External Set 2, associated with capped amino acids as reported by Fauchère and Pliška 126 , obtained divergent results. On the one hand, the pH-dependent values of N-Acetyl-L-tyrosine amide were predicted with excellent metrics, especially using the LR and SVMP models, because our training set had a representative number of molecules with phenolic groups. On the other hand, in the case of N-acetyl-l-histidine amide, the results were very poor due, at least in part, to the fact that our set had few bases in relation to the acids that best fit Eq. 2, mainly because there was no imidazole fragments present in our set of bases, thus limiting the performance of our models.