  Assuming that the selectivity filter of KcsA potassium ion channel may
exhibit quantum coherence, we extend a previous model by Vaziri and Plenio
(2010) 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, addition of moderate noise
helps coherent ion transport.
