  The interaction between surface patches of proteins with different surface
properties has a vital role to play driving conformational changes of proteins
in different salt solutions. We demonstrate the existence of ion-specific
attractive double-layer forces between neutral hydrophobic and hydrophilic
surfaces in the presence of certain salt solutions. This is done by solving a
generalized Poisson-Boltzmann equation for two unequal surfaces. In the
calculations we utilize parameterized ion-surface-potentials and
dielectric-constant-profiles deduced from recent non-primitive-model molecular
dynamics (MD) simulations that account partially for molecular structure and
hydration effects.
