Like-charged protein-polyelectrolyte complexation driven by charge patches.
We study the pair complexation of a single, highly charged polyelectrolyte (PE) chain (of 25 or 50 monomers) with like-charged patchy protein models (CPPMs) by means of implicit-solvent, explicit-salt Langevin dynamics computer simulations. Our previously introduced set of CPPMs embraces well-defined zero-, one-, and two-patched spherical globules each of the same net charge and (nanometer) size with mono- and multipole moments comparable to those of globular proteins with similar size. We observe large binding affinities between the CPPM and the like-charged PE in the tens of the thermal energy, kBT, that are favored by decreasing salt concentration and increasing charge of the patch(es). Our systematic analysis shows a clear correlation between the distance-resolved potentials of mean force, the number of ions released from the PE, and CPPM orientation effects. In particular, we find a novel two-site binding behavior for PEs in the case of two-patched CPPMs, where intermediate metastable complex structures are formed. In order to describe the salt-dependence of the binding affinity for mainly dipolar (one-patched) CPPMs, we introduce a combined counterion-release/Debye-Hückel model that quantitatively captures the essential physics of electrostatic complexation in our systems.
Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin, 14109 Berlin, Germany.
Cemil
C
Yigit
Department of Physical Chemistry, University of Chemistry and Technology, Prague, 166 28 Praha 6, Czech Republic.
Jan
J
Heyda
Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin, 14109 Berlin, Germany.
Matthias
M
Ballauff
Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin, 14109 Berlin, Germany.
Joachim
J
Dzubiella
D003198:Computer Simulation; D004573:Electrolytes / Q000737:chemistry*; D008956:Models, Chemical; D011506:Proteins / Q000737:chemistry*; D012492:Salts / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D055672:Static Electricity; D013499:Surface Properties
D004573:Electrolytes; D011506:Proteins; D012492:Salts; D012997:Solvents