Studies on sodium and hydrogen ion translocation through the F0 part of the sodium-translocating F1F0 ATPase from Propionigenium modestum: discovery of a membrane potential dependent step

Biochemistry ◽  
1992 ◽  
Vol 31 (50) ◽  
pp. 12665-12672 ◽  
Author(s):  
Claudia Kluge ◽  
Peter Dimroth
Keyword(s):  
Membrane Potential ◽  
Hydrogen Ion ◽  
F1f0 Atpase ◽  
Ion Translocation ◽  
Propionigenium Modestum

Energy-dependent H+ and K+ translocation by the reconstituted yeast plasma membrane ATPase

1984 ◽  
Vol 62 (9) ◽  
pp. 865-877 ◽  
Author(s):  
Antonio Villalobo
Keyword(s):  
Plasma Membrane ◽  
Membrane Potential ◽  
Atp Hydrolysis ◽  
Potassium Ion ◽  
Plasma Membrane Atpase ◽  
Atpase Inhibitor ◽  
Yeast Plasma Membrane ◽  
Ion Translocation ◽  
Membrane Atpase ◽  
Energy Dependent

A highly purified plasma membrane ATPase from the yeast Schizosaccharomyces pombe incorporated into liposomes was able to carry out translocation of H+ and K+ in the absence of the substrate ATP, when a membrane potential of appropriate polarity was applied. In the absence of ATP, the membrane potential induced K+ translocation was strongly inhibited by the ATPase inhibitor vanadate. [Formula: see text], but not [Formula: see text], stimulated the rate of ATP hydrolysis in the absence, but not in the presence, of the H+-conducting agent carbonylcyanide m-chlorophenylhydrazone. Sodium ion on either side of the membrane did not have any stimulatory effect. The potassium ion translocation driven by ATP hydrolysis appeared to have two different kinetic components. Although the ATP-dependent K+ transport strictly required the presence of a membrane potential, the rate of K+ translocation was not affected by a broad modulation of the degree of coupling (q) between ATP hydrolysis and the electrogenic H+ translocation. These experiments support the view that the yeast plasma membrane ATPase not only uses the membrane potential generated by the electrogenic H+ translocation, but also uses part of the free energy of the hydrolysis of ATP (ΔGP) to translocate potassium ion across the cytoplasmic cell membrane.

scholarly journals SOME CONSEQUENCES OF THE THEORY OF MEMBRANE EQUILIBRIA

1925 ◽  
Vol 9 (1) ◽  
pp. 97-109 ◽  
Author(s):  
David I. Hitchcock
Keyword(s):  
Membrane Potential ◽  
Osmotic Pressure ◽  
Ionization Constant ◽  
Weak Acid ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Weak Base ◽  
Acid Base ◽  
Hydrogen Ion Concentration ◽  
Pass Through

In applying Donnan's theory of membrane equilibria to systems where the non-diffusible ion is furnished by a weak acid, base, or ampholyte, certain new relations have been derived. Equations have been deduced which give the ion ratio and the apparent osmotic pressure as functions of the concentration and ionization constant of the weak electrolyte, and of the hydrogen ion concentration in its solution. The conditions for maximum values of these two properties have been formulated. It is pointed out that the progressive addition of acid to a system containing a non-diffusible weak base should not cause the value of the membrane potential to rise, pass through a maximum, and fall, but should only cause it to diminish. It is shown that the theory predicts slight differences in the effect of salts on the ion ratio in such systems, the effect increasing with the valence of the cation.

scholarly journals ON THE INFLUENCE OF AGGREGATES ON THE MEMBRANE POTENTIALS AND THE OSMOTIC PRESSURE OF PROTEIN SOLUTIONS

1922 ◽  
Vol 4 (6) ◽  
pp. 769-776 ◽  
Author(s):  
Jacques Loeb
Keyword(s):  
Membrane Potential ◽  
Hydrostatic Pressure ◽  
Osmotic Pressure ◽  
Membrane Potentials ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Gelatin Solution ◽  
True Solution ◽  
Hydrogen Ion Concentration ◽  
Donnan Equilibrium

1. It is shown that when part of the gelatin in a solution of gelatin chloride is replaced by particles of powdered gelatin (without change of pH) the membrane potential of the solution is influenced comparatively little. 2. A measurement of the hydrogen ion concentration of the gelatin chloride solution and the outside aqueous solution with which the gelatin solution is in osmotic equilibrium, shows that the membrane potential can be calculated from this difference of hydrogen ion concentration with an accuracy of half a millivolt. This proves that the membrane potential is due to the establishment of a membrane equilibrium and that the powdered particles participate in this membrane equilibrium. 3. It is shown that a Donnan equilibrium is established between powdered particles of gelatin chloride and not too strong a solution of gelatin chloride. This is due to the fact that the powdered gelatin particles may be considered as a solid solution of gelatin with a higher concentration than that of the weak gelatin solution in which they are suspended. It follows from the theory of membrane equilibria that this difference in concentration of protein ions must give rise to potential differences between the solid particles and the weaker gelatin solution. 4. The writer had shown previously that when the gelatin in a solution of gelatin chloride is replaced by powdered gelatin (without a change in pH), the osmotic pressure of the solution is lowered the more the more dissolved gelatin is replaced by powdered gelatin. It is therefore obvious that the powdered particles of gelatin do not participate in the osmotic pressure of the solution in spite of the fact that they participate in the establishment of the Donnan equilibrium and in the membrane potentials. 5. This paradoxical phenomenon finds its explanation in the fact that as a consequence of the participation of each particle in the Donnan equilibrium, a special osmotic pressure is set up in each individual particle of powdered gelatin which leads to a swelling of that particle, and this osmotic pressure is measured by the increase in the cohesion pressure of the powdered particles required to balance the osmotic pressure inside each particle. 6. In a mixture of protein in solution and powdered protein (or protein micellæ) we have therefore two kinds of osmotic pressure, the hydrostatic pressure of the protein which is in true solution, and the cohesion pressure of the aggregates. Since only the former is noticeable in the hydrostatic pressure which serves as a measure of the osmotic pressure of a solution, it is clear why the osmotic pressure of a protein solution must be diminished when part of the protein in true solution is replaced by aggregates.

Crucial role of the membrane potential for ATP synthesis by F(1)F(o) ATP synthases

2000 ◽  
Vol 203 (1) ◽  
pp. 51-59 ◽  
Author(s):  
P. Dimroth ◽  
G. Kaim ◽  
U. Matthey
Keyword(s):  
Membrane Potential ◽  
Atp Synthase ◽  
Atp Synthesis ◽  
Operating Conditions ◽  
Chloroplast Atp Synthase ◽  
Counter Rotation ◽  
Cell Energy ◽  
Propionigenium Modestum ◽  
Far From Equilibrium

ATP, the universal carrier of cell energy, is manufactured from ADP and phosphate by the enzyme ATP synthase using the free energy of an electrochemical gradient of protons (or Na(+)). The proton-motive force consists of two components, the transmembrane proton concentration gradient (delta pH) and the membrane potential. The two components were considered to be not only thermodynamically but also kinetically equivalent, since the chloroplast ATP synthase appeared to operate on delta pH only. Recent experiments demonstrate, however, that the chloroplast ATP synthase, like those of mitochondria and bacteria, requires a membrane potential for ATP synthesis. Hence, the membrane potential and proton gradient are not equivalent under normal operating conditions far from equilibrium. These conclusions are corroborated by the finding that only the membrane potential induces a rotary torque that drives the counter-rotation of the a and c subunits in the F(o) motor of Propionigenium modestum ATP synthase.

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