Permeation as a Diffusion Process

The paper shows how the diffusive movement of ions through a channel protein can be described as a chemical reaction over an arbitrary shaped potential barrier. The result is simple and intuitive but without approximation beyond the electrodiffusion description of ion movement.

💡 Research Summary

The paper presents a rigorous reformulation of ion permeation through channel proteins as a diffusion‑driven chemical reaction, eliminating the need for the customary approximations that underlie classic electrodiffusion models such as the Goldman‑Hodgkin‑Katz (GHK) equation. Starting from the one‑dimensional Poisson‑Nernst‑Planck (PNP) description of ion flux, the authors retain the full spatial dependence of the electrostatic potential Φ(x) and do not assume a simple rectangular barrier. In steady state the current density J satisfies

 J = −D