where the sum runs over the N initial native contact residue pairs, r p is the distance between the closest heavy atoms between residues in a pair or the distance between any beads in the case of coarse-grained structures, r p,0 is r p for the starting structure, β is a smoothening factor set to 50 nm -1 , 23 and λ is a calibration factor set to 1.8 for the atomistic simulations and 1.5 for the coarse-grained simulations. In order to quantify the stability of the protein complexes, we also defined a set of interface native contacts which is any residue in the first protein with a native contact to a residue in the second protein, calculated from the initial protein complex structure using a cutoff of 0.45 nm. We quantified the interface native contacts according to equation 4.