Monte Carlo study of the effect of ion and channel size on the selectivity of a model calcium channel

Dezsö Boda, Douglas Henderson, David D. Busath

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Our earlier simulation (J. Phys. Chem. B 2000, 104, 8903) of the selectivity of a model calcium channel, where all ions were assumed to have the same diameter and the channel dimensions were fixed, is extended to allow for different ionic size and variable channel size. We find that for equal valence, the channel selects cations of the smallest size. If higher valence cations are present, the channel selects cations with the highest valence, and as a result, Ca++ will replace monovalent cations. This replacement is more efficient for larger monovalent cations than for smaller ones. This is what would be expected on the basis of the charge/space competition mechanism that has been postulated earlier. Of course, if the size ratio is very large, size might be selected over valence. In addition, we consider the effect of the channel diameter and find that narrow channels are less Ca++ selective. This suggests that the recent theory of Nonner et al. (Biophys. J. 2000, 79, 1976) is most useful for wide, but still microscopic, channels.

Original languageEnglish
Pages (from-to)11574-11577
Number of pages4
JournalJournal of Physical Chemistry B
Issue number47
Publication statusPublished - Nov 29 2001


ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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