PH-SENSITIVE, CATION-SELECTIVE CHANNELS FORMED BY A SIMPLE SYNTHETIC POLYELECTROLYTE IN ARTIFICIAL BILAYER-MEMBRANES

A synthetic amphiphilic polymer, poly(2-ethylacrylic acid), induces po re formation in artificial phospholipid bilayers under mildly acidic c onditions. This process is pH-controllable and produces cation-selecti ve ion channels of at least three unique large conductances with diffe ring Na+/Cl- permeability ratio values. Two general types of channel g ating kinetics are observed, one flickering and irregular and one regu lar and discrete. The discrete channel activity resembles that of well -characterized biological and synthetic peptides. Given the heterogene ity of polymer structure and conformation, this observation raises que stions about the mechanism of polymer channel formation and the nature of these channels in lipid bilayer membranes.