Abstract
The osmotic virial coefficient of globular protein solutions is calculated as a function of added salt concentration at fixed by computer simulations of the “primitive model.” The salt and counterions as well as a discrete charge pattern on the protein surface are explicitly incorporated. For parameters roughly corresponding to lysozyme, we find that first decreases with added salt concentration up to a threshold concentration, then increases to a maximum, and then decreases again upon further raising the ionic strength. Our studies demonstrate that the existence of a discrete charge pattern on the protein surface profoundly influences the effective interactions and that linear and nonlinear Poisson Boltzmann theories fail for large ionic strength. The observed nonmonotonicity of is compared with experiments. Implications for protein crystallization are discussed.
- Received 21 February 2003
DOI:https://doi.org/10.1103/PhysRevE.67.051404
©2003 American Physical Society