Regensburg 2013 – scientific programme
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DY: Fachverband Dynamik und Statistische Physik
DY 36: Statistical Physics in Biological Systems IV (joint with BP)
DY 36.12: Talk
Friday, March 15, 2013, 12:30–12:45, H44
Sequence depending membrane-activity of amphiphilic polymers — •Marco Werner1,2 and Jens-Uwe Sommer1,2 — 1Leibniz-Institut für Polymerforschung Dresden, Germany — 2Technische Universität Dresden, Germany
Using the bond fluctuation model with explicit solvent we investigate self-assembled bilayer membranes interacting with random copolymers of hydrophilic/-phobic monomers under variation of the fraction of hydrophobic monomers, H. Our simulation data indicates that polymers localize at the membrane-solvent interface for values of H≳1/2, where the polymer forms excess blobs in the solvent- and lipid tail phases to increase the number of preferred contacts to both environments. Excess blobs with hydrophobic majority are inhibited to freely expand in the lipid tail phase due to the self-organized packing of lipids. Therefore, the number of preferred polymer-environment contacts is balanced on both sides for values of H slightly larger than H=1/2. Here, the polymer shows the largest membrane-activity as indicated by a maximum of polymer-induced permeability for solvent. Testing a larger population of random polymer sequences we demonstrate that heterogeneity of the amphiphilic components of the polymer on a scale smaller than the lipid tail length is a key feature for polymer-induced bilayer perturbations. This seems to be confirmed by testing polymers with alternating sequences with hydrophobic blocks of size smaller than the lipid tail length, for which the polymer-induced membrane permeability for solvent is larger than on average for the population of random copolymers.