Visualization of the morphology of purple membrane surfaces by monoclonal antibody techniques

A monoclonal antibody technique for determining the surface morphology of the purple membrane (PM) has been developed. Two types of antibodies for distinguishing the extracellular surface and the cytoplasmic surface of PM were produced by immunizing the corresponding synthetic peptides to mice. The Langmuir-Blodgett (LB) method was employed to form a single-layer two-dimensional array of PM fragments on an electron microscope grid. The LB film was then treated with the antibodies which had been labeled with colloidal gold particles. Electron microscope observations visualized the morphology of the two surfaces of PM to be rough and smooth regions, respectively; thus the orientation of PM fragments was determined.