Open AccessSingle catalytic site model for the oxidation of ferrocytochrome c by mitochondrial cytochrome c oxidase.
Author(s) -
Samuel H. Speck,
David Dye,
E. Margoliash
Publication year - 1984
Publication title -
proceedings of the national academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.81.2.347
Subject(s) - cytochrome c oxidase , cytochrome c , chemistry , cytochrome , reaction rate constant , oxidase test , coenzyme q – cytochrome c reductase , dissociation constant , catalysis , oxidoreductase , cytochrome c1 , electron transport chain , cytochrome c peroxidase , kinetics , electron transport complex iv , stereochemistry , photochemistry , biochemistry , enzyme , mitochondrion , physics , receptor , quantum mechanics
A single catalytic site model is proposed to account for the multiphasic kinetics of oxidation of ferrocytochrome c by cytochrome c oxidase (ferrocytochrome c:oxygen oxidoreductase, EC 1.9.3.1). This model involves nonproductive binding of substrate to sites near the catalytic site on cytochrome c oxidase for cytochrome c, decreasing the binding constant for cytochrome c at the catalytic site. This substrate inhibition results in an increase in the first-order rate constant for the dissociation of the ferricytochrome c-cytochrome c oxidase complex, the rate-limiting step in the steady-state turnover of electrons between cytochrome c and cytochrome c oxidase in the spectrophotometric assay, yielding increases in the initial rate as well as the Michaelis constant--namely, multiple kinetic phases.
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