For the TR-SAXS experiments, the lipid membranes were incubated with peptide prior to the mea- surements, while the mixing with salts was done using a stopped-flow apparatus. The vesicle solution, with or without peptide, was loaded into the last reservoir of the stopped-flow apparatus. Two of the intermediate reservoirs were loaded with salt-free Tris, and 1.2 M NaCl solution, respectively. The first reservoir was loaded with pure MQ water and reserved for cleaning. Throughout the experiment, the same reservoirs were used for vesicles, buffer and salt solutions, respectively, to avoid cross contamination. Between vesicle loading, the specific chamber and exposure capillary were cleaned using a sequence of rinses with 2 % Hellmanex solution followed by MQ water, then ethanol and finally with MQ water again. It is also emphasized that the reservoirs and capillary were kept at the same temperature to avoid temperature shocks. Measurements were performed in the following order. First vesicle references were obtained by mixing the vesicle stock with Tris buffer. Then buffer measurements was obtained by mixing the salt-solution with Tris, and finally the vesicles were mixed with the salt-solution. Note that the first shot was discarded due to high probability of bubbles and, in all cases, the exact same mixing parameters and instrument settings (specifics presented below) were used. In the kinetic experiments, 1:20 PL ratio was used for indolicidin and aurein in addition to a lower 1:50 PL ratio for indolicidin. LL-37, on the other hand, is much more potent and known to solubilize the membrane at these ratios, so it was added in a significantly lower 1:100 PL ratio.