VISUALIZATION OF PROTEIN PENETRATION FROM AN AQUEOUS SUBPHASE INTO A LANGMUIR MONOLAYER OF L-ALPHA-DIOLEOYLLECITHIN BY A NEW REPLICA METHOD FOR ELECTRON-MICROSCOPY WITH PLASMA POLYMERIZED FILM BY GLOW-DISCHARGE

Penetration of staphylococcal alpha-toxin from an aqueous subphase into a Langmuir monolayer of L-alpha-dioleoyllecithin at an air-water interface was studied by a new replica method for immunoelectron microscopy with plasma-initiated polymerized film. A lipid monolayer was prepared on an aqueous subphase containing alpha-toxin and the monolayer was deposited onto a glass plate. The monolayer-coated glass plate was treated with anti-alpha-toxin immunoglobulin G and then with protein A-gold in order to mark the toxin molecules, which might penetrate into the lipid monolayer, with gold particles of 10 nm diameter. A replica film of the thus treated monolayer surface was prepared by the replica method for transmission electron microscopy recently developed. Numerous gold particles were visualized in its replica image indicating that alpha-toxin molecules were able to penetrate into the lipid monolayer prepared on an aqueous subphase with the toxin.