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. 2016 Dec 29;45(4):1596–1605. doi: 10.1093/nar/gkw1305

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© The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact journals.permissions@oup.com

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Figure 1. — Depictions of Donnan equilibrium dialysis experiments used to measure the preferential ion interaction coefficient, Γ, under (A) idealized (molal) and (B) practical (molar) conditions. In both cases, an NA-containing solution is equilibrated with a bulk salt reservoir across a membrane permeable to ions but impermeable to the NA. In the toy example illustrated, the NA has −4 charge. This charge is neutralized by electrostatic (ES) interactions: three cations are drawn into the sample compartment () and one anion is displaced into the reservoir (). Under practical conditions, excluded volume (EV) displaces equal numbers of cations and anions across the membrane. In this case, one cation and one anion are displaced, leading to and .

Inline graphic — Depictions of Donnan equilibrium dialysis experiments used to measure the preferential ion interaction coefficient, Γ, under (A) idealized (molal) and (B) practical (molar) conditions. In both cases, an NA-containing solution is equilibrated with a bulk salt reservoir across a membrane permeable to ions but impermeable to the NA. In the toy example illustrated, the NA has −4 charge. This charge is neutralized by electrostatic (ES) interactions: three cations are drawn into the sample compartment () and one anion is displaced into the reservoir (). Under practical conditions, excluded volume (EV) displaces equal numbers of cations and anions across the membrane. In this case, one cation and one anion are displaced, leading to and .