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Ion channels are membrane proteins responsible for an enormous range of biological functions. Ion selectivity and permeation are based on simple laws of physics and chemistry. Ion channels are therefore ideal candidates for physical…
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…
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…
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…
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…
Potassium (K$^+$) channels regulate the flux of K$^+$ ions through cell membranes and plays significant roles in many physiological functions. This work studies the KcsA potassium channel, including the selectivity and current-voltage (IV)…
Orientation selectivity is the most striking feature of simple cell coding in V1 which has been shown to emerge from the reduction of higher-order correlations in natural images in a large variety of statistical image models. The most…
The S$_2$ site of the KcsA K$^+$ channel has eight carbonyl ligands in the ion-binding site. A recent study suggests that the K$^+$-over-Na$^+$ selectivity of the S$_2$ site can be understood by noting the larger free energy change involved…
Extensive molecular dynamics simulations of water permeation and ion selectivity of the single-walled carbon nanotubes with the radial deformation are presented . The simulated results indicate that there is a close relationship between the…
Ion channels are of major interest and form an area of intensive research in the fields of biophysics and medicine since they control many vital physiological functions. The aim of this work is on one hand to propose a fully stochastic and…
The energetics of ionic selectivity in the neuronal sodium channels is studied. A simple model constructed for the selectivity filter of the channel is used. The selectivity filter of this channel type contains aspartate (D), glutamate (E),…
The KcsA potassium channel belongs to a class of K+ channels that is selective for K+ over Na+ at rates of K+ transport approaching the diffusion limit. This selectivity is explained thermodynamically in terms of favorable partitioning of…
Many biological and artificial transport channels function without direct input of metabolic energy during a transport event and without structural rearrangements involving transitions from a 'closed' to an 'open' state. Nevertheless, such…
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…
Experiments on single ionic channels have contributed to a large extent to our current view on the function of cell membrane. In these experiments the main observables are the physical quantities: ionic concentration, membrane electrostatic…
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…
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…
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…
Electrostatic interactions involving proteins depend not just on the ionic charges involved but also on their chemical identities. Here we examine the origins of incompletely understood differences in the strength of association of…