Differentiating antimicrobial peptides interacting with lipid bilayer: Molecular signatures derived from quartz crystal microbalance with dissipation monitoring.

Many antimicrobial peptides (AMPs) kill bacteria by disrupting the lipid bilayer structure of their inner membrane. However, there is only limited quantitative information in the literature to differentiate between AMPs of differing molecular properties, in terms of how they interact with the membrane. In this study, we have used quartz crystal microbalance with dissipation monitoring (QCM-D) to probe the interactions between a supported bilayer membrane of egg phosphatidylcholine (egg PC) and four structurally different AMPs: alamethicin, chrysophsin-3, indolicidin, and sheep myeloid antimicrobial peptide (SMAP-29). Multiple signatures from the QCM-D measurements were extracted, differentiating the AMPs, that provide information on peptide addition to and lipid removal from the membrane, the dynamics of peptide-membrane interactions and the rates at which the peptide actions are initiated. The mechanistic variations in peptide action were related to the fundamental structural properties of the peptides including the hydrophobicity, hydrophobic moment, and the probability of α-helical secondary structures.