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AKB: Biologische Physik

AKB 50: Poster Session "Biological Physics"

AKB 50.67: Poster

Freitag, 12. März 2004, 10:30–13:00, B

X-ray and neutron reflectivity analysis of peptide-lipid model systems — •Chenghao Li und Tim Salditt — Institut fuer Roentgenphysik, Universitaet Goettingen

Using x-ray and neutron reflectivity, we have investigated the structure of solid-supported, multilamellar lipid membranes with and without membrane active, antimicrobial peptides. To analyse the measured reflectivity curve we fit the curves to a model bilayer profile of adjustable resolution and deduce detailed structural parameters of the bilayers on an absolute scale of the scattering length density. The model is implemented in the framework of a semi-kinematical scattering theory. We have analysed reflectivity curves for lipids POPC (1-Palmitoyl-2-Oleoyl-sn-Glycero-3-Phosphocholine), DMPC (1,2-Dimyristoyl-sn-Glycero-3-Phosphatidylcholin, mixture of POPC/POPS (1-Palmitoyl-2-Oleoyl-sn-Glycero-3-[Phospho-L-Serine]) ) in 3:1 mol ratio, and mixture of DMPC/DMPG (1,2-Dimyristoyl-sn-Glycero-3-[Phospho-rac-(1-glycerol)]) also in 3:1 mol ratio with and without the antibiotic peptide magainin 2. For the pure OPPC lipid, the resulting bilayer electron density profile agrees well with previously published data of a molecular dynamics (MD) simulation.