Wet lipid-protein membranes imaged at submolecular resolution by atomic force microscopy

Abstract

We have employed an AFM to determine the structural properties of supported planar membranes and membrane-bound proteins in an aqueous environment. Images of an asymmetric Langmuir Blodgett film of a charged phospholipid show long range positional as well as orientational order; individual headgroups are resolved. In order to study biofunctional membranes we have employed a recently introduced technique that allows the controlled formation of planar lipid-protein membranes on solid supports from a vesicle suspension. Combining this technique with the AFM permits the nondestructive imaging of these models of cell membranes at molecular resolution under physiological conditions of ionic strength and temperature.