FIG. 4.

Possible orientations of MPER peptides and membrane proximity of tryptophan residues of MPER peptides. (A to C) Pictorial representations showing possible orientations that the MPER peptides could assume when conjugated to liposomes. (D) Schematic diagram showing the location of DANSYL label (star) in the lipid bilayer. The Forster distance (R₀) for observing 50% FRET efficiency for the DANSYL-tryptophan pair is indicated (32). (E to G) Tryptophan-to-DANSYL FRET for 2F5 nominal epitope (E), 4E10 nominal epitope (F), and biepitope (G) MPER peptide-liposome conjugates. In each panel, the solid curves show the fluorescence spectra of the peptide-liposome conjugates in the absence of DANSYL-PE, the dashed curves show the fluorescence spectra of peptide-liposome conjugates having 5mol% DANSYL-PE, and the dotted curves show the fluorescence of DANSYL-PE liposomes with no peptides.