Gnaiger 2018 EBEC2018: Difference between revisions
(Created page with "{{Abstract |title=The protonmotive force under pressure: an isomorphic analysis. |info=EBEC2018 |authors=Gnaiger E |year=2018 |event=EBEC2018 Budapest HU |abstract=β.. '...") Β |
No edit summary |
||
Line 5: | Line 5: | ||
|year=2018 | |year=2018 | ||
|event=EBEC2018 Budapest HU | |event=EBEC2018 Budapest HU | ||
|abstract=β.. ''the sum of the '''electrical pressure difference''' and the '''osmotic pressure difference''' (i.e. the electrochemical potential difference) of protons''β [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: Ξ''ΞΌ<sub>H</sub>+'' or Ξ<sub>d</sub>''F''<sub>H</sub>+; electric: Ξ''Ξ¨'' or Ξ<sub>el</sub>''F''), to explain non-ohmic flux-force relationships on the basis of four thermodynamic theorems. (1) Einsteinβs diffusion equation explains the concentration gradient (d''c''/d''z'') in Fickβs 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 (vanβt Hoff equation): d<sub>d</sub>Ξ / | |abstract=β.. ''the sum of the '''electrical pressure difference''' and the '''osmotic pressure difference''' (i.e. the electrochemical potential difference) of protons''β [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: Ξ''ΞΌ<sub>H</sub>+'' or Ξ<sub>d</sub>''F''<sub>H</sub>+; electric: Ξ''Ξ¨'' or Ξ<sub>el</sub>''F''), to explain non-ohmic flux-force relationships on the basis of four thermodynamic theorems. (1) Einsteinβs diffusion equation explains the concentration gradient (d''c''/d''z'') in Fickβs 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 (vanβt Hoff equation): d<sub>d</sub>Ξ /dz = RTβd''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, ''Ξ±''. Flux is a function of ''Ξ±'' and force, ''J''<sub>d</sub> = ''b''β''Ξ±''βΞ<sub>d</sub>''F''<sub>B</sub> = -''b''βΞ<sub>d</sub>Ξ <sub>B</sub>. (3) At Ξ<sub>el</sub>''F'' = -Ξ<sub>d</sub>''F''<sub>H</sub>+, the diffusion pressure of protons, Ξ<sub>d</sub>Ξ <sub>H</sub>+ = ''RT''βΞ<sub>c</sub><sub>H</sub>+ [Pa=Jβm<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 Ξ<sub>el</sub>''F'' versus Ξ<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=[[Kandolf G]], [[Gnaiger E]] | |editor=[[Kandolf G]], [[Gnaiger E]] | ||
}} | }} | ||
Line 13: | Line 13: | ||
::::#Oroboros Instruments | ::::#Oroboros Instruments | ||
::::::Innsbruck, Austria. - [email protected] | ::::::Innsbruck, Austria. - [email protected] | ||
== Reference == | |||
::::#Mitchell P (1966) Chemiosmotic coupling in oxidative and photosynthetic phosphorylation. Glynn Research, Bodmin, Biochim Biophys Acta Bioenergetics 1807:1507-38 |
Revision as of 08:27, 3 August 2018
The protonmotive force under pressure: an isomorphic analysis. |
Link: EBEC2018
Gnaiger E (2018)
Event: EBEC2018 Budapest HU
β.. the sum of the electrical pressure difference and the osmotic pressure difference (i.e. the electrochemical potential difference) of protonsβ [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: ΞΞΌH+ or ΞdFH+; electric: ΞΞ¨ or ΞelF), to explain non-ohmic flux-force relationships on the basis of four thermodynamic theorems. (1) Einsteinβs diffusion equation explains the concentration gradient (dc/dz) in Fickβs 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 (vanβt Hoff equation): ddΞ /dz = RTβdc/dz. 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, Ξ±. Flux is a function of Ξ± and force, Jd = bβΞ±βΞdFB = -bβΞdΞ B. (3) At ΞelF = -ΞdFH+, the diffusion pressure of protons, ΞdΞ H+ = RTβΞcH+ [Pa=Jβm-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 ΞelF versus ΞdFH+, 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.
β’ Bioblast editor: Kandolf G, Gnaiger E
Labels:
Affiliations
- D. Swarovski Research Lab, Dept Visceral, Transplant Thoracic Surgery, Medical Univ Innsbruck
- Oroboros Instruments
- Innsbruck, Austria. - [email protected]
Reference
- Mitchell P (1966) Chemiosmotic coupling in oxidative and photosynthetic phosphorylation. Glynn Research, Bodmin, Biochim Biophys Acta Bioenergetics 1807:1507-38