Electrostatics in proteins and protein-ligand complexes

Accurate computational methods for predicting the electrostatic energies are of major importance for our understanding of protein energetics in general, for computer-aided drug design and in the design of novel biocatalysts and protein therapeutics. Electrostatic energies are of particular importance in applications such as virtual screening, drug design and protein-protein docking due to the high charge densitiy of protein ligands and small-molecule drugs, and the frequent protonation state changes observed when drugs are binding to their protein targets. Therefore, the development of a reliable and fast algorithm for the evaluation of electrostatic free energies, as an important contributor to the overall protein energy function, has been the focus of many scientists for the last three decades. In this review we describe the current state of-the-art in modeling electrostatic effects in proteins and protein-ligand complexes. We focus mainly on the merits and drawbacks of the continuum methodology, and speculate on future directions in refining algorithms for calculating electrostatic energies in proteins using experimental data.