Dr. Lehninger died on 4th March 1986 after a lengthy illness.
The upper and lower limits of the mechanistic stoichiometry of mitochondrial oxidative phosphorylation
Stoichiometry of oxidative phosphorylation
Article first published online: 3 MAR 2005
European Journal of Biochemistry
Volume 158, Issue 2, pages 315–322, July 1986
How to Cite
BEAVIS, A. D. and LEHNINGER, A. L. (1986), The upper and lower limits of the mechanistic stoichiometry of mitochondrial oxidative phosphorylation. European Journal of Biochemistry, 158: 315–322. doi: 10.1111/j.1432-1033.1986.tb09753.x
- Issue published online: 3 MAR 2005
- Article first published online: 3 MAR 2005
- (Received March 13, 1986) – EJB 86 0259
Determination of the intrinsic or mechanistic P/O ratio of oxidative phosphorylation is difficult because of the unknown magnitude of leak fluxes. Applying a new approach developed to overcome this problem (see our preceding paper in this journal), the relationships between the rate of O2 uptake [(JO)3], the net rate of phosphorylation (JP), the P/O ratio, and the respiratory control ratio (RCR) have been determined in rat liver mitochondria when the rate of phosphorylation was systematically varied by three specific means. (a) When phosphorylation is titrated with carboxyatractyloside, linear relationships are observed between JP and (JO)3. These data indicate that the upper limit of the mechanistic P/O ratio is 1.80 for succinate and 2.90 for 3-hydroxybutyrate oxidation. (b) Titration with malonate or antimycin yields linear relationships between JP and (JO)3. These data give the lower limit of the mechanistic P/O ratio of 1.63 for succinate and 2.66 for 3-hydroxybutyrate oxidation. (c) Titration with a protonophore yields linear relationships between JP, (JO)3, and (JO)4 and between P/O and 1/RCR. Extrapolation of the P/O ratio to 1/RCR = 0 yields P/O ratios of 1.75 for succinate and 2.73 for 3-hydroxybutyrate oxidation which must be equal to or greater than the mechanistic stoichiometry. When published values for the H+/O and H+/ATP ejection ratios are taken into consideration, these measurements suggest that the mechanistic P/O ratio is 1.75 for succinate oxidation and 2.75 for NADH oxidation.