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Title: Charged patchy particle models in explicit salt: Ion distributions, electrostatic potentials, and effective interactions

We introduce a set of charged patchy particle models (CPPMs) in order to systematically study the influence of electrostatic charge patchiness and multipolarity on macromolecular interactions by means of implicit-solvent, explicit-ion Langevin dynamics simulations employing the Gromacs software. We consider well-defined zero-, one-, and two-patched spherical globules each of the same net charge and (nanometer) size which are composed of discrete atoms. The studied mono- and multipole moments of the CPPMs are comparable to those of globular proteins with similar size. We first characterize ion distributions and electrostatic potentials around a single CPPM. Although angle-resolved radial distribution functions reveal the expected local accumulation and depletion of counter- and co-ions around the patches, respectively, the orientation-averaged electrostatic potential shows only a small variation among the various CPPMs due to space charge cancellations. Furthermore, we study the orientation-averaged potential of mean force (PMF), the number of accumulated ions on the patches, as well as the CPPM orientations along the center-to-center distance of a pair of CPPMs. We compare the PMFs to the classical Derjaguin-Verwey-Landau-Overbeek theory and previously introduced orientation-averaged Debye-Hückel pair potentials including dipolar interactions. Our simulations confirm the adequacy of the theories in their respective regimes of validity, while low saltmore » concentrations and large multipolar interactions remain a challenge for tractable theoretical descriptions.« less
Authors:
;  [1] ;  [2] ;  [2] ;  [3]
  1. Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin, 14109 Berlin (Germany)
  2. (Germany)
  3. Department of Physical Chemistry, University of Chemistry and Technology, Prague, 166 28 Praha 6 (Czech Republic)
Publication Date:
OSTI Identifier:
22493522
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 143; Journal Issue: 6; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ABUNDANCE; ATOMS; BUILDUP; COBALT IONS; COMPARATIVE EVALUATIONS; COMPUTERIZED SIMULATION; CONCENTRATION RATIO; G CODES; MULTIPOLARITY; ORIENTATION; POTENTIALS; PROTEINS; SALTS; SOLVENTS; SPACE CHARGE; SPATIAL DISTRIBUTION; SPHERICAL CONFIGURATION