Difference between revisions of "Brand 1976 Proc Natl Acad Sci USA"
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|journal=Proc Natl Acad Sci USA | |journal=Proc Natl Acad Sci USA | ||
|abstract=The number of protons ejected during electron transport per pair of electrons per energy-conserving site (the H<sup>+</sup>/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. | |abstract=The number of protons ejected during electron transport per pair of electrons per energy-conserving site (the H<sup>+</sup>/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. | ||
# In the Ca<sup>2+</sup> pulse method, between 3.5 and 4.0 molecules of 3-hydroxybutyrate and 1.75 to 2.0 Ca<sup>2+</sup> ions were accumulated per 2 e<sup>-</sup> per site during Ca<sup>2+</sup> 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<sup>+</sup>/site ratio of 3.5-4.0 | |||
# In the oxygen pulse method addition of known amounts of oxygen to anaerobic mitochondria in the presence of substrate yielded H<sup>+</sup>/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<sup>+</sup>/site ratio was 2.0. | |||
# In the reductant pulse method measurement of the initial steady rates of H<sup>+</sup> ejection and oxygen consumption by mitochondria in an aerobic medium after addition of substrate gave H<sup>+</sup>/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 | Abstract Continued in Free Text | ||
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|additional=Made history | |additional=Made history | ||
}} | }} | ||
:Abstract Cont. | :Abstract Cont. | ||
These and other experiments reported indicate that the values of 2.0 earlier obtained for the H<sup>+</sup>/site ratio by Mitchell and Moyle [''Biochem J. (1967) 105, 1147-1162''] and others were underestimates due to the unrecognized masking of H<sup>+</sup> ejection by movements of endogenous phosphate. The results presented here show that the H<sup>+</sup>/site ratio of mitochondrial electron transport is at least 3.0 and may be as high as 4.0. | These and other experiments reported indicate that the values of 2.0 earlier obtained for the H<sup>+</sup>/site ratio by Mitchell and Moyle [''Biochem J. (1967) 105, 1147-1162''] and others were underestimates due to the unrecognized masking of H<sup>+</sup> ejection by movements of endogenous phosphate. The results presented here show that the H<sup>+</sup>/site ratio of mitochondrial electron transport is at least 3.0 and may be as high as 4.0. |
Revision as of 21:11, 22 June 2012
Brand MD, Reynafarje B, Lehninger AL (1976) Stoichiometric relationship between energy-dependent proton ejection and electron transport in mitochondria. Proc Natl Acad Sci USA 73: 437-441 |
Brand MD, Reynafarje B, Lehninger AL (1976) Proc Natl Acad Sci USA
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.
- 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
- 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.
- 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:
Organism: Rat
Tissue;cell: Hepatocyte; Liver"Hepatocyte; Liver" is not in the list (Heart, Skeletal muscle, Nervous system, Liver, Kidney, Lung;gill, Islet cell;pancreas;thymus, Endothelial;epithelial;mesothelial cell, Blood cells, Fat, ...) of allowed values for the "Tissue and cell" property.
Preparation: Isolated Mitochondria"Isolated Mitochondria" is not in the list (Intact organism, Intact organ, Permeabilized cells, Permeabilized tissue, Homogenate, Isolated mitochondria, SMP, Chloroplasts, Enzyme, Oxidase;biochemical oxidation, ...) of allowed values for the "Preparation" property.
Regulation: Ion Homeostasis"Ion Homeostasis" is not in the list (Aerobic glycolysis, ADP, ATP, ATP production, AMP, Calcium, Coupling efficiency;uncoupling, Cyt c, Flux control, Inhibitor, ...) of allowed values for the "Respiration and regulation" property.
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.