Berlin 2012 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 7: Posters: Proteins

BP 7.28: Poster

Montag, 26. März 2012, 17:30–19:30, Poster A

Aggregation of Human Antimicrobial Peptide Fragments at Interfaces — •Claudia Dannehl¹, Thomas Gutsmann², and Gerald Brezesinski¹ — ¹Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424 Potsdam — ²Research Center Borstel, Center for Medicine and Biosience, 23845 Borstel

Antimicrobial peptides (AMPs) are short, amphiphilic proteins and part of the host immune defense. They protect organisms against bacteria, viruses and fungi simply by disrupting their membrane. In our work, we focus on two fragments of the human cathelicidin and lipid monolayers as model membranes to get insight into this peptide-lipid interaction. It was shown by XR and IRRAS, that both peptides adopt an alpha-helical conformation, when adsorbed to lipid monolayers, but differ in their way of action. Both peptides lead to a fluidization of a negatively charged DPPG monolayer, indicated by an increased transition pressure from a liquid-like to a liquid-condensed phase (seen by GIXD and IRRAS), but the increase in surface pressure and the change in the amide band upon adsorption is peptide specific. We assume that the stronger peptide-lipid interaction of one peptide is accompanied by a peptide aggregation at the interface, as studied by IRRAS on monolayers and CD spectroscopy with SDS in bulk (above the CMC). No changes in the spectra were recorded with IRRAS for zwitterionic lipids (DPPC, DOPC) and CD for the cationic CTAB , which means that the aggregation of the peptide is dominated by the charge density of the target.