Activation kinetics of the incorporation of colicin Ia into an artificial membrane: A Markov or a fractal model?

Abstract

We have used synthetic membranes to incorporate colicin Ia into a planar lipid bilayer. Colicin Ia is produced by the bacterium Eischerida coli and is a protein former of voltage-dependent channels, whose opening or closing can be controlled by an electrical field. Details of the structure and mode of action of colicin Ia have been reported elsewhere [1–4]. The kenitics of transition between different conformational states of the ion channels can be studied in noise analysis experiments, in which the noise from the current passing through the channels is analysed [5,6] under voltage-clamp conditions. Over the part few years, ion channel kinetics has been studies widely and described using Markov, diffusion, fractal and related models [6–18], and treated as either a deterministic chaotic process or a stochastic process. Here we shall not describe each model rigorously (for this, the reader should consult the literature), but we shall present an experimental system that behaves as either a Markov or a fractal model, depending on the experimental conditions imposed.