Why pH Titration in Protein Solutions Follows a Hofmeister Series
Date
2006
Authors
Bostrom, Mathias Anders
Lonetti, Barbara
Fratini, Emiliano
Baglioni, Piero
Ninham, Barry
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American Chemical Society
Abstract
Measurements of pH in single-phase cytochrome c suspensions are reported. The pH, as determined by a glass electrode, has a fixed value. With the addition of salt, the supposedly fixed pH changes strongly. The pH depends on salt type and concentration and follows a Hofmeister series. A theoretical interpretation is given that provides insights into such Hofmeister effects. These occur generally in protein solutions. While classical electrostatic models provide partial understanding of such trends in protein solutions, they fail to explain the observed ion specificity. Such models neglect electrodynamic fluctuation (dispersion) forces acting between ions and proteins. We use a Poisson-Boltzmann cell model that takes these ionic dispersion potentials between ions and proteins into account. The observed ion specificity can then be accounted for. Proteins act as buffers that display similar salt-dependent pH trends not previously explained.
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Keywords
Keywords: Concentration (process); Electrochemical electrodes; Electrodynamics; pH; Titration; Electrodynamic fluctuation; Glass electrodes; Hofmeister series; Proteins; cytochrome c; protein; algorithm; animal; article; chemical model; chemistry; horse; pH; soluti
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Source
Journal of Physical Chemistry B
Type
Journal article
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2037-12-31
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