AP1 (GEQGALAQFGEWL) was shown by theoretical analysis to be an anionic oblique-orientateda-helix former. The peptide exhibited a mono-layer surface area of nm 2 , implying possession of a-helical structure at an air⁄water interface, and Fourier transform infrared spectroscopy (FTIR) showed the peptide to be a-helical (100%) in the presence of vesi-cle mimics of Escherichia colimembranes.