An oxo-ferryl tryptophan radical catalytic intermediate in cytochrome c and quinol oxidases trapped by microsecond freeze-hyperquenching (MHQ)

Wiertz, Frank G. M., Richter, Oliver-Matthias H., Cherepanov, Alexey V., MacMillan, Fraser, Ludwig, Bernd and de Vries, Simon (2004) An oxo-ferryl tryptophan radical catalytic intermediate in cytochrome c and quinol oxidases trapped by microsecond freeze-hyperquenching (MHQ). FEBS Letters, 575 (1-3). pp. 127-130. ISSN 0014-5793

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Abstract

The pre-steady state reaction kinetics of the reduction of molecular oxygen catalyzed by fully reduced cytochrome oxidase from Escherichia coli and Paracoccus denitrificans were studied using the newly developed microsecond freeze-hyperquenching mixing-and-sampling technique. Reaction samples are prepared 60 and 200 μs after direct mixing of dioxygen with enzyme. Analysis of the reaction samples by low temperature UV-Vis spectroscopy indicates that both enzymes are trapped in the P state. EPR spectroscopy revealed the formation of a mixture of two radicals in both enzymes. Based on its apparent g-value and lineshape, one of these radicals is assigned to a weakly magnetically coupled oxo-ferryl tryptophan cation radical. Implications for the catalytic mechanism of cytochrome oxidases are discussed.

Item Type: Article
Faculty \ School: Faculty of Science > School of Chemistry
Related URLs:
Depositing User: Pure Connector
Date Deposited: 21 Jan 2015 11:44
Last Modified: 21 Sep 2020 23:41
URI: https://ueaeprints.uea.ac.uk/id/eprint/51846
DOI: 10.1016/j.febslet.2004.08.048

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