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Unité de Formation et de Recherche de Chimie

" Modeling aggregation and solvation of proteins in aqueous salt solutions " on 24 th of November 2017

Vendredi 24 novembre à 14h, Vojko Vlachy (Université de Ljubljana, Slovénie)

" Modeling aggregation and solvation of proteins in aqueous salt solutions "

Institut des Matériaux de Paris Centre (43.44.317). 

Abstract :

Protein aggregation is broadly important in diseases and in formulations of biological drugs. Recently we developed theoretical models for reversible protein aggregation in salt solutions. In the first case presented in this paper we treat proteins as hard spheres (or hard dumb-bells) to mimic globular proteins (1–3), such as, lysozyme and crystallins. In another example we construct an assembly of hard spheres forming Y–shaped objects to resemble monoclonal antibodies (4). In both cases the model particles are assumed decorated by the square–well binding sites. The necessary condition required for such modeling to be realistic is that proteins in solution during the experiment remain in their compact form. We used Wertheim’s TPT and/or associative MSA theories, which are well suited for systems of molecules with directional forces. We propose how to connect the solution viscosity with the antibody aggregation. We show that model bi–specific antibodies could be designed to have low viscosities, whereas regular mono–specific (two identical arms) molecules have intermediate viscosities, and 3–armed antibody molecules (all the interacting arms are attractive), have high viscosities. In the last example (5) we consider a mixture of ions, water, and model proteins. We use the same theoretical approach (associative MSA) as above to calculate the thermodynamic properties. A semi–quantitative agreement between measured and calculated values for the second virial coefficient, as functions of pH of solution, as also the added salt type and concentration, is obtained.



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