The following three figures are modified from Thorn and Bogan 1998, and more information about these results can be found there.

Binding free energy of sidechains is poorly correlated with the change in buried surface area. Protein-protein entries in ASEdb as of November 1, 2000 were selected for those at the interface (delta ASA > 0) and not buried in the monomer (monomer ASA > 10). Although free energies of binding are well correlated with buried surface area for interfaces as a whole, it can be seen that this does not hold at the level of individual sidechains.

Sequestration of residues from bulk solvent is a necessary condition for large energy contributions. The same set of residues as above was selected from ASEdb, except change in binding free energy is plotted against solvent accessibility in the complex. This shows that a high degree of burial is a necessary, but not sufficient, condition for a large energetic contribution to binding.

Amino acid preferences in hotspots. For each amino acid, the frequency of that amino acid in the database as a whole and in the subset with binding energies > 2 kcal/mol was determined. The ratio of these quantities gives the fold enrichment in hotspots. It can be seen that the distribution is highly non-random, with Trp, Tyr, and Arg being significantly enriched in hotspots.