The mitochondrial process of oxidative phosphorylation has usually been studied in I he presence of high concentrations of O2 by determining the extent and rates of O2 uptake and ATP synthesis. In this study, the time course of both O2 consumption and ATP synthesis are simultaneously determined in reactions initiated by adding O, to anaerobic suspensions of mitochondria in which the back flow of H' is at a minimum and the flow of electrons is opposed by zero resistance in the forms of AGP and A [iH'. The following novel characteristics of oxidative phosphorylation are found. I. ACip is a direct function of O2 concentration, regardless of protein and ADP concentration. 2. The reduction andor protonation of the entire membrane is crucial for the extremely rapid rates of ATP synthesis, 3. The initial steady-state rates of ATP synthesis are perfectly compatible with the very fast rates of O, consumption and net flow of electrons characteristic of the first phase of the respiratory process. 4. The initial rates of ATP synthesis, depend on the concentrations of either O2 or ADP strictly in accordance with the Michaelis-Meuten rate equation, provided the other 4 substrates of oxidative phosphorylation (H', e', Pi, and either ADP or O,) are maintained in excess. It is concluded that all catalytic sites in the F, moiety of the ATP synthase are kinetically equivalent in synthesizing ATP.
|Original language||English (US)|
|State||Published - 1997|
ASJC Scopus subject areas
- Agricultural and Biological Sciences (miscellaneous)
- Biochemistry, Genetics and Molecular Biology(all)
- Cell Biology