Bal 2012 PLOS ONE: Difference between revisions

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Bal W, Kurowska E, Maret W (2012) The final frontier of pH and the undiscovered country beyond. PLOS ONE 7(9):e45832.

» https://doi.org/10.1371/journal.pone.0045832

Bal W, Kurowska E, Maret W (2012) PLOS ONE

Abstract: The comparison of volumes of cells and subcellular structures with the pH values reported for them leads to a conflict with the definition of the pH scale. The pH scale is based on the ionic product of water, K_w = [H⁺]×[OH⁻]. We used K_w [in a reversed way] to calculate the number of undissociated H₂O molecules required by this equilibrium constant to yield at least one of its daughter ions, H⁺ or OH⁻ at a given pH. In this way we obtained a formula that relates pH to the minimal volume V_pH required to provide a physical meaning to K_w, (where N_A is Avogadro’s number). For example, at pH 7 (neutral at 25 °C) V_pH = 16.6 aL. Any deviation from neutral pH results in a larger V_pH value. Our results indicate that many subcellular structures, including coated vesicles and lysosomes, are too small to contain free H⁺ ions at equilibrium, thus the definition of pH based on K_w is no longer valid. Larger subcellular structures, such as mitochondria, apparently contain only a few free H⁺ ions. These results indicate that pH fails to describe intracellular conditions, and that water appears to be dissociated too weakly to provide free H⁺ ions as a general source for biochemical reactions. Consequences of this finding are discussed.

• Bioblast editor: Gnaiger E

Cited by

Gnaiger E (2020) Mitochondrial pathways and respiratory control. An introduction to OXPHOS analysis. 5^th ed. Bioenerg Commun 2020.2. https://doi.org/10.26124/bec:2020-0002

Labels:

Preparation: Isolated mitochondria

Regulation: pH

BEC 2020.2

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 |year=2012
 |journal=PLOS ONE
-|abstract=The comparison of volumes of cells and subcellular structures with the pH values reported for them leads to a conflict with the definition of the pH scale. The pH scale is based on the ionic product of water, Kw = [H+]×[OH−]. We used Kw [in a reversed way] to calculate the number of undissociated H2O molecules required by this equilibrium constant to yield at least one of its daughter ions, H+ or OH− at a given pH. In this way we obtained a formula that relates pH to the minimal volume VpH required to provide a physical meaning to Kw, (where NA is Avogadro’s number). For example, at pH 7 (neutral at 25 °C) VpH = 16.6 aL. Any deviation from neutral pH results in a larger VpH value. Our results indicate that many subcellular structures, including coated vesicles and lysosomes, are too small to contain free H+ ions at equilibrium, thus the definition of pH based on Kw is no longer valid. Larger subcellular structures, such as mitochondria, apparently contain only a few free H+ ions. These results indicate that pH fails to describe intracellular conditions, and that water appears to be dissociated too weakly to provide free H+ ions as a general source for biochemical reactions. Consequences of this finding are discussed.
+|abstract=The comparison of volumes of cells and subcellular structures with the pH values reported for them leads to a conflict with the definition of the pH scale. The pH scale is based on the ionic product of water, ''K''<sub>w</sub> = [H<sup>+</sup>]×[OH<sup>−</sup>]. We used ''K''<sub>w</sub> [in a reversed way] to calculate the number of undissociated H<sub>2</sub>O molecules required by this equilibrium constant to yield at least one of its daughter ions, H<sup>+</sup> or OH<sup>−</sup> at a given pH. In this way we obtained a formula that relates pH to the minimal volume ''V''<sub>pH</sub> required to provide a physical meaning to ''K''<sub>w</sub>, (where ''N''<sub>A</sub> is Avogadro’s number). For example, at pH 7 (neutral at 25 °C) ''V''<sub>pH</sub> = 16.6 aL. Any deviation from neutral pH results in a larger ''V''<sub>pH</sub> value. Our results indicate that many subcellular structures, including coated vesicles and lysosomes, are too small to contain free H<sup>+</sup> ions at equilibrium, thus the definition of pH based on ''K''<sub>w</sub> is no longer valid. Larger subcellular structures, such as mitochondria, apparently contain only a few free H<sup>+</sup> ions. These results indicate that pH fails to describe intracellular conditions, and that water appears to be dissociated too weakly to provide free H<sup>+</sup> ions as a general source for biochemical reactions. Consequences of this finding are discussed.
 |editor=Gnaiger E
 }}
+== Cited by ==
+{{Template:Cited by Gnaiger 2020 BEC MitoPathways}}
 {{Labeling
 |preparations=Isolated mitochondria
 |topics=pH
+|additional=BEC 2020.2
 }}