Prediction of thermodynamic instabilities of protein solutions from simple protein-protein interactions

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• 作者：Tommaso D鈥橝gostino ; Jos茅 Ram贸n Solana ; Antonio Emanuele
• 关键词：Liquid&ndash ; liquid demixing ; Square well potential ; Protein solution ; Spinodal line ; Solvent mediated protein&ndash ; protein interaction ; Entropy driven phase transition
• 刊名：Chemical Physics
• 出版年：16 October, 2013
• 年：2013
• 卷：424
• 期：Complete
• 页码：50-55
• 全文大小：553 K

文摘

Statistical thermodynamics of protein solutions is often studied in terms of simple, microscopic models of particles interacting via pairwise potentials. Such modelling can reproduce the short range structure of protein solutions at equilibrium and predict thermodynamics instabilities of these systems. We introduce a square well model of effective protein-protein interaction that embeds the solvent鈥檚 action. We modify an existing model by considering a well depth having an explicit dependence on temperature, i.e. an explicit free energy character, thus encompassing the statistically relevant configurations of solvent molecules around proteins. We choose protein solutions exhibiting demixing upon temperature decrease (lysozyme, enthalpy driven) and upon temperature increase (haemoglobin, entropy driven). We obtain satisfactory fits of spinodal curves for both the two proteins without adding any mean field term, thus extending the validity of the original model. Our results underline the solvent role in modulating or stretching the interaction potential.