In Dip6-containing peptides (set 1), this backbone conformation is either nearly absent (e.g., p1, 5a, and 7a) or constitutes only a minor population for highly flexible peptides, such as 8a (Table , Supporting Information). In contrast, fold1-4 is well populated, or even the dominant conformation), in all Trp6-containing peptides (p3 and 15c) from set 2. The states with fold2-6 are prevalent in set 1 peptides (p1, 5a, 7a, and 8a) but are less populated in set 2 peptides (p3, 8c, 13c, 15c, and 16c). This variation in conformational populations reflects changes in the side chain packing arising from both Dip6/Trp6 and L/D substitutions in the parent peptides. In peptides with a higher population of fold2-6 MD states, we found denser molecular packing characterized by a higher number of backbone H-bonds and more stable π-cationic and stacking interactions between the side chains of adjacent Arg and Dip residues (Arg1-Dip7, Arg4-Dip5, Table , Supporting Information).