Berlin 2012 – scientific programme
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BP: Fachverband Biologische Physik
BP 14: Membranes and Vesicles
BP 14.6: Talk
Wednesday, March 28, 2012, 11:00–11:15, H 1028
Active membranes - photoswitching of azobenzene cholesterol in host lipid layers — Lars Jørgensen1, Dordaneh Zargarani2, Annika Elsen3, Klaas Loger3, Benjamin Runge3, Christian Koops3, Rainer Herges2, Bridget Murphy3, Olaf Magnussen3, and •Beate Klösgen1 — 1University of Southern Denmark, Inst. f. Phys. Chem. and Pharm. - MEMPHYS, Odense, Denmark — 2CAU Kiel, Otto Diels Inst.f. Org. Chem., Kiel, Germany — 3CAU Kiel, Inst. for Exp. and Appl. Phys., Kiel, Germany
Phosphocholine (PC) lipid membranes exhibit a sequence of thermotropic lamellar states from solid to gel to liquid ordered (LO) to liquid disordered (LD). The LD membrane conformation is considered to be the biologically relevant phase. The inoculation of guest molecules into a host lipid layer may locally modify the initial state of the host; e.g., the incorporation of cholesterol passively induces the LO phase into a region that else how is in the LD state. The presence of a protein however may result in an active system fluctuating between the LO and the LD state, depending on the conformational changes of the protein as it conducts its functional work. We here present first results obtained from studies on an active membrane model system that consists of the photoswitchable variety of cholesterol, modified by an azobenzence group (azo-Ch), and a pure POPC host layer. Upon illumination, the azo-Ch can be reversibly switched (365nm * cis / 440 nm * trans). The functionalized cholesterol serves as a mesogen the conformation of which is coupled into the host system that in turn responds by acquiring an adjustment of its (local) structure upon switching.