Mitchell 1969 Eur J Biochem: Difference between revisions
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|topics=Coupling efficiency; uncoupling, Ion | |topics=Coupling efficiency; uncoupling, Ion&substrate transport, pH | ||
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Revision as of 10:54, 11 August 2013
Mitchell P, Moyle J (1969) Estimation of membrane potential and pH difference across the cristae membrane of rat liver mitochondria. Eur J Biochem 7: 471-484. |
Mitchell P, Moyle J (1969) Eur J Biochem
Abstract: The cristae membrane or M phase of resting or respiring rat liver mitochondria becomes relatively permeable to K+ ions in presence of valinomycin. The equilibrium distribution of K+ ions across the membrane can therefore be used to estimate the membrane potential ฮฮจ provided that precautions are taken to minimise swelling of the valinomycin-treated mitochondria. The pH difference ฮpH across the M phase of anaerobic mitochondria has been estimated from the buffering powers of the inner and outer phases and from the change of pH observed on lysing the mitochondria with Triton X-100. When the anaerobic mitochondria (State 5), in presence of ฮฒ-hydroxybutyrate, are brought to a state of steady respiration either in absence (State 4) or in presence (State 3) of phosphate acceptor, the changes of pH and of pK of the medium recorded with H+ ion-sensitive and K+ ion-sensitive electrodes can be used to estimate the changes of ฮฮจ and ฮpH across the M phase. The absolute values of ฮฮจ and ฮpH have been estimated from the values determined in State 5 and the change of these values in the transition from State 5 to States 4 and 3.
Continued in Free Text โข Keywords: membrane potential, pH difference, cristae membrane, valinomycin, K+ ions
Labels: MiParea: Respiration
Organism: Rat
Tissue;cell: Liver
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: Coupling efficiency; uncoupling"Coupling efficiency; uncoupling" 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., Ion&substrate transport"Ion&substrate transport" 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., pH
Made history
Abstract Continued
The total protonmotive force ฮp =ฮฮจโ 59 ฮpH across the M phase of the mitochondria oxidising ฮฒ-hydroxybutyrate in State 4 at 25ยฐ in a 250 mM sucrose medium near pH 7 is estimated to be about 230 mV, of which the major component is ฮฮจ when the effect of translocation of K+ ions across the M phase is minimised. Under conditions permitting accumulation of a relatively large quantity of cation (State 6), ฮp is not significantly different from that in State 4, but the major component is โZฮpH.
The effects of changing ฮp in mitochondrial suspensions in State 4 with uncoupling agent and with pulses of acid, alkali, calcium salt and ADP have been found to be in accord with the chemiosmotic hypothesis. In particular ฮp in State 3 (ADP and Pi present) is estimated to be about 30 mV less than in State 4.