Owing to the nature of bilayer elasticity, the effects of lateral packing cannot be discussed without addressing the vertical structure and density profile, which are closely interrelated. Namely, the effects of hydrophobic matching and interfacial anchoring (Killian and Nyholm 2006) interfere with the lateral forces. Hydrophobic matching and interfacial anchoring are especially important for the presented peptide species, as all of them hold two flanking tryptophan residues. The magnitude of hydrophobic mismatch is considered to be a function of the distance between interfacial anchoring residues, here tryptophans, and not the overall peptide length (De Planque and Killian 2003) . In this respect, tryptophan residues are known to provide the highest tendency for localization at the interface between the lipid bilayer core and the polar lipid headgroup. Hydrogen bonding and electrostatic interactions are discussed to account for the interfacial anchoring and z positioning of membrane-incorporated peptides (De Planque and Killian 2003; Doux and Killian 2010) .