In Figure we show the titration curves for AlaAspAla, AlaGluAla and AlaHisAla tripeptides, obtained from simulations with the modified all-atom CHARMM36 46 and coarsegrained Martini 2.0 force fields. Fitting the deprotonated fractions as a function of pH value to the Henderson-Hasselbalch equation (dashed lines in Figure ) yields pK a values for the tripeptides that are within 0.1 pK a units from the reference values. Comparing the titration curves obtained with the Martini 2.0 force field in our implementation to those computed with the constant pH approach developed explicitly for this coarse-grained model, our results suggest a much better agreement with experiment than the latter. We attribute this difference to the more sophisticated explicit treatment of proton-like particles in the Martini constant pH approach. The rather good agreement between the titration curves obtained for both force fields on the one hand and experiment on the other hand suggests that our implementation has little to no dependency on the force field, in line with the GROMACS philosophy of supporting a wide range of popular force fields.