We considered three SNase dyads and one DJ-1 dyad, resulting in four sets of simulations. SNase simulations were performed at pH values from -1 to 7 with 0.25 pH increments and from 7 to 14 with 0.5 pH increments, while DJ-1 simulations were performed from 0 to 14 with 0.5 pH increments. Regarding SNase, both residues in the dyad (i.e., D21-D19, D21-D40, and D21-D83) were allowed to (de)protonate as a function of pH, which in two cases resulted in non-sigmoidal curves. In the case of DJ-1, we allowed only E18 to titrate, while holding C106 fixed to a protonated or deprotonated state; this resulted in sigmoidal curves.