The proposed research is concerned with separating a mixture of proteins in aqueous solution through selective precipitation, i. e., by formation of a phase rich in the target protein in equilibrium with a second phase where the concentration of the target protein is very low. Precipitation is achieved by salts or nonionic polymers or both. To obtain a quantitative understanding of protein- precipitation equilibria, a molecular-thermodynamic model based on an extended Guggenheim/McMillan-Mayer osmotic viral expansion is presented. The goal of this research is to establish an engineering-oriented correlation for rational design of protein-precipitation processes. A long-range benefit of this research is that it is likely to provide useful knowledge for better understanding of protein crystallization.
