Structural modifications induced by the binding of saturated and unsaturated phospholipids to a small antimicrobial peptide KDDDD-OH (KD4) were examined by infrared, electron microscopy, and Raman techniques, and turbidity measurements. The model membranes considered were the saturated Dipalmitoyl Phosphatidylcholine (DPPC) and unsaturated Palmitoyloleoyl phosphatidylcholine (POPC). Infrared and Raman spectra revealed that KD4 mainly adopts a mixture of a-helix (31%), �-sheet (24%) and turn (45%) structures.  In the presence of POPC, KD4 adopts mainly a �-sheet structure, while remaining the same in the presence of DPPC. The a-form is also present, its amount being higher in POPC than in DPPC. KD4 was found to interact strongly with monolayers containing POPC, leading to a rigidification of the lipid acyl chains. KD4 showed a tendency to aggregate in aqueous solution in the presence of POPC, as revealed by turbidity measurements. The aggregation was associated with conformational changes.  Electron micrographs show fibril-like particles

Interaction of saturated and unsaturated phospholipid vesicles with a small antibacterial peptide

243rd National Meeting (2012)

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