A Quantum-mechanical description of ion motion within the confining potentials of voltage gated ion channels

TL;DR

This paper demonstrates that quantum mechanical effects are essential to understanding ion selectivity and gating kinetics in voltage-gated ion channels, highlighting the role of quantum delocalization of ions within protein filters.

Contribution

It provides the first quantum mechanical solutions for ion interactions within channel proteins, revealing ion delocalization effects at physiological temperatures.

Findings

Ions can become highly delocalized in the protein filter region.

Quantum properties influence ion selectivity and gating kinetics.

Ion kinetic energy depends on interactions and oscillation frequencies of surrounding groups.

Abstract

Voltage gated channel proteins cooperate in the transmission of membrane potentials between nerve cells. With the recent progress in atomic-scaled biological chemistry it has now become established that these channel proteins provide highly correlated atomic environments that may maintain electronic coherences even at warm temperatures. Here we demonstrate solutions of the Schr\"{o}dinger equation that represent the interaction of a single potassium ion within the surrounding carbonyl dipoles in the Berneche-Roux model of the bacterial \textit{KcsA} model channel. We show that, depending on the surrounding carbonyl derived potentials, alkali ions can become highly delocalized in the filter region of proteins at warm temperatures. We provide estimations about the temporal evolution of the kinetic energy of ions depending on their interaction with other ions, their location within the oxygen cage of the proteins filter region and depending on different oscillation frequencies of the surrounding carbonyl groups. Our results provide the first evidence that quantum mechanical properties are needed to explain a fundamental biological property such as ion-selectivity in trans-membrane ion-currents and the effect on gating kinetics and shaping of classical conductances in electrically excitable cells.