Ion coherence: A physical derivation of high-flux ion transport in biological channel

Abstract Biological ion channels usually conduct the high-flux transport of 107 to 108 ions/s, however the underlying mechanism is still lacking [1-7]. Here, applying the KcsA potassium channel as a typical sample, by multi-timescale molecular dynamics simulations, we demonstrate that there is coherence of K+ ions confined in biological channel, which determines the transport. Specifically, the coherent oscillation state of confined K+ ions with a nanosecond-level lifetime in the channel dominates each of transport events, serving as the physical basis of the high flux of ~108 ions/s. The coherent transfer of confined K+ ions, only taking several picoseconds and having no perturbation on the ion coherence, acts as the directional key of transport. The increase of ion coherence can significantly enhance the ion current by a coherence-induced transition. These findings provide a theoretical evidence supporting that the energy-efficient high-flux ion transport of biological channel is physically derived from ion coherence.