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

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Original languageEnglish
Pages (from-to)1111-1115
JournalBiochimica et Biophysica Acta: Bioenergetics
Issue number8
Early online date17 Feb 2016
Publication statusPublished - Aug 2016
Publication typeA1 Journal article-refereed


The active site of cytochrome c oxidase (CcO) comprises an oxygen-binding heme, a nearby copper ion (CuB), and a tyrosine residue that is covalently linked to one of the histidine ligands of CuB. 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.

ASJC Scopus subject areas


  • Electron transfer, Neutral tyrosyl radical, Proton pumping

Publication forum classification

Field of science, Statistics Finland