The role of the K-channel and the active-site tyrosine in the catalytic mechanism of cytochrome c oxidase

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Sharma , V & Wikstrom , M 2016 , ' The role of the K-channel and the active-site tyrosine in the catalytic mechanism of cytochrome c oxidase ' Biochimica et Biophysica Acta. Bioenergetics , vol. 1857 , no. 8 , pp. 1111-1115 . DOI: 10.1016/j.bbabio.2016.02.008

Title: The role of the K-channel and the active-site tyrosine in the catalytic mechanism of cytochrome c oxidase
Author: Sharma, Vivek; Wikstrom, Marten
Other contributor: University of Helsinki, Institute of Biotechnology
University of Helsinki, Institute of Biotechnology

Date: 2016-08
Language: eng
Number of pages: 5
Belongs to series: Biochimica et Biophysica Acta. Bioenergetics
ISSN: 0005-2728
DOI: https://doi.org/10.1016/j.bbabio.2016.02.008
URI: http://hdl.handle.net/10138/173934
Abstract: The active site of cytochrome c oxidase (CcO) comprises an oxygen-binding heme, a nearby copper ion (Cue), and a tyrosine residue that is covalently linked to one of the histidine ligands of Cu-B. Two proton-conducting pathways are observed in CcO, namely the D-and the K-channels, which are used to transfer protons either to the active site of oxygen reduction (substrate protons) or for pumping. Proton transfer through the D-channel is very fast, and its role in efficient transfer of both substrate and pumped protons is well established. However, it has not been fully clear why a separate K-channel is required, apparently for the supply of substrate protons only. In this work, we have analysed the available experimental and computational data, based on which we provide new perspectives on the role of the K-channel. Our analysis suggests that proton transfer in the K-channel may be gated by the protonation state of the active-site tyrosine (Tyr244) and that the neutral radical form of this residue has a more general role in the CcO mechanism than thought previously. This article is part of a Special Issue entitled 'EBEC 2016: 19th European Bioenergetics Conference, Riva del Garda, Italy, July 2-6, 2016', edited by Prof. Paolo Bernardi. (C) 2016 Elsevier B.V. All rights reserved.
Subject: Electron transfer
Proton pumping
Neutral tyrosyl radical
COUPLED ELECTRON-TRANSFER
PARACOCCUS-DENITRIFICANS
RHODOBACTER-SPHAEROIDES
PROTON TRANSLOCATION
OXYGEN REDUCTION
CYCLE
HEME
STATE
TIME
1182 Biochemistry, cell and molecular biology
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