It is important to characterize the frequency of interaction between a binding residue and all bound molecules (Percentage of interaction, (PI%)) and what is the energy of interaction (ΔE FMO ) with functional groups on bound ligands. In this sense, interaction energy (ΔE FMO ) and percentage of interaction (PI%) can be considered as key descriptors to label binding site residues according to their accessibility and anchoring features that can influence ligand affinity.