Regensburg 2016 – scientific programme

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BP: Fachverband Biologische Physik

BP 57: Membranes and Vesicles I

BP 57.2: Talk

Thursday, March 10, 2016, 10:00–10:15, H43

Incorporation of Aescin in DMPC vesicles — •Ramsia Sreij, Carina Dargel, and Thomas Hellweg — Physical and Biophysical Chemistry, Universitätsstraße 25, 33615 Bielefeld

The function of membrane proteins depends on the lipid bilayer thickness (d_z) and its properties. d_z is studied in model membrane systems in form of unilamellar vesicles (ULVs) consisting of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC). DMPC vesicles undergo a phase transition from gel to fluid phase at a temperature T_M = 23.6 ^∘C. Saponins are a diverse class of natural, plant derived amphiphilic molecules with a peculiar molecular structure made of a hydrophobic scaffold and hydrophilic oligosaccharide chains. They have strong surface activity and are used as natural emulsifiers and foaming agents in food, pharmaceutical and other industries. Their incorporation into the membrane of living cells reduces the cholesterol bioaccessibility by displacement of cholesterol molecules from the bile salt micelles. We studied the saponin Aescin to demonstrate the effect of its incorporation on the lipid bilayer thickness and T_M of small unilamellar DMPC vesicles produced by extrusion. We use small and wide angle X-ray scattering (SWAXS) to measure the effects on d_z in dependence of a varying amount of incorporated Aescin. By differential scanning calorimetry (DSC) and dynamic light scattering (DLS) experiments we show the influence of the saponin incorporation on T_M.
B.A. Brüning, S. Prevost, R. Stehle, R. Steitz, P. Falus, B. Farago, and T. Hellweg, Biochim. Biophys. Acta, 1838, 2412-2419.