Non-polar contribution to solvation energy from Born models:
Solvation energy contribution to protein-ligand binding conceptually consists of two different contributions. The first one is collective in nature, comes from the long range interaction of the molecules charges with polar water molecules. The other comes mostly from the short range interactions of the molecules in question with the adjacent layer of the water molecules.
The long range part can be, to a certain extent, be modeled within a continuous electrostatics framework. Recently we have posted a number of improvements to commonly used Generalized Born models. Let us show that GB models may naturally have a good built-in approximation for the surface accessible area for the non-polar contribution calculations.
To do that we take FSBE model as the example and suggest the following equation for the surface area of a molecule:
where
is a coefficient, 
are the surface tensions associated with the atom types, 
are the radii of the ions and 
are the Born radii defined according to the model settings, e.g.
The results of the model surface area differences for 230 protein ligand complexes (the model vs. exact surface data) are presented on the graph. The numbers show an impressive correlation with
.
The surface area requires the same power of the Born radii for the evaluation and thus can be implemented both numerically accurate and computationally efficient.
