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. 2010 Sep;136(3):363-5.
doi: 10.1085/jgp.201010504.

A mesoscopic approach to understanding the mechanisms underlying the ion permeation on the discrete-state diagram

Shigetoshi Oiki, Masayuki Iwamoto, Takashi Sumikama

A mesoscopic approach to understanding the mechanisms underlying the ion permeation on the discrete-state diagram

Shigetoshi Oiki et al. J Gen Physiol. 2010 Sep.
No abstract available

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Figures

Figure 1.
Figure 1.
From ion permeation through channel structure to cycle kinetics on DSMM. The ion permeation processes (A) are projected on a discrete-state diagram (B) on which a random walk completing cyclic paths generates net ion flux. Macroscopic observables, such as the single-channel current, can be deduced with a set of rate constants for the diagram. These rate constants have been transformed to the free energy profile of ion permeation (C), and they can be used for calculating the mesoscopic parameter of the cycle flux. There are several cyclic paths on the diagram, some of which generate nonzero net flux (a and b) and others (c) do not (D). From the original diagram, all the cyclic paths were decomposed into one-way cyclic paths (D; right). All the one-way cycle fluxes can be calculated. Given the cycle fluxes, trends of random kinetic processes, such as relative contributions of the cycles, are visualized, and macroscopic observables were calculated using stoichiometric numbers (E). Permeation processes in different levels and experimental observables were related in the hierarchy of ion permeation events (F).
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