The corresponding energy-geometric process is depicted in Figure . In Eq. ( ), ∆G A-B corresponds to the intrinsic PPIs unique to any protein pair that bring the two unbound proteins to the energetically favorite binary state, i.e., the binary state with the lowest free energy, even if ∆G A-B is positive (Figure ). The strength of induced PPIs depends on the interplay between unary (∆G s geo,A + ∆G s geo,B ) and binary perturbation (∆G s geo,AB ). An example of a unary perturbation is the change in the secondary structure upon binding of a molecular glue (Figure ), whereas an example of a binary perturbation is the disruption of native protein-protein contacts by PPI stabilizers (Figure ). ). (E): Statistics of the PPIs from 2619 1/K D values of structurally resolved protein-protein complexes from PDBbind v2019 . c 0 is the standard concentration of 1 molar and K A-B is used here to distinguish the protein-protein affinities from ligand-protein affinities.