Cookies help us deliver our services. By using our services, you agree to our use of cookies. More information

Brand 1976 Proc Natl Acad Sci USA

From Bioblast
Publications in the MiPMap
Brand MD, Reynafarje B, Lehninger AL (1976) Stoichiometric relationship between energy-dependent proton ejection and electron transport in mitochondria. Proc Natl Acad Sci U S A 73:437-41.

Β» PMID:1061146 Open Access

Brand MD, Reynafarje B, Lehninger AL (1976) Proc Natl Acad Sci U S A

Abstract: The number of protons ejected during electron transport per pair of electrons per energy-conserving site (the H+/site ratio) was measured in rat liver mitochondria by three different methods under conditions in which transmembrane movements of endogenous phosphate were minized or eliminated.

  1. In the Ca2+ pulse method, between 3.5 and 4.0 molecules of 3-hydroxybutyrate and 1.75 to 2.0 Ca2+ ions were accumulated per 2 e- per site during Ca2+ induced electron transport in the presence of rotenone, when measured under conditions in which movements of endogenous phosphate were negligible. Since entry of 3-hydroxybutyrate requires its protonation to the free acid these data correspond to an H+/site ratio of 3.5-4.0
  2. In the oxygen pulse method addition of known amounts of oxygen to anaerobic mitochondria in the presence of substrate yielded H+/site ratios of 3.0 when phosphate transport was eliminated by addition of N-ethylmaleimide or by anaerobic washing to remove endogenous phosphate. In the absence of such measures the observed H+/site ratio was 2.0.
  3. In the reductant pulse method measurement of the initial steady rates of H+ ejection and oxygen consumption by mitochondria in an aerobic medium after addition of substrate gave H+/site near 4.0 in the presence of N-ethylmaleimide; in the absence of the inhibitor the observed ratio was only 2.0.

Abstract Continued in Free Text β€’ Keywords: Energy-dependent proton ejection, Electron transport


Labels: MiParea: Respiration 


Organism: Rat  Tissue;cell: Liver  Preparation: Isolated mitochondria 

Regulation: Coupling efficiency;uncoupling, Ion;substrate transport, pH  Coupling state: OXPHOS 


Made history 

Abstract Cont.

These and other experiments reported indicate that the values of 2.0 earlier obtained for the H+/site ratio by Mitchell and Moyle [Biochem J. (1967) 105, 1147-1162] and others were underestimates due to the unrecognized masking of H+ ejection by movements of endogenous phosphate. The results presented here show that the H+/site ratio of mitochondrial electron transport is at least 3.0 and may be as high as 4.0.