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Two‐electron reduction of cytochrome c oxidase triggers a conformational transition
Author(s) -
Scholes Charles P.,
Malmström Bo G.
Publication year - 1986
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 - 10.1016/0014-5793(86)81197-8
Subject(s) - cytochrome c oxidase , cyanide , conformational change , chemistry , cytochrome , intramolecular force , electron transport chain , oxidase test , cytochrome c , electron transport complex iv , electron transfer , photochemistry , biophysics , crystallography , stereochemistry , enzyme , biochemistry , inorganic chemistry , biology , mitochondrion
The slow increase of a cyanide‐induced optical change at 437 nm following rapid cyanide inhibition of cytochrome oxidase has been followed as a function of the number of electrons donated from ferrocytochrome c to cytochrome a and Cu a . The initial rate of optical change is a parabolic function of this number. The results have been analyzed in terms of a model where addition of electrons causes a conformational transition allowing rapid cyanide binding. The binding is followed by a slow intramolecular reaction responsible for the optical change. The analysis demonstrates that only molecules with both cytochrome a and Cu a reduced can undergo the conformational change, which is suggested to be involved in the proton‐pump mechanism of the oxidase.