Transport threshold in a quantum model for the KscA ion channel

Abstract

The mechanism behind the high throughput rate in K⁺ channels is still an open problem. However, recent simulations have shown that the passage of potassium through the K⁺ channel core, the so-called selectivity filter, is water-free against models where the strength of Coulomb repulsion freezes ions conduction. Thus, it has been suggested that coherent quantum hopping might be relevant in mediating ion conduction. Within the quantum approach and the hypothesis of desolvated ions along the pathway, we start with several particles in a source to see how they go across a selectivity filter, modeled by a linear chain of sites, to be collected in a drain. We show that the average selectivity filter occupancy is three ions, and the ion transfer rate is ~ 10⁸ ions/s, results which agree with the recent findings in the literature.