Abstract
Cell−surface polysaccharides are essential to many aspects of physiology, serving as a highly conserved evolutionary feature of life and as an important part of the innate immune system in mammals. Here, as simplified biophysical models of these sugar coatings, we present results of molecular dynamics simulations of hyaluronic acid and heparin brushes that show important effects of ion pairing, water dielectric decrease, and coion exclusion. As in prior studies of macromolecular crowding under physiologically relevant salt concentrations, our results show equilibria with electroneutrality attained through screening and pairing of brush anionic charges by monovalent cations at the atomistic detail. Most surprising is the reversal of the Donnan potential obtained from both nonpolarizable and Drude polarizable force fields, in contrast to what would be expected based on electrostatic Boltzmann partitioning alone. Water dielectric decrement within the brush domain is also associated with Born hydration-driven cation exclusion from the brush. We observe that the primary partition energy attracting cations to attain brush electroneutrality is the ion pairing or salt-bridge energy. Potassium and sodium pairings to glycosaminoglycan carboxylates and sulfates show similar abundance of contact-pairing and solvent-separated pairing. We conclude that in these crowded macromolecular brushes, ion-pairing, Born-hydration, and electrostatic potential energies all contribute to attain electroneutrality and should therefore contribute in mean-field models to accurately represent brush electrostatics.
Recommended Citation
Sterling, J. D., Jiang, W., Botello-Smith, W. M., & Luo, Y. L. (2021). Ion Pairing And Dielectric Decrement In Glycosaminoglycan Brushes. Journal of Physical Chemistry B, 125(10), pp. 2771-2780. American Chemical Society.
The definitive version is available at https://doi.org/10.1021/acs.jpcb.0c11571
Department(s)
Business and Information Technology
Second Department
Chemical and Biochemical Engineering
International Standard Serial Number (ISSN)
1520-5207; 1520-6106
Document Type
Article - Journal
Document Version
Citation
File Type
text
Language(s)
English
Rights
© 2025 American Chemical Society, All rights reserved.
Publication Date
18 Mar 2021
PubMed ID
33662212
Included in
Biochemical and Biomolecular Engineering Commons, Health Information Technology Commons, Technology and Innovation Commons
Comments
National Science Foundation, Grant ACI-154862