scholarly journals Proton translocation quotient for the adenosine triphosphatase of rat liver mitochondria

FEBS Letters ◽  
1973 ◽  
Vol 30 (3) ◽  
pp. 317-320 ◽  
Author(s):  
Jennifer Moyle ◽  
Peter Mitchell
Keyword(s):  
Rat Liver ◽  
Adenosine Triphosphatase ◽  
Proton Translocation ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria

scholarly journals Proton translocation by the mitochondrial cytochrome b-c1 complex is inhibited by NN′-dicyclohexylcarbodi-imide

1982 ◽  
Vol 206 (2) ◽  
pp. 419-421 ◽  
Author(s):  
B D Price ◽  
M D Brand
Keyword(s):  
Electron Transport ◽  
Cytochrome Oxidase ◽  
Cytochrome B ◽  
Rat Liver ◽  
Proton Translocation ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Mitochondrial Cytochrome ◽  
Low Concentrations ◽  
Mitochondrial Cytochrome B

NN'-Dicyclohexylcarbodi-imide at low concentrations decreases the H+/2e ratio for rat liver mitochondria over the span succinate to oxygen from 5.9 +/- 0.3 (mean +/- S.E.M.) to 4.0 +/- 0.1 and for the cytochrome b-c1 complex from 3.8 +/- 0.2 to 1.9 +/- 0.1, but has little effect on the H+/2e ratio of cytochrome oxidase. The decrease in stoicheiometry is due, not to uncoupling or inhibition of electron transport, but to inhibition of proton translocation. NN'-Dicyclohexylcarbodi-imide thus ‘decouples’ proton translocation in the cytochrome b-c1 complex.

scholarly journals Factors affecting the translocation of oxaloacetate and l-malate into rat liver mitochondria

1968 ◽  
Vol 109 (5) ◽  
pp. 921-928 ◽  
Author(s):  
J. M. Haslam ◽  
D. E. Griffiths
Keyword(s):  
Rat Liver ◽  
Adenosine Triphosphatase ◽  
Liver Mitochondria ◽  
Spectrophotometric Assay ◽  
Rat Liver Mitochondria ◽  
Anaerobic Conditions ◽  
Factors Affecting ◽  
Adenosine Triphosphatase Activity ◽  
Energy Dependent ◽  
Stimulation Of

1. The rates of translocation of oxaloacetate and l-malate into rat liver mitochondria were measured by a direct spectrophotometric assay. 2. Penetration obeyed Michaelis–Menten kinetics, and apparent Km values were 40μm for oxaloacetate and 0·13mm for l-malate. 3. Arrhenius plots of the temperature-dependence of rates of penetration gave activation energies of +10kcal./mole for oxaloacetate and +8kcal./mole for l-malate. 4. The translocation of both oxaloacetate and l-malate was competitively inhibited by d-malate, succinate, malonate, meso-tartrate, maleate and citraconate. The Ki values of these inhibitors were similar for the penetration of both oxaloacetate and l-malate. 5. Rates of penetration were stimulated by NNN′N′-tetramethyl-p-phenylenediamine dihydrochloride plus ascorbate under aerobic conditions or by ATP under anaerobic conditions. 6. The energy-dependent stimulation of translocation was abolished by uncouplers of oxidative phosphorylation. Oligomycin A, aurovertin, octyl-guanidine and atractyloside prevented the stimulation by ATP, but did not inhibit the stimulation by NNN′N′-tetramethyl-p-phenylenediamine dihydrochloride plus ascorbate. 7. Mitochondria prepared in the presence of ethylene-dioxybis(ethyleneamino)tetra-acetic acid did not exhibit the energy-dependent translocation, but this could be restored by the addition of 50μm-calcium chloride. 8. Valinomycin or gramicidin plus potassium chloride enhanced the energy-dependent translocation of oxaloacetate and l-malate. 9. Addition of oxaloacetate stimulated the adenosine triphosphatase activity of the mitochondria, and the ratio of ‘extra’ oxaloacetate translocation to ‘extra’ adenosine triphosphatase activity was 1·6:1. 10. Possible mechanisms for the energy-dependent entry of oxaloacetate and l-malate into mitochondria are discussed in relation to the above results.

scholarly journals Effect of 2-n-heptyl-4-hydroxyquinoline N-oxide on proton permeability of the mitochondrial membrane

1980 ◽  
Vol 186 (2) ◽  
pp. 637-639 ◽  
Author(s):  
K Krab ◽  
M Wikström
Keyword(s):  
Respiratory Chain ◽  
Rat Liver ◽  
Proton Transport ◽  
Mitochondrial Membrane ◽  
Proton Translocation ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Proton Permeability ◽  
Isolated Rat Liver ◽  
Isolated Rat

The respiratory-chain inhibitor 2-n-heptyl-4-hydroxyquinoline N-oxide catalyses transmembrane proton transport driven by a pH gradient in isolated rat liver mitochondria. This effect explains the apparent blockade of net proton translocation by this compound in mitochondria respiring with ferrocyanide as described by Papa, Lorusso, Guerrieri, Boffoli, Izzo & Capuano [(1977) in Bioenergetics of Membranes (Packer, Papageorgiu & Trebst, eds.), pp. 377-388, Elsevier/North-Holland, Amsterdam] and by Lorusso, Capuano, Boffoli, Stefanelli & Papa [(1979) Biochem. J. 182, 133-147].

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