Format

Send to

Choose Destination
See comment in PubMed Commons below
Int J Med Sci. 2008 Jun 9;5(3):143-51.

Oxidative phosphorylation: kinetic and thermodynamic correlation between electron flow, proton translocation, oxygen consumption and ATP synthesis under close to in vivo concentrations of oxygen.

Author information

  • 1Johns Hopkins University School of Medicine, Department of Biological Chemistry, Baltimore, Maryland 21205, USA.

Abstract

For the fist time the mitochondrial process of oxidative phosphorylation has been studied by determining the extent and initial rates of electron flow, H+ translocation, O2 uptake and ATP synthesis under close to in vivo concentrations of oxygen. The following novel results were obtained. 1) The real rates of O2 uptake and ATP synthesis are orders of magnitude higher than those observed under state-3 metabolic conditions. 2) The phosphorylative process of ATP synthesis is neither kinetically nor thermodynamically related to the respiratory process of H+ ejection. 3) The ATP/O stoichiometry is not constant but varies depending on all, the redox potential (DeltaE(h)), the degree of reduction of the membrane and the relative concentrations of O2, ADP, and protein. 4) The free energy of electron flow is not only used for the enzymatic binding and release of substrates and products but fundamentally for the actual synthesis of ATP from ADP and Pi. 5) The concentration of ADP that produces half-maximal responses of ATP synthesis (EC50) is not constant but varies depending on both DeltaE(h) and O2 concentration. 6) The process of ATP synthesis exhibits strong positive catalytic cooperativity with a Hill coefficient, n, of approximately 3.0. It is concluded that the most important factor in determining the extent and rates of ATP synthesis is not the level of ADP or the proton gradient but the concentration of O2 and the state of reduction and/or protonation of the membrane.

KEYWORDS:

Energy transduction; free energy of electron flow and ATP synthesis; proton gradient

PMID:
18566675
PMCID:
PMC2424179
[PubMed - indexed for MEDLINE]
Free PMC Article
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Ivyspring International Publisher Icon for PubMed Central
    Loading ...
    Support Center