Berlin 2015 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 56: Membranes and vesicles II (joint session BP, CPP)

CPP 56.2: Talk

Wednesday, March 18, 2015, 15:30–15:45, H 1028

Lipid composition in fusion of model membrane systems studied by x-ray diffraction — •Sebastian Köhler¹, Yihui Xu¹, Ziad Khattari², and Tim Salditt¹ — ¹Institut für Röntgenphysik, Georg-August-Universität Göttingen — ²Department of Physics, Hashemite University, Zarqa, Jordan

We have investigated the structure and interaction of solid-supported multilamellar phopholipid bilayers as model systems for membrane fusion in view of the formation of stalks (putative intermediate structures occurring during the fusion process). X-ray reflectivity and grazing incidence small angle x-ray scattering measurements have been performed on bilayer stacks of different ternary and quaternary lipid mixtures at varying osmotic pressure. Analysis of the obtained electron density profiles and pressure-distance curves reveals systematic changes in structure and hydration repulsion. The osmotic pressure needed to induce stalk formation at the transition from the fluid lamellar to the rhombohedral phase indicates how membrane fusion properties are modified by bilayer composition. We present phase diagrams for all studied lipid mixtures.