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Zwitterions fine-tune interactions in electrolyte solutions

Cellular organisms regulate electrolyte composition in the cytosol to optimize intracellular molecular interactions at the same time as balancing external osmotic pressure. While osmotic pressure can be tuned using multiple ionic, zwitterionic, and nonionic solutes, interactions between proteins and...

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Autores principales: Hallett, James E., Agg, Kieran J., Perkin, Susan
Formato: Online Artículo Texto
Lenguaje:English
Publicado: National Academy of Sciences 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9974414/
https://www.ncbi.nlm.nih.gov/pubmed/36787353
http://dx.doi.org/10.1073/pnas.2215585120
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author Hallett, James E.
Agg, Kieran J.
Perkin, Susan
author_facet Hallett, James E.
Agg, Kieran J.
Perkin, Susan
author_sort Hallett, James E.
collection PubMed
description Cellular organisms regulate electrolyte composition in the cytosol to optimize intracellular molecular interactions at the same time as balancing external osmotic pressure. While osmotic pressure can be tuned using multiple ionic, zwitterionic, and nonionic solutes, interactions between proteins and other macromolecules are sensitive to the precise composition of the medium. Nonetheless, the roles of individual ions and nonionic solutes in mediating cellular interactions remain relatively unexplored, and standard buffer solutions used in laboratory studies often contain only a few simple salts. Here, we report on model experiments investigating the combined effect of ionic and zwitterionic solutes on interaction forces across electrolytes, revealing a clear role for zwitterions in modifying interactions compared to simple salt solutions. First, we find that zwitterions act to disrupt water layering at interfaces, leading to smoothed interaction potentials. Second, we find that zwitterions strengthen electrostatic repulsions by enhancing effective surface charge. Third, zwitterions enhance the effective dielectric permittivity of the solution, and this “dielectricizer” effect extends the range of electrostatic repulsions compared to solutions without zwitterion present. The latter two effects are likely important in stabilizing proteins and other macromolecules when external osmotic and mechanical pressure are very high and simple ionic solutes alone would lead to collapse.
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spelling pubmed-99744142023-03-02 Zwitterions fine-tune interactions in electrolyte solutions Hallett, James E. Agg, Kieran J. Perkin, Susan Proc Natl Acad Sci U S A Physical Sciences Cellular organisms regulate electrolyte composition in the cytosol to optimize intracellular molecular interactions at the same time as balancing external osmotic pressure. While osmotic pressure can be tuned using multiple ionic, zwitterionic, and nonionic solutes, interactions between proteins and other macromolecules are sensitive to the precise composition of the medium. Nonetheless, the roles of individual ions and nonionic solutes in mediating cellular interactions remain relatively unexplored, and standard buffer solutions used in laboratory studies often contain only a few simple salts. Here, we report on model experiments investigating the combined effect of ionic and zwitterionic solutes on interaction forces across electrolytes, revealing a clear role for zwitterions in modifying interactions compared to simple salt solutions. First, we find that zwitterions act to disrupt water layering at interfaces, leading to smoothed interaction potentials. Second, we find that zwitterions strengthen electrostatic repulsions by enhancing effective surface charge. Third, zwitterions enhance the effective dielectric permittivity of the solution, and this “dielectricizer” effect extends the range of electrostatic repulsions compared to solutions without zwitterion present. The latter two effects are likely important in stabilizing proteins and other macromolecules when external osmotic and mechanical pressure are very high and simple ionic solutes alone would lead to collapse. National Academy of Sciences 2023-02-14 2023-02-21 /pmc/articles/PMC9974414/ /pubmed/36787353 http://dx.doi.org/10.1073/pnas.2215585120 Text en Copyright © 2023 the Author(s). Published by PNAS. https://creativecommons.org/licenses/by/4.0/This open access article is distributed under Creative Commons Attribution License 4.0 (CC BY) (https://creativecommons.org/licenses/by/4.0/) .
spellingShingle Physical Sciences
Hallett, James E.
Agg, Kieran J.
Perkin, Susan
Zwitterions fine-tune interactions in electrolyte solutions
title Zwitterions fine-tune interactions in electrolyte solutions
title_full Zwitterions fine-tune interactions in electrolyte solutions
title_fullStr Zwitterions fine-tune interactions in electrolyte solutions
title_full_unstemmed Zwitterions fine-tune interactions in electrolyte solutions
title_short Zwitterions fine-tune interactions in electrolyte solutions
title_sort zwitterions fine-tune interactions in electrolyte solutions
topic Physical Sciences
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9974414/
https://www.ncbi.nlm.nih.gov/pubmed/36787353
http://dx.doi.org/10.1073/pnas.2215585120
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