In in-house experiments, six intensive equidistant Bragg peaks were obtained for the labeled (7) as well as the unlabeled (2) hairpin species (Fig. 9b ) due to the higher radiation energies (Cu-K a = 8.048 keV) and improved alignment. For peptides labeled with the Fmoc-Phe(4-I)-OH building block, species 2 served as reference structure. In case of hairpin 8, labeled with Fmoc-5,5-diiodoallylglycine-OH, analog 9 with the sequence H-(FY) 5 WW-Gallylglycine-PG-(FY) 5 WW-OH was applied as unlabeled species. As the electron density profiles of the lipid bilayer structures obtained from in-house experiments were more resolved, these data were used to estimate the respective changes in hydrophobic thickness (see below).