Assuming the selectivity filter of KcsA potassium ion channel may exhibit quantum coherence, we extend a previous model by Vaziri and Plenio (2010 New J. Phys. 12 085001) to take into account Coulomb repulsion between potassium ions. We show that typical ion transit timescales are determined by this interaction, which imposes optimal input/output parameter ranges. Also, as observed in other examples of quantum tunneling in biological systems, the addition of moderate noise helps coherent ion transport.

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 (SF), 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 SF, modeled by a linear chain of sites, to be collected in a drain. We show that the average SF occupancy is three ions, and the ion transfer rate is ∼108 ions s−1, results which agree with the recent findings in the literature.