Theoretical investigations of simple model protein solutions

Thermodynamically self-consistent integral equation theories and computer simulations are applied to the investigation of thermodynamic and structural properties as well as to the determination of the phase diagram of the hard-core Yukawa fluid. We consider different Yukawa-tail screening lengths lambda, going up to lambda = 9, when the potential becomes so short-ranged that the interaction can be considered fairly similar to that present between macroparticles in colloidal suspensions and protein solutions. Theoretical approaches are found to give a reasonably accurate description of the physical properties of the system at high lambda's. The relative position of the sublimation vs. the liquid-vapor binodal line, known from computer simulations to play a crucial role in the onset of crystallization in protein solutions, seems qualitatively reproducible. We suggest on the basis of our results the possibility to extend such investigations to more realistic models of protein solutions, so to take into account the true multicomponent nature of these fluids, a physical situation whose description still challenges the currently available computer simulation capabilities.