  An understanding of the hydrophobicity of complex heterogeneous molecular
assemblies is crucial to characterize and predict interactions between
biomolecules. As such, uncovering the subtleties of assembly processes hinges
on an accurate classification of the relevant interfaces involved, and much
effort has been spent on developing so-called "hydrophobicity maps." In this
work, we introduce a novel electrostatics-based mapping of aqueous interfaces
that focuses on the collective, long-wavelength electrostatic response of water
to the presence of nearby surfaces. In addition to distinguishing between
hydrophobic and hydrophilic regions of heterogeneous surfaces, this
electrostatic mapping can also differentiate between hydrophilic regions that
polarize nearby waters in opposing directions. We therefore expect this
approach to find use in predicting the location of possible water-mediated
hydrophilic interactions, in addition to the more commonly emphasized
hydrophobic interactions that can also be of significant importance.
