Dresden 2017 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 1: Computational Biophysics (Joint Session BP/DY)
BP 1.5: Vortrag
Montag, 20. März 2017, 10:45–11:00, ZEU 250
Interaction of hyperbranched polyglycerol sulfate with proteins: calorimetry versus computer simulations — •Xiao Xu1,2, Qidi Ran3, Rainer Haag3, Matthias Ballauff1,2, and Joachim Dzubiella1,2 — 1Institut für Weiche Materie und funktionale Materialien, Helmholtz-Zentrum Berlin — 2Institut für Physik, Humboldt-Universität zu Berlin — 3Institut für Chemie und Biochemie, Freie Universität Berlin
Using Isothermal Titration Calorimetry (ITC) and coarse-grained (implicit solvent/explicit salt) Langevin computer simulations, we study the interaction of hyperbranched polyglycerol sulfate (hPGS) with two oppositely charged serum proteins, i.e. human serum albumin (HSA) (-) and lysozyme (+). The simulation reveals explicitly the structural properties of the complexation. We demonstrate that the driving force of the complexation in both cases originates mainly from the release of condensed counter-ions from the polymer upon binding. The binding constant fitted by single set of identical sites model shows very weak dependence on polymer size for both proteins. By applying an excluded-volume (EV) model to fit the ITC data the explict profile of binding free energy for multi-site binding between lysozyme and hPGS can be obtained. The experimental data coincides with computer simulation quantitatively especially for high generation of hPGS, which makes the simulation a useful tool to predict hPGS binding to targeted proteins such as selectins.