PROTEIN-BINDING TO SUPPORTED LIPID-MEMBRANES - INVESTIGATION OF THE CHOLERA-TOXIN GANGLIOSIDE INTERACTION BY SIMULTANEOUS IMPEDANCE SPECTROSCOPY AND SURFACE-PLASMON RESONANCE

The specific recognition reaction between cholera toxin (ChTo) and the ganglioside G(M1) was investigated in situ on planar supported lipid layers using simultaneous surface plasmon resonance (SPR) and electroc hemical impedance measurements. The lipid monolayers containing differ ent amounts of G(M1) were formed on alkanethiol-coated gold surfaces b y a new lipid/detergent dilution technique. The formation of the layer s was investigated using both SPR and impedance measurements. While th e optical properties of the different lipid layers remained unchanged, the layer capacitance was seen to depend on the G(M1) to POPC molar r atio. The selective binding of ChTo to these layers was detected with high sensitivity by SPR. The comparatively small impedance changes ass ociated with the protein adsorption suggest a high water content of th e ChTo layers. The B5 subunit has been shown to interact similarly wit h these supported lipid layers.