The study shows that the antimicrobial peptide LL‑37 can slip into bacterial‑like membranes and make the lipids move faster, which helps explain how it kills bacteria. However, the experiments were done on simple lab‑made vesicles, not human cells, so the findings don’t directly tell you how to use LL‑37 for health or performance.

The mechanism of action of antimicrobial peptides (AMPs) has been debated over many years, and various models have been proposed. In this work we combine small angle X-ray/neutron scattering (SAXS/SANS) techniques to systematically study the effect of AMPs on the cytoplasmic membrane of <i>Escherichia coli</i> bacteria using a simplified model system of 4&#x2009;:&#x2009;1 DMPE&#x2009;:&#x2009;DMPG ([1,2-dimyristoyl-<i>sn-glycero</i>-3-phosphoethanolamine]&#x2009;:&#x2009;[1,2-dimyristoyl-<i>sn-glycero</i>-3-phospho-(10-<i>rac</i>-glycerol)]) phospholipid unilamellar vesicles. The studied antimicrobial peptides aurein 1.2, indolicidin, LL-37, lacticin Q and colistin vary in size, charge, degree of helicity and origin. The peptides insert into the bilayer to various degrees, and are found to accelerate the dynamics of phospholipids significantly as seen by time resolved SANS (TR-SANS) measurements, with the exception of colistin that is suggested to rather interact with lipopolysaccharides (LPS) on the outer membrane of <i>E. coli</i>. We compare these results with earlier published data on model systems based on PC-lipids (phosphatidylcholines), showing comparable effect with regards to peptide insertion and effect on dynamics. However, model systems based on PE-lipids (phosphatidylethanolamine) are more prone to destabilisation upon addition of peptides, with formation of multilamellar structures and morphological changes. These properties of PE-vesicles lead to less conclusive results regarding peptide effect on structure and dynamics of the membrane.