Fluorescence emission spectra were measured between 460?600 nm on a Perkin-Elmer luminescence spectrometer with a scan speed of 140 nm/min. An excitation wavelength of 480 nm and a quartz cuvette with an optical pathwidth of 4 mm was used. The excitation and emission slit-widths were set to 4 nm. Experiments were performed at 25 °C. The initial fluorescence signal, Fo (when vesicles are intact, i.e., no leakage), was measured and each run was started by the addition of 50 µL of a peptide solution. Fluorescence spectra were measured every minute for 20 min before the addition of 10% Triton X-100 solution, whereby the vesicles are completely perturbed giving rise to the formation of mixed micelles and yielding a fluorescence signal of maximum intensity, Fx. Control experiments were conducted with the addition of MilliQ H2O only.