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The Ion–Specific Screening and Hofmeister Series for the Osmotic Second Virial Coefficient in Protein Solutions

By: Yuri Kalyuzhny
From: Institute for Condensed Matter Physics, Lviv
At: Instituto de Investigação Interdisciplinar, Anfiteatro
[2014-02-05] 11:00

To improve computational modeling in biology and technology, we need to deepen our understanding of electrolyte solutions and interaction of ions with charged macromolecules.  Based on our previous developments in modeling and theory, we propose a molecular level study of the ion-specific effects in aqueous solutions of polyelectrolytes and proteins. We propose a Hamiltonian type of theory for a mixture of macroions, counter ions, and co-ions in a water-like fluid. All the components are accounted for explicitly. The macroions can have simultaneously positive and negative charges, mimicking the situation occurring in protein solutions.

To solve numerically this complex model we utilize the associative mean spherical approximation (AMSA), developed earlier for the low-molecular-weight charge symmetric electrolyte solutions. Among measurable properties we choose to calculate osmotic pressure and osmotic second virial coefficient, the quantity which indicates the stability of the system: the second virial coefficient is directly correlated with the solubility of the protein represented by the Hofmeister series. Our results for the second virial coefficient will be presented for different pH values of the solution, concentration and nature of the salt and discussed in view of the experimental results for lysozyme-electrolyte mixtures.