in the bo(3) ubiquinol oxidase from Escherichia coli has been characterized by an investigation of the native ubiquinone radical anion Q(H)(.-) by pulsed electron paramagnetic resonance (EPR) spectroscopy. One- and two-dimensional electron spin-echo envelope modulation (ESEEM) spectra reveal strong interactions of the unpaired electron of Q(H)(.-) with a nitrogen nucleus from the surrounding protein matrix. From analysis of the experimental data, the N-14 nuclear quadrupolar parameters have been determined: kappa = e(2)qQ/4h = 0.93 MHz and eta = 0.50. This assignment is confirmed by hyperfine sublevel correlation (HYSCORE) spectroscopy. On the basis of a comparison of these data with those obtained previously for other membrane-protein bound semiquinone radicals and model systems, this nucleus is assigned tu a protein backbone nitrogen. This result is discussed with regard to the location and potential function of Q(H) in the enzyme.

Item Type: Article
Faculty \ School: Faculty of Science > School of Chemistry
Depositing User: Rachel Smith
Date Deposited: 19 Jul 2011 12:10
Last Modified: 21 Dec 2018 15:30
URI: https://ueaeprints.uea.ac.uk/id/eprint/33886
DOI:

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