2.5 Anchor residues
Anchor residues and their ΔSASA (solvent accessible surface area) were calculated for the both PPI and PepPI benchmark datasets from ANCHOR webserver [13]. ΔSASA is the change in the solvent accessible surface area for the side-chain upon binding. The program also estimates the contribution of side-chain to the binding free energy. ΔSASA and binding free energy were calculated for all interface residues. Anchor residues were identified that burry the solvent accessible surface area, ΔSASA ≥ 100 Å2 upon binding.
Results and Discussion
Protein-protein and protein-peptide benchmark dataset having 134 and 50 dimer complexes, respectively, were used for calculations and analysis. To identify the hotspots, all interface residues of both partner chains in the complex were mutated to alanine and relative binding affinity (∆∆G) values were calculated upon mutation of all these 184 complexes. Ala scan was carried out using Bioluminate residue scanning module [37-38]. The positive value of ∆∆G indicates loss in binding affinity upon mutation and suggest quantitatively the importance of the particular residue. A negative value refers to the gain in binding affinity indicating that the mutant binds better.