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The intrinsic stability of the second intermediate following the dioxygen‐bound form in the O 2 reduction by cytochrome c oxidase
Author(s) -
Oda Kenji,
Ogura Takashi,
Appelman Evan H,
Yoshikawa Shinya
Publication year - 2004
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2004.06.036
Subject(s) - chemistry , cytochrome c oxidase , electron transport complex iv , cytochrome , oxidase test , photochemistry , cytochrome c , electron transport chain , raman spectroscopy , oxygen , oxidative phosphorylation , proton , stereochemistry , enzyme , biochemistry , mitochondrion , organic chemistry , physics , quantum mechanics , optics
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 O 2 ‐bound species in the enzymatic O 2 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 (Fe 4+ 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.