Key result
Dynamic Monte Carlo simulations showed that the binding affinity of Ca2+ versus Na+ is always larger than the dynamical selectivity due to tight binding and lower mobility in the selectivity filter.
This computational study demonstrates that in a model calcium channel, the binding affinity of Ca2+ over Na+ exceeds its dynamical selectivity due to reduced ion mobility at the binding site.
Should not guide clinical ion channel therapies; leaves open experimental validation of mobility effects in native channels.
We have performed dynamic Monte Carlo simulations for a model calcium channel and present our results in terms of binding affinity (expressed as the occupancy of the selectivity filter by various ions) and dynamical selectivity (expressed as the flux carried by various ions). We show that the binding affinity of Ca 2+ versus Na + is always larger than the dynamical selectivity because Ca 2+ ions are tightly bound to the binding site of the selectivity filter of the channel and, at the same time, their mobility and drift velocity is smaller in this region. We present density and drift velocity profiles of Ca 2+ and Na + in the channel for various mole fractions of Ca 2+ .
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Rutkai et al. (2010) studied this question. Dynamic Monte Carlo simulations was evaluated on Binding affinity and dynamical selectivity of Ca2+ versus Na+. Dynamic Monte Carlo simulations showed that the binding affinity of Ca2+ versus Na+ is always larger than the dynamical selectivity due to tight binding and lower mobility in the selectivity filter.
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