Please use this identifier to cite or link to this item: http://scholarbank.nus.edu.sg/handle/10635/16290
Title: Phase separations in protein solutions: A Monte Carlo simulation study
Authors: LI JIANGUO
Keywords: protein crystallization, phase separation, IgG, polymer, solvent effect, second virial coefficient
Issue Date: 19-Jun-2009
Source: LI JIANGUO (2009-06-19). Phase separations in protein solutions: A Monte Carlo simulation study. ScholarBank@NUS Repository.
Abstract: This work explores phase separation, including crystallization, of the non-globular, therapeutic protein Immunoglobulin G (IgG) as a function of solutions variables (such as ionic strength, pH, and added polymer) using a simple four-site geometric model to capture the shape of the protein. We use the four-site model with more complicated interaction potentials to study the effect of solution variables on the phase separation of IgG solutions. We observe a non-monotonic change of the critical polymer density with the polymer size, and use a rescaling of the polymer density to obtain a monotonic variation of the critical point as observed in the case of simple fluids. Based on this, we have developed a simple equation for estimating the minimum amount of polymer needed to induce the liquid-liquid phase separation that will be a useful guidance for the experimentalist. We also propose a temperature-dependent potential to account for the role of solvent. This temperature-dependent potential yields a closed-loop phase diagram with both a lower critical solution temperature (LCST) and an upper critical solution temperature (UCST), in good agreement with the experiments. The results also indicate that it is possible to capture the fundamental features of complex system using simple models.
URI: http://scholarbank.nus.edu.sg/handle/10635/16290
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