Two types of backbone conformations were identified based on the C-C distance for atoms of Arg1 and Arg4, flanking the hydrophobic region. The first one contains a turn between these residues (named "fold1-4") and features a turn between the polar Arg1 and Arg4, spatially separating the polar (Arg1-Arg4) and apolar (Dip5-Dip7) regions (Figure ). The alternative backbone configuration, termed as "fold2-6", is characterized by an increased (> 8 Å) distance between C atoms of Arg1 and Arg4 and includes a different set of turns (among which the most common turn is Arg2-Dip6/Trp6, see Table , Supporting Information). The population distributions of these conformations correlate well with the hemolytic data across the entire set of the tested peptides (Table , Supporting Information). It was shown that the two sets differ markedly in the occupancy of states with fold1-4 conformation.