Difference between revisions of "Gnaiger 2018 EBEC2018"
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|year=2018 | |year=2018 | ||
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|abstract=ā.. ''the sum of the '''electrical pressure difference''' and the '''osmotic pressure difference''' (i.e. the electrochemical potential difference) of protons''ā [1] links to non-ohmic flux-force relationships between proton leak and protonmotive force (pmf). This is experimentally established, has direct consequences on mitochondrial physiology, but is theoretically little understood. Here I distinguish pressure from potential differences (diffusion: Ī''Ī¼<sub>H</sub>+'' or Ī<sub>d</sub>''F''<sub>H</sub>+; electric: Ī''ĪØ'' or Ī<sub>el</sub>''F''), to explain non-ohmic flux-force relationships on the basis of four thermodynamic theorems. (1) Einsteinās diffusion equation explains the concentration gradient (d''c''/d''z'') in Fickās law as the product of chemical potential gradient (the vector force and resistance determine the velocity, ''v'', of a particle) and local concentration, ''c''. This yields the chemical pressure gradient (vanāt Hoff equation): d<sub>d</sub>Ī /dz = RTād''c''/d''z''. Flux is the product of ''v'' and ''c''; ''c'' varies with force. Therefore, flux-force relationships are non-linear. (2) The pmf is not a vector force; the gradient is replaced by a pressure difference, and local concentration by a distribution function or free activity, ''Ī±''. Flux is a function of ''Ī±'' and force, ''J''<sub>d</sub> = ''b''ā''Ī±''āĪ<sub>d</sub>''F''<sub>B</sub> = -''b''āĪ<sub>d</sub>Ī <sub>B</sub>. (3) At Ī<sub>el</sub>''F'' = -Ī<sub>d</sub>''F''<sub>H</sub>+, the diffusion pressure of protons, Ī<sub>d</sub>Ī <sub>H</sub>+ = ''RT''āĪ<sub>c</sub><sub>H</sub>+ [Pa=Jām<sup>-3</sup>] is balanced by electric pressure, maintained by counterions of H<sup>+</sup>. Diffusional and electric pressures are isomorphic, additive, and yield protonmotive pressure (pmp). (4) The dependence of proton leak on pmf varies with Ī<sub>el</sub>''F'' versus Ī<sub>d</sub>''F''<sub>H</sub>+, in agreement with experimental evidence. The flux-force relationship is concave at high mitochondrial volume fractions, but near-exponential at small mt-matrix volume ratios. Linear flux-pmp relationships imply a near-exponential dependence of the proton leak on the pmf. | |abstract=ā.. ''the sum of the '''electrical pressure difference''' and the '''osmotic pressure difference''' (i.e. the electrochemical potential difference) of protons''ā [1] links to non-ohmic flux-force relationships between proton leak and protonmotive force (pmf). This is experimentally established, has direct consequences on mitochondrial physiology, but is theoretically little understood [2,3]. Here I distinguish pressure from potential differences (diffusion: Ī''Ī¼<sub>H</sub>+'' or Ī<sub>d</sub>''F''<sub>H</sub>+; electric: Ī''ĪØ'' or Ī<sub>el</sub>''F''), to explain non-ohmic flux-'''[[force]]''' relationships on the basis of four thermodynamic theorems. (1) Einsteinās diffusion equation [4] explains the [[concentration]] gradient (d''c''/d''z'') in Fickās law as the product of chemical potential gradient (the vector force and resistance determine the velocity, ''v'', of a particle) and local concentration, ''c''. This yields the chemical [[pressure]] gradient (vanāt Hoff equation): d<sub>d</sub>Ī /dz = RTād''c''/d''z''. [[Flux]] [5] is the product of ''v'' and ''c''; ''c'' varies with force. Therefore, flux-force relationships are non-linear. (2) The pmf is not a vector force; the gradient is replaced by a pressure difference, and local concentration by a distribution function or free activity, ''Ī±''. Flux is a function of ''Ī±'' and force, ''J''<sub>d</sub> = ''b''ā''Ī±''āĪ<sub>d</sub>''F''<sub>B</sub> = -''b''āĪ<sub>d</sub>''Ī ''<sub>B</sub> [6]. (3) At Ī<sub>el</sub>''F'' = -Ī<sub>d</sub>''F''<sub>H</sub>+, the diffusion pressure of protons, Ī<sub>d</sub>''Ī ''<sub>H</sub>+ = ''RT''āĪ<sub>c</sub><sub>H</sub>+ [Pa=Jām<sup>-3</sup>] is balanced by electric pressure, maintained by counterions of H<sup>+</sup>. Diffusional and electric pressures are isomorphic, additive, and yield protonmotive pressure (pmp). (4) The dependence of [[proton leak]] on pmf varies with Ī<sub>el</sub>''F'' versus Ī<sub>d</sub>''F''<sub>H</sub>+, in agreement with experimental evidence. The flux-force relationship is concave at high mitochondrial volume fractions, but near-exponential at small mt-matrix volume ratios. Linear flux-pmp relationships imply a near-exponential dependence of the proton leak on the pmf. | ||
|editor= | |editor=[[Gnaiger E]] | ||
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::::::Innsbruck, Austria. - [email protected] | ::::::Innsbruck, Austria. - [email protected] | ||
== | == References == | ||
::::#Mitchell P (1966) Chemiosmotic coupling in oxidative and photosynthetic phosphorylation. Glynn Research, Bodmin | ::::# Mitchell P (1966) Chemiosmotic coupling in oxidative and photosynthetic phosphorylation. Glynn Research, Bodmin. Biochim Biophys Acta Bioenergetics 1807:1507-38. | ||
::::# Garlid KD, Beavis AD, Ratkje SK (1989) On the nature of ion leaks in energy-transducing membranes. Biochim Biophys Acta 976:109-20. - [[Garlid 1989 Biochim Biophys Acta |Ā»Bioblast linkĀ«]] | |||
::::# Beard DA (2005) A biophysical model of the mitochondrial respiratory system and oxidative phosphorylation. PLOS Comput Biol 1(4):e36. - [[Beard 2005 PLOS Comput Biol |Ā»Bioblast linkĀ«]] | |||
::::# Einstein A (1905) Ćber die von der molekularkinetischen Theorie der WƤrme geforderte Bewegung von in ruhenden FlĆ¼ssigkeiten suspendierten Teilchen. Ann Physik 4, XVII:549-60. - [[Einstein 1905 Ann Physik 549 |Ā»Bioblast linkĀ«]] | |||
::::# Gnaiger E (1993) Nonequilibrium thermodynamics of energy transformations. Pure Appl Chem 65:1983-2002. - [[Gnaiger_1993_Pure_Appl_Chem |Ā»Bioblast linkĀ«]] | |||
::::# Gnaiger E (1989) Mitochondrial respiratory control: energetics, kinetics and efficiency. In: Energy transformations in cells and organisms. Wieser W, Gnaiger E (eds), Thieme, Stuttgart:6-17. - [[Gnaiger_1989_Energy_Transformations |Ā»Bioblast linkĀ«]] |
Revision as of 03:27, 7 August 2018
The protonmotive force under pressure: an isomorphic analysis. |
Link: EBEC2018
Gnaiger E (2018)
Event: EBEC2018 Budapest HU
ā.. the sum of the electrical pressure difference and the osmotic pressure difference (i.e. the electrochemical potential difference) of protonsā [1] links to non-ohmic flux-force relationships between proton leak and protonmotive force (pmf). This is experimentally established, has direct consequences on mitochondrial physiology, but is theoretically little understood [2,3]. Here I distinguish pressure from potential differences (diffusion: ĪĪ¼H+ or ĪdFH+; electric: ĪĪØ or ĪelF), to explain non-ohmic flux-force relationships on the basis of four thermodynamic theorems. (1) Einsteinās diffusion equation [4] explains the concentration gradient (dc/dz) in Fickās law as the product of chemical potential gradient (the vector force and resistance determine the velocity, v, of a particle) and local concentration, c. This yields the chemical pressure gradient (vanāt Hoff equation): ddĪ /dz = RTādc/dz. Flux [5] is the product of v and c; c varies with force. Therefore, flux-force relationships are non-linear. (2) The pmf is not a vector force; the gradient is replaced by a pressure difference, and local concentration by a distribution function or free activity, Ī±. Flux is a function of Ī± and force, Jd = bāĪ±āĪdFB = -bāĪdĪ B [6]. (3) At ĪelF = -ĪdFH+, the diffusion pressure of protons, ĪdĪ H+ = RTāĪcH+ [Pa=Jām-3] is balanced by electric pressure, maintained by counterions of H+. Diffusional and electric pressures are isomorphic, additive, and yield protonmotive pressure (pmp). (4) The dependence of proton leak on pmf varies with ĪelF versus ĪdFH+, in agreement with experimental evidence. The flux-force relationship is concave at high mitochondrial volume fractions, but near-exponential at small mt-matrix volume ratios. Linear flux-pmp relationships imply a near-exponential dependence of the proton leak on the pmf.
ā¢ Bioblast editor: Gnaiger E
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Affiliations
- D. Swarovski Research Lab, Dept Visceral, Transplant Thoracic Surgery, Medical Univ Innsbruck
- Oroboros Instruments
- Innsbruck, Austria. - [email protected]
References
- Mitchell P (1966) Chemiosmotic coupling in oxidative and photosynthetic phosphorylation. Glynn Research, Bodmin. Biochim Biophys Acta Bioenergetics 1807:1507-38.
- Garlid KD, Beavis AD, Ratkje SK (1989) On the nature of ion leaks in energy-transducing membranes. Biochim Biophys Acta 976:109-20. - Ā»Bioblast linkĀ«
- Beard DA (2005) A biophysical model of the mitochondrial respiratory system and oxidative phosphorylation. PLOS Comput Biol 1(4):e36. - Ā»Bioblast linkĀ«
- Einstein A (1905) Ćber die von der molekularkinetischen Theorie der WƤrme geforderte Bewegung von in ruhenden FlĆ¼ssigkeiten suspendierten Teilchen. Ann Physik 4, XVII:549-60. - Ā»Bioblast linkĀ«
- Gnaiger E (1993) Nonequilibrium thermodynamics of energy transformations. Pure Appl Chem 65:1983-2002. - Ā»Bioblast linkĀ«
- Gnaiger E (1989) Mitochondrial respiratory control: energetics, kinetics and efficiency. In: Energy transformations in cells and organisms. Wieser W, Gnaiger E (eds), Thieme, Stuttgart:6-17. - Ā»Bioblast linkĀ«