[Artificial models of transport proteins in membrane]

Artificial molecules were designed to mimic membrane transport proteins which produce large and selective ion fluxes across biological membrane with functions of flux-control. Several amphiphilic lipid molecules were assembled in bilayer lipids to make supramolecular ion channels which gave single ion channel currents across planar lipid bilayers. Stable and constant conductance levels were observed with transitions between open and closed states. Unimolecular channels were also designed by using macrocyclic resorcinol tetramer, calix [6] arene or cyclodextrin. These unimolecular channels gave a single conductance and a sharp ion selectivity. All these channels were cation selective over anion. Ionic currents was successfully modulated by the application of membrane potential or photochemical isomerization.