Kedem 1958 Biochim Biophys Acta
|Kedem O, Katchalsky A (1958) Thermodynamic analysis of the permeability of biological membranes to non-electrolytes. Biochim Biophys Acta 27:229-46.|
Abstract: The application of the conventional permeability equations to the study of biological membranes leads often to contradictions. It is shown that the equations generally used, based on two permeability coefficients—the solute permeability coefficient and the water permeability coefficient—are incompatible with the requirements of thermodynamics of irreversible processes.
The inconsistencies are removed by a thermodynamic treatment, following the approach of Staverman, which leads to a three coefficient system taking into account the interactions: solute-solvent, solute-membrane and solvent-membrane.
The equations derived here have been applied to various permeability measurements found in the literature, such as: the penetration of heavy water into animal cells, permeability of blood vessels, threshold concentration of plasmolysis and relaxation experiments with artificial membranes.
It is shown how the pertinent coefficients may be derived from the experimental data and how to choose suitable conditions in order to obtain all the required information on the permeability of the membranes.
The significance of these coefficients for the elucidation of membrane structure is pointed out.
• Bioblast editor: Gnaiger E
Force or pressure? - The linear flux-pressure law
- "For many decades the pressure-force confusion has blinded the most brilliant minds, reinforcing the expectation that Ohm’s linear flux-force law should apply to the hydrogen ion circuit and protonmotive force. .. Physicochemical principles explain the highly non-linear flux-force relation in the dependence of LEAK respiration on the pmF. The explanation is based on an extension of Fick’s law of diffusion and Einstein’s diffusion equation, representing protonmotive pressure ― isomorphic with mechanical pressure, hydrodynamic pressure, gas pressure, and osmotic pressure ― which collectively follow the generalized linear flux-pressure law."
- Gnaiger E (2020) Mitochondrial pathways and respiratory control. An introduction to OXPHOS analysis. 5th ed. Bioenerg Commun 2020.2. doi:10.26124/bec:2020-0002
- » pressure = force × free activity
- "The misleading name ‘mean of the concentrations of the solute in the two compartments’ (Kedem, Katchalski 1958) has been given to the term αX" (free activity).
- Gnaiger E (2020) Mitochondrial pathways and respiratory control. An introduction to OXPHOS analysis. 5th ed. Bioenerg Commun 2020.2:112 pp. doi:10.26124/bec:2020-0002