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BP: Fachverband Biologische Physik

BP 12: Poster II

BP 12.35: Poster

Dienstag, 2. April 2019, 14:00–16:00, Poster B2

DMPC/cholesterol membranes at high hydrostatic pressure — •Göran Surmeier, Michael Paulus, Christian Sternemann, Susanne Dogan, Mike Moron, Marc Moron, and Julia Nase — Fakultät Physik/DELTA, TU Dortmund, 44221 Dortmund, Germany

Phospholipid bilayers, which are the basic component of cell membranes, form various liquid-crystalline and gel-like phases depending on temperature, pressure, and their composition. A typical constituent that regulates the structure of cell membranes is cholesterol. Due to its rigid sterol rings, it affects the mobility and order of lipid tail groups. We conducted a small angle X-ray scattering (SAXS) and X-ray reflectivity (XRR) study on the structure of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) model membranes containing cholesterol at high hydrostatic pressures. We were able to extract a detailed pressure- and cholesterol content-dependent phase diagram of multi-lamellar DMPC vesicles in the gel-like regime at 20 °C from SAXS. Additionally, XRR was used to obtain more in-depth information about the vertical membrane structure of solid-supported DMPC/cholesterol multilayers in an aqueous buffer solution. Combining both techniques enables to distinguish substrate-, pressure- and composition-induced effects. We observed that cholesterol strongly affects the compressibility of the membranes. At high concentrations, the spacing changes linearly over the whole pressure range, indicating that configurational changes are suppressed. Experiments were performed at beamlines BL9 at DELTA (Dortmund, Germany) and ID31 at the ESRF (Grenoble, France).