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Oxidative Stress impairs the respiratory process of ATP synthesis
Author(s) -
Reynafarje Baltazar
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a296-a
Subject(s) - atp synthase , chemistry , oxidative phosphorylation , electron transport chain , biophysics , chemiosmosis , mitochondrion , respiratory chain , cytochrome c oxidase , adenosine triphosphate , stoichiometry , biochemistry , enzyme , biology , organic chemistry
The extent and initial rates of H + translocation, O 2 uptake and ATP synthesis were determined in reactions catalyzed by intact mitochondria, sub‐mitochondrial particles and cytochrome c oxidase embedded in liposomes. The following findings were made. 1. The rates of ATP synthesis are compatible with the extremely fast rates of electron flow and orders of magnitude higher than the rates of O 2 uptake during state‐3 metabolic conditions. 2. The free energy of electron flow is essential not only for the release of products from the synthase but for the actual synthesis of ATP from ADP and Pi. 3. The ATP/O stoichiometry (number of molecules of ATP formed per atom of O 2 simultaneously consumed) varies depending not only on the redox potential (ΔE h ) but above all on the degree of reduction of O 2 and the availability or structurally labile H + in close vicinity with the catalytic sites of the oxidase. 4. The cooperative synthesis of ATP has a Hill coefficient, n, of 3.0 and a P 50 for ADP that regardless of the ΔE h decreases as the concentration of O 2 increases. It is concluded that the synthesis of ATP is controlled by the free energy derived from the complete reduction of O 2 with protons released from the membrane itself during the conformational changes induced by the flow of electrons. Self‐support