Self-optimized biological channels in facilitating the transmembrane movement of charged molecules

TL;DR

This paper models biological channels as self-optimized structures that enhance the transmembrane movement of charged molecules by resonating with their potential, showing selectivity and non-Ohmic conductance.

Contribution

It introduces a model demonstrating how biological channels self-optimally tune their potential to facilitate charged molecule transport via resonance effects.

Findings

Channels are self-optimized to match resonant potential for maximum current

Facilitation is intrinsic and independent of external voltage or concentration gradient

Conductance exhibits a resonance at the channel's optimal potential

Abstract

We consider an anisotropically two-dimensional diffusion of a charged molecule (particle) through a large biological channel under an external voltage. The channel is modeled as a cylinder of three structure parameters: radius, length, and surface density of negative charges located at the channel interior-lining. These charges induce inside the channel a potential that plays a key role in controlling the particle current through the channel. It was shown that to facilitate the transmembrane particle movement the channel should be reasonably self-optimized so that its potential coincides with the resonant one, resulting in a large particle current across the channel. Observed facilitation appears to be an intrinsic property of biological channels, regardless the external voltage or the particle concentration gradient. This facilitation is very selective in the sense that a channel of definite structure parameters can facilitate the transmembrane movement of only particles of proper valence at corresponding temperatures. Calculations also show that the modeled channel is non-Ohmic with the ion conductance which exhibits a resonance at the same channel potential as that identified in the current.