Distinguishing between Cl - and O 2- 2 as the bridging element between Fe 3+ and Cu 2+ in resting-oxidized cytochrome c oxidase

Michihiro Suga, Naomine Yano, Kazumasa Muramoto, Kyoko Shinzawa-Itoh, Tomoko Maeda, Eiki Yamashita, Tomitake Tsukihara, Shinya Yoshikawa

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14 Citations (Scopus)


Fully oxidized cytochrome c oxidase (CcO) under enzymatic turnover is capable of pumping protons, while fully oxidized CcO as isolated is not able to do so upon one-electron reduction. The functional difference is expected to be a consequence of structural differences: [Fe 3+-OH -] under enzymatic turnover versus [Fe 3+-O 2 2--Cu 2+] for the as-isolated CcO. However, the electron density for O2 2- is equally assignable to Cl -. An anomalous dispersion analysis was performed in order to conclusively demonstrate the absence of Cl - between the Fe 3+ and Cu 2+. Thus, the peroxide moiety receives electron equivalents from cytochrome c without affecting the oxidation states of the metal sites. The metal-site reduction is coupled to the proton pump.

Original languageEnglish
Pages (from-to)742-744
Number of pages3
JournalActa Crystallographica Section D: Biological Crystallography
Issue number8
Publication statusPublished - Aug 2011
Externally publishedYes


  • cytochrome c oxidase

ASJC Scopus subject areas

  • Structural Biology


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