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MacMillan, Fraser 
ORCID: https://orcid.org/0000-0002-2410-4790, Kannt, Aimo, Behr, Julia, Prisner, Thomas and Michel, Hartmut
(1999)
Direct evidence for a tyrosine radical in the reaction of cytochrome c oxidase with hydrogen peroxide.
Biochemistry, 38 (29).
ISSN 0006-2960
Abstract
Cytochrome c oxidase (COX) catalyzes the reduction of oxygen to water, a process which is accompanied by the pumping of four protons across the membrane. Elucidation of the structures of intermediates in these processes is crucial for understanding the mechanism of oxygen reduction. In the work presented here, the reaction of HO with the fully oxidized protein at pH 6.0 has been investigated with electron paramagnetic resonance (EPR) spectroscopy. The results reveal an EPR signal with partially resolved hyperfine structure typical of an organic radical. The yield of this radical based on comparison with other paramagnetic centers in COX was ∼20%. Recent crystallographic data have shown that one of the CU ligands, His 276 (in the bacterial case), is cross-linked to Tyr 280 and that this cross-linked tyrosine is ideally positioned to participate in dioxygen activation. Here selectively deuterated tyrosine has been incorporated into the protein, and a drastic change in the line shape of the EPR signal observed above has been detected. This would suggest that the observed EPR signal does indeed arise from a tyrosine radical species. It would seem also quite possible that this radical is an intermediate in the mechanism of oxygen reduction.
| Item Type: | Article |
|---|---|
| Faculty \ School: | Faculty of Science > School of Chemistry (former - to 2024) |
| UEA Research Groups: | Faculty of Science > Research Groups > Biophysical Chemistry (former - to 2017) Faculty of Science > Research Groups > Chemistry of Life Processes Faculty of Science > Research Centres > Centre for Molecular and Structural Biochemistry Faculty of Science > Research Groups > Chemistry of Light and Energy |
| Depositing User: | Pure Connector |
| Date Deposited: | 21 Jan 2015 11:44 |
| Last Modified: | 25 Sep 2024 11:40 |
| URI: | https://ueaeprints.uea.ac.uk/id/eprint/51850 |
| DOI: | 10.1021/bi9911987 |
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