The intrinsic stability of the second intermediate following the dioxygen-bound form in the O2 reduction by cytochrome c oxidase.
Aeration of a two-electron reduced cytochrome c oxidase provides a species with two Raman bands at 804 and 356 cm(-1), identifying it as the second intermediate following the O2-bound species in the enzymatic O2 reduction process. It degrades directly to the fully oxidized form with a half-life time of 70 min at pH 8.0. The stability suggests an effective insulation for the active site in an extremely high oxidation state (Fe4+ with one oxidative equivalent nearby) against spontaneous electron leaks, which would dissipate proton motive force. The formation and degradation of the second intermediate are pH-dependent.
Oda
Kenji
K
Chemistry Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439, USA.
Ogura
Takashi
T
Appelman
Evan H
EH
Yoshikawa
Shinya
S
D000818:Animals; D002417:Cattle; D003576:Electron Transport Complex IV / Q000737:chemistry*; D004583:Electrons; D006863:Hydrogen-Ion Concentration; D009206:Myocardium / Q000378:metabolism; D010100:Oxygen / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D011522:Protons; D013059:Spectrum Analysis, Raman; D013997:Time Factors
D011522:Protons; D003576:Electron Transport Complex IV; D010100:Oxygen