It is important to note that changing the interior buffer contrast quite clearly is not sufficient for the peptide-free vesicles, as shown by the gray dashed lines in figures 2A and 2D. This is unsurprising, as these scattering curves deviate significantly from the regular vesicle scattering observed in the salt free case, indicating deformation. Hence, the resulting structures cannot be explained by a change in contrast. However, while the vesicles without peptide are clearly deformed, this deformation appears to be entirely related to the vesicle shape. The overall vesicle size remains unchanged as independently confirmed by DLS, with the details provided in the SI (Figure and Table ). It is interesing to note, however, that for the gel phase membranes (top curve in figures 2B and 2C) at the highest salt concentration a small deviation from the predicted scattering is observed immediately to the left of the minima. This is consistent with a small fraction of vesicles being deformed despite the presence of AMPs. We attribute this to inhomogeneous mixing which may give locally different salt concentration as a result of the manual procedure. In any case, this appears to a minor effect and only apparent at very high salt concentrations.