Phase coexistence in a DLVO model of globular protein solutions

Globular protein solutions of lysozyme in water and added salt are modelled according to the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, in order to determine their fluid-fluid and fluid-solid coexistence lines. Calculations are based on both computer simulations and theoretical approaches. Our results indicate that, when the potential parameters are obtained by fitting physical properties directly deducible from either static or dynamic light scattering data, the fluid-fluid phase coexistence predictions agree quite well with the experiments. Our description of the solid phase allows only a qualitative reproduction of the experimental solubility boundaries. The overall accuracy of our predictions is discussed in view of the well known limitations of the DLVO representation of protein solutions.