Discrete charge patterns, Coulomb correlations and interactions in protein solutions

摘要

The effective Coulomb interaction between globular proteins is calculated asa function of monovalent salt concentration $c_s$, by explicit MolecularDynamics simulations of pairs of model proteins in the presence of microscopicco and counterions. For discrete charge patterns of monovalent sites on thesurface, the resulting osmotic virial coefficient $B_2$ is found to be astrikingly non-monotonic function of $c_s$. The non-monotonicity follows from asubtle Coulomb correlation effect which is completely missed by conventionalnon-linear Poisson-Boltzmann theory and explains various experimental findings.