Formation and Utilization of Stable Lipid Membranes with Multiple Resistance States - Gating Processes in Stabilized Lipid Membranes

摘要

Stabilized thin lipid membranes (TLM), with lipid bilayer properties, can be produced by incorporating polymers into the usual lipid solutions for generating TLM. In addition to increase mechanical and electrical strength, the lipid-polymer TLM has a striking capacity for self repair of punctures caused by excessive potential gradients. This property creates a novel gating mechanism for non-linear conductances under certain conditions. Similar self-repair can be obtained in composite membranes prepared by depositing lipid solutions in micropores of a very thin film, prepared from polyamides. Gating agents that are effective in normal bilayer membranes are also active in the stabilized TLM and composite membrane. Studies on the EIM gating mechanism showed that the unit channel exists in several discrete conductance levels. Alamethicin conductance develops in irregular bursts of increasing size and frequency with rising potential gradients, suggesting induction of transient channels with cooperative clustering of open units. A chemically sensitive allosteric gate (conductance modified by interaction of substrate with membrane-adsorbed enzymes) has been observed under some conditions with lipid bilayer membranes or associated structures. (Author Modified Abstract)