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Stabilization of the peroxy intermediate in the oxygen splitting reaction of cytochrome cbb3

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Original languageEnglish
Pages (from-to)813-818
Number of pages6
JournalBiochimica et Biophysica Acta: Bioenergetics
Issue number7
Publication statusPublished - Jul 2011
Publication typeA1 Journal article-refereed


The proton-pumping cbb3-type cytochrome c oxidases catalyze cell respiration in many pathogenic bacteria. For reasons not yet understood, the apparent dioxygen (O2) affinity in these enzymes is very high relative to other members of the heme-copper oxidase (HCO) superfamily. Based on density functional theory (DFT) calculations on intermediates of the oxygen scission reaction in active-site models of cbb3- and aa 3-type oxidases, we find that a transient peroxy intermediate (I P, Fe[III]-OOH-) is ~ 6 kcal/mol more stable in the former case, resulting in more efficient kinetic trapping of dioxygen and hence in a higher apparent oxygen affinity. The major molecular basis for this stabilization is a glutamate residue, polarizing the proximal histidine ligand of heme b3 in the active site.

ASJC Scopus subject areas


  • cbb-type cytochrome c oxidase, Density Functional Theory (DFT), Heme-copper oxidases, Oxygen activation, Oxygen affinity