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Multisite Ion Model in Concentrated Solutions of Divalent Cations (MgCl(2) and CaCl(2)): Osmotic Pressure Calculations
[Image: see text] Accurate force field parameters for ions are essential for meaningful simulation studies of proteins and nucleic acids. Currently accepted models of ions, especially for divalent ions, do not necessarily reproduce the right physiological behavior of Ca(2+) and Mg(2+) ions. Saxena a...
Autores principales: | , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
American Chemical
Society
2014
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4291043/ https://www.ncbi.nlm.nih.gov/pubmed/25482831 http://dx.doi.org/10.1021/jp507008x |
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author | Saxena, Akansha García, Angel E. |
author_facet | Saxena, Akansha García, Angel E. |
author_sort | Saxena, Akansha |
collection | PubMed |
description | [Image: see text] Accurate force field parameters for ions are essential for meaningful simulation studies of proteins and nucleic acids. Currently accepted models of ions, especially for divalent ions, do not necessarily reproduce the right physiological behavior of Ca(2+) and Mg(2+) ions. Saxena and Sept (J. Chem. Theor. Comput.2013, 9, 3538–3542) described a model, called the multisite-ion model, where instead of treating the ions as an isolated sphere, the charge was split into multiple sites with partial charge. This model provided accurate inner shell coordination of the ion with biomolecules and predicted better free energies for proteins and nucleic acids. Here, we expand and refine the multisite model to describe the behavior of divalent ions in concentrated MgCl(2) and CaCl(2) electrolyte solutions, eliminating the unusual ion–ion pairing and clustering of ions which occurred in the original model. We calibrate and improve the parameters of the multisite model by matching the osmotic pressure of concentrated solutions of MgCl(2) to the experimental values and then use these parameters to test the behavior of CaCl(2) solutions. We find that the concentrated solutions of both divalent ions exhibit the experimentally observed behavior with correct osmotic pressure, the presence of solvent separated ion pairs instead of direct ion pairs, and no aggregation of ions. The improved multisite model for (Mg(2+) and Ca(2+)) can be used in classical simulations of biomolecules at physiologically relevant salt concentrations. |
format | Online Article Text |
id | pubmed-4291043 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2014 |
publisher | American Chemical
Society |
record_format | MEDLINE/PubMed |
spelling | pubmed-42910432015-12-08 Multisite Ion Model in Concentrated Solutions of Divalent Cations (MgCl(2) and CaCl(2)): Osmotic Pressure Calculations Saxena, Akansha García, Angel E. J Phys Chem B [Image: see text] Accurate force field parameters for ions are essential for meaningful simulation studies of proteins and nucleic acids. Currently accepted models of ions, especially for divalent ions, do not necessarily reproduce the right physiological behavior of Ca(2+) and Mg(2+) ions. Saxena and Sept (J. Chem. Theor. Comput.2013, 9, 3538–3542) described a model, called the multisite-ion model, where instead of treating the ions as an isolated sphere, the charge was split into multiple sites with partial charge. This model provided accurate inner shell coordination of the ion with biomolecules and predicted better free energies for proteins and nucleic acids. Here, we expand and refine the multisite model to describe the behavior of divalent ions in concentrated MgCl(2) and CaCl(2) electrolyte solutions, eliminating the unusual ion–ion pairing and clustering of ions which occurred in the original model. We calibrate and improve the parameters of the multisite model by matching the osmotic pressure of concentrated solutions of MgCl(2) to the experimental values and then use these parameters to test the behavior of CaCl(2) solutions. We find that the concentrated solutions of both divalent ions exhibit the experimentally observed behavior with correct osmotic pressure, the presence of solvent separated ion pairs instead of direct ion pairs, and no aggregation of ions. The improved multisite model for (Mg(2+) and Ca(2+)) can be used in classical simulations of biomolecules at physiologically relevant salt concentrations. American Chemical Society 2014-12-08 2015-01-08 /pmc/articles/PMC4291043/ /pubmed/25482831 http://dx.doi.org/10.1021/jp507008x Text en Copyright © 2014 American Chemical Society This is an open access article published under an ACS AuthorChoice License (http://pubs.acs.org/page/policy/authorchoice_termsofuse.html) , which permits copying and redistribution of the article or any adaptations for non-commercial purposes. |
spellingShingle | Saxena, Akansha García, Angel E. Multisite Ion Model in Concentrated Solutions of Divalent Cations (MgCl(2) and CaCl(2)): Osmotic Pressure Calculations |
title | Multisite
Ion Model in Concentrated Solutions of Divalent
Cations (MgCl(2) and CaCl(2)): Osmotic Pressure
Calculations |
title_full | Multisite
Ion Model in Concentrated Solutions of Divalent
Cations (MgCl(2) and CaCl(2)): Osmotic Pressure
Calculations |
title_fullStr | Multisite
Ion Model in Concentrated Solutions of Divalent
Cations (MgCl(2) and CaCl(2)): Osmotic Pressure
Calculations |
title_full_unstemmed | Multisite
Ion Model in Concentrated Solutions of Divalent
Cations (MgCl(2) and CaCl(2)): Osmotic Pressure
Calculations |
title_short | Multisite
Ion Model in Concentrated Solutions of Divalent
Cations (MgCl(2) and CaCl(2)): Osmotic Pressure
Calculations |
title_sort | multisite
ion model in concentrated solutions of divalent
cations (mgcl(2) and cacl(2)): osmotic pressure
calculations |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4291043/ https://www.ncbi.nlm.nih.gov/pubmed/25482831 http://dx.doi.org/10.1021/jp507008x |
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