Fluorescence and Electron Microscopic Study of Lectin-Polysaccharide and Immunochemical Aggregation at Phospholipid Langmuir-Blodgett Monolayers

The interaction of phospholipid monolayers with the proteins concanavalin A and IgG antibody was examined by film balance measurements and by fluorescence and electron microscopies. Concanavalin A affects the size of lipid domains through preferential arrangement at the boundary between ordered domains and fluid environment. The aggregated protein present in structures formed by bonding with dextran both alters the shapes of lipid domains and increases monolayer viscosity by participation in a network that interconnects domains. The uniform shape of the aggregates (about 40 nm in size) and regularity of interaggregate distances can be attributed to the effect of long-range electrostatic forces. Although less pronounced, similar results to the above were observed for antibody-antigen interactions.