Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

AKB: Biologische Physik

AKB 40: Poster Session II

AKB 40.32: Poster

Mittwoch, 29. März 2006, 16:30–19:30, P3

Electrostatic Interactions modulated within Monolayers of charged Amphiphilic Peptide — •Ann Falk, Stefan Surber, Lydia Woiterski, Josef Käs, and Carsten Selle — Universität Leipzig, Fakultät Physik & Geowissenschaften, Exphysik I, PWM

We performed a fundamental investigation on the effect of the antimicrobial peptide gramicidin S (GS) on the properties of lipid monolayers as membrane mimics. As a first step, pure GS monolayers on subphases of physiologic ionic strength were characterized at room temperature (I ~ 0.19 M). Pressure-area isotherms of GS monolayers were recorded indicating a phase transition from a liquid to a solid phase in two dimensions that was dependent on the subphase pH. This variation can be explained by pH-dependent basic amino acid side group charges of GS. Brewster-Angle-Microscopy was used to monitor the solid-phase domain growth during the 2 D phase transition. We observed that the shape of the solid domains is surprisingly sensitive to pH alterations over ten orders of magnitude. X-ray reflectivity and grazing incidence diffraction measurement were performed under analog conditions. First results of experiments on the interactions of GS with various phospholipids representing bacterial and mammalian membrane components are also presented.