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Ion channels are specific proteins present in the membranes of living cells. They control the flow of specific ions through a cell, initiated by an ion channel's electrochemical gradient. In doing so, they control important physiological…
Potassium (K-) channels catalyze K+ ion permeation across cellular membranes while simultaneously discriminating their permeation over Na+ ions by more than a factor of a thousand. Structural studies show bare K+ ions occupying the…
We use Brownian dynamics simulations to study the permeation properties of a generic electrostatic model of a biological ion channel as a function of the fixed charge $Q_f$ at its selectivity filter. We reconcile the recently-discovered…
With the ability to selectively control ionic flux, biological protein ion channels perform a fundamental role in many physiological processes. For practical applications that require the functionality of a biological ion channel, graphene…
The study of selection and gating in potassium channels is a very important issue in modern biology. Indeed such structures are known in all types of cells in all organisms where they play many important functional roles. The mechanism of…
Ion channels are proteins with holes down their middle that control the flow of ions and electric current across otherwise impermeable biological membranes. The flow of sodium, potassium, calcium (divalent), and chloride ions have been…
Ion channels play a key role in regulating cell behavior and in electrical signaling. In these settings, polar and charged functional groups -- as well as protein response -- compensate for dehydration in an ion-dependent way, giving rise…
Selective ion transport is a hallmark of biological ion channel behavior but is a major challenge to engineer into artificial membranes. Here, we demonstrate, with all-atom molecular dynamics simulations, that bare graphene nanopores yield…
Excitability is an attribute of life, and is a driving force in the descent of complexity. Cellular electrical activity as realized by membrane proteins that act as either channels or transporters is the basis of excitability. Electrical…
ClC chloride channels possess a homodimeric structure in which each monomer contains an independent chloride ion pathway. ClC channel gating is regulated by chloride ion concentration, pH, and voltage. Based on structural and physiological…
Ion channels form pores across the lipid bilayer, selectively allowing inorganic ions to cross the membrane down their electrochemical gradient. While the study of ion desolvation free-energies have attracted much attention, the role of…
Membranes selective to ions of the same charge are increasingly sought for wastewater processing and valuable element recovery. However, while narrow channels are known to be essential, other membrane parameters remain difficult to identify…
A simple theory of ion permeation through a channel is presented, in which diffusion occurs according to Fick's law and drift according to Ohm's law, in the electric field determined by all the charges present. This theory accounts for…
Ion transport through charged nanopores is commonly interpreted in terms of electrical double layer structure, leading to the expectation of cation-selective conduction in negatively charged pores. This picture can break down for…
A simple pillbox model with two adjustable parameters accounts for the selectivity of both DEEA Ca channels and DEKA Na channels in many ionic solutions of different composition and concentration. Only the side chains are different in the…
A discrete electrostatic/diffusion model has been developed to describe the selective permeation of ion channels, based on ionic Coulomb blockade (ICB) and quantised dehydration (QD). It has been applied to describe selectivity phenomena…
We report an experimental study of the influences of the fixed charge and bulk ionic concentrations on the conduction of biological ion channels, and we consider the results within the framework of the ionic Coulomb blockade model of…
A hydrophobic constriction site can act as an efficient barrier to ion and water permeation if its diameter is less than the diameter of an ion's first hydration shell. This hydrophobic gating mechanism is thought to operate in a number of…
Potassium channels play critical roles in many physiological processes, providing a selective permeation route for K+ ions in and out of a cell, by employing a carefully designed selectivity filter, evolutionarily conserved from viruses to…
Ion-selective channels play a key role in physiological processes and are used in many technologies. While biological channels can efficiently separate same-charge ions with similar hydration shells, it remains a challenge to mimic such…