[A new phenomenon induced by ion conformational interaction in biomembrane channels]

In several experimental studies it has been observed that when the ion flow approaches zero one of the conduction sublevels disappears irrespective of how the controlling parameters are changed. It is explained by the fact that the bistable regime in the ion channel appears only when the difference of the electrochemical potentials exceeds the threshold level, and such systems can function only in strongly now-equilibrium conditions. We describe the conformational mobility of the ion channel structure in terms of stochastic differential equations. It allows us to study behaviour of the ion channel, that is, volt-ampere characteristics, and kinetic parameters such as the lifetime and probability of the open state, ect. Ion-conformational interaction is taken into account based on experimental data. It is demonstrated that in some cases this interaction plays a decisive role in functioning of ion channels, since it is what causes emergence of discrete conduction levels. Such channels are described in the frame of the synergistic approach, which is characterised by the monostable regime of functioning near the equilibrium state, whereas bistability is possible only when the ion flow exceeds the threshold value.