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Weiche Materie Poster: Do., 13:00–15:30 D-P335
Influence of melittin on phase behaviour of lipids with various headgroups
Maria Hanulova 1 , Sergio S. Funari 1
1 Hasylab at Desy, Notkestrasse 85, Hamburg, Germany
Melittin, a 26 amino acid peptide, is the toxin of bee venom with hemolytic and antibacterial
activity. It binds to natural and model lipid membranes and at high molar
ratios disrupts them. Using X-ray diffraction, we studied the influence of melittin on
the phase behaviour of model lipid membranes composed of phospholipids with various
headgroups: phosphatidylcholine, prevalent in membranes of red blood cells, phosphatidylethanolamine,
main component of bacterial membranes, and phosphatidylglycerol,
also important in bacterial membranes. We also studied lipid mixtures mimicking
the composition of cell membranes. At lipid:protein ratios used in this study, 50 to
10000, the membrane is preserved, but melittin induces phase changes. In palmitoyloleoyl
phosphatidylethanolamine, melittin induces two coexisting cubic phases and in
palmitoyl-oleoyl phosphatidylcholine a phase separation in the lamellar phase.