Proton transfer in ba 3 cytochrome c oxidase from Thermus thermophilus

Christoph Von Ballmoos, Pia Ädelroth, Robert B. Gennis, Peter Brzezinski

Research output: Contribution to journalReview articlepeer-review


The respiratory heme-copper oxidases catalyze reduction of O 2 to H 2O, linking this process to transmembrane proton pumping. These oxidases have been classified according to the architecture, location and number of proton pathways. Most structural and functional studies to date have been performed on the A-class oxidases, which includes those that are found in the inner mitochondrial membrane and bacteria such as Rhodobacter sphaeroides and Paracoccus denitrificans (aa 3-type oxidases in these bacteria). These oxidases pump protons with a stoichiometry of one proton per electron transferred to the catalytic site. The bacterial A-class oxidases use two proton pathways (denoted by letters D and K, respectively), for the transfer of protons to the catalytic site, and protons that are pumped across the membrane. The B-type oxidases such as, for example, the ba 3 oxidase from Thermus thermophilus, pump protons with a lower stoichiometry of 0.5 H +/electron and use only one proton pathway for the transfer of all protons. This pathway overlaps in space with the K pathway in the A class oxidases without showing any sequence homology though. Here, we review the functional properties of the A- and the B-class ba 3 oxidases with a focus on mechanisms of proton transfer and pumping. This article is part of a Special Issue entitled: Respiratory Oxidases.

Original languageEnglish (US)
Pages (from-to)650-657
Number of pages8
JournalBiochimica et Biophysica Acta - Bioenergetics
Issue number4
StatePublished - Apr 2012


  • Electrochemical gradient
  • Electron transfer
  • Energy conservation
  • Kinetics
  • Membrane protein
  • Respiratory oxidase

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Cell Biology


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