Talk:Protonmotive force: Difference between revisions
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== Picked up == | |||
::::* https://arxiv.org/ftp/arxiv/papers/1703/1703.05826.pdf | ::::* https://arxiv.org/ftp/arxiv/papers/1703/1703.05826.pdf | ||
== In prep: The Blue Book 2019 == | |||
[[Gnaiger E]] 2019-09-05 | |||
=== Section 8.3.6. Moles and numbers === | |||
:::: Why should we consider in addition to the molar format of chemistry the particle or molecular format of quantum and statistical mechanics in mitochondrial physiology? At a mt-matrix pH 8, the proton activity is 10<sup>-8</sup> corresponding to a concentration of free protons of 0.01 ยตmolโL<sup>-1</sup> (6โ10<sup>15</sup> H<sup>+</sup>โL<sup>-1</sup>). For a mt-matrix volume of 0.3 ยตm<sup>3</sup>โmtยญ<sup>-1</sup> (Schwertzmann et al 1986; 3โ10<sup>-16</sup> Lโmt<sup>-1</sup>) the molar amount of protons is 3โ10<sup>-24</sup> molโmtยญ<sup>-1</sup>. Multiplied by the Avogadro constant (6โ10<sup>23</sup> xโmol<sup>-1</sup>), the number of protons per mitochondrion is โผ2 H<sup>+</sup>โmt<sup>-1</sup>. A similar result of 6 H<sup>+</sup>โmt<sup>-1</sup> is obtained with reference to a mt-matrix volume per mt-protein of 1 ยตLโmg<sup>-1</sup> and 10<sup>9</sup> mtโmg<sup>-1</sup> protein. Thus we can expect only a few protons in a single mitochondrion on average at any point of time. This should be given more thought in the discussion of fluctuations and mitochondrial heterogeneity, particularly in single cell analysis with typically 300 mitochondria per cell. Animated cartoons on the electron transfer system with too many bouncing protons propagate a false image. | |||
:::: When adding a mt-concentration of 0.1 mg protein per mL to a respirometric chamber with a mt-matrix volume, ''V''<sub>mt</sub>, of 10<sup>-6</sup> Lโmg<sup>-1</sup> protein, the volume fraction is ''V''<sub>mt</sub>/''V''=0.0001 or 0.1 ยตLโmL<sup>-1</sup>. At pH 8, 0.1 ยตL mitochondrial matrix contain 10<sup>-15</sup> mol H<sup>+</sup> equivalent to 6โ10<sup>8</sup> protons. Thus statistically relevant information can be obtained on the protonmotive force when using large numbers of mitochondria even at high dilution in a respirometric chamber of 2 mL, containing >1 billion H<sup>+</sup> in the mt-matrix. Thermodynamic terms such as temperature, Gibbs energy, pH and the ''pmF'' can be defined only on the basis of large numbers. |
Revision as of 10:56, 5 September 2019
Picked up
In prep: The Blue Book 2019
Gnaiger E 2019-09-05
Section 8.3.6. Moles and numbers
- Why should we consider in addition to the molar format of chemistry the particle or molecular format of quantum and statistical mechanics in mitochondrial physiology? At a mt-matrix pH 8, the proton activity is 10-8 corresponding to a concentration of free protons of 0.01 ยตmolโL-1 (6โ1015 H+โL-1). For a mt-matrix volume of 0.3 ยตm3โmtยญ-1 (Schwertzmann et al 1986; 3โ10-16 Lโmt-1) the molar amount of protons is 3โ10-24 molโmtยญ-1. Multiplied by the Avogadro constant (6โ1023 xโmol-1), the number of protons per mitochondrion is โผ2 H+โmt-1. A similar result of 6 H+โmt-1 is obtained with reference to a mt-matrix volume per mt-protein of 1 ยตLโmg-1 and 109 mtโmg-1 protein. Thus we can expect only a few protons in a single mitochondrion on average at any point of time. This should be given more thought in the discussion of fluctuations and mitochondrial heterogeneity, particularly in single cell analysis with typically 300 mitochondria per cell. Animated cartoons on the electron transfer system with too many bouncing protons propagate a false image.
- When adding a mt-concentration of 0.1 mg protein per mL to a respirometric chamber with a mt-matrix volume, Vmt, of 10-6 Lโmg-1 protein, the volume fraction is Vmt/V=0.0001 or 0.1 ยตLโmL-1. At pH 8, 0.1 ยตL mitochondrial matrix contain 10-15 mol H+ equivalent to 6โ108 protons. Thus statistically relevant information can be obtained on the protonmotive force when using large numbers of mitochondria even at high dilution in a respirometric chamber of 2 mL, containing >1 billion H+ in the mt-matrix. Thermodynamic terms such as temperature, Gibbs energy, pH and the pmF can be defined only on the basis of large numbers.