Overall, HetPCM with ε nonp = 10 is in better agreement with the homogeneous PCM representation with ε s = 78.4 across all three metrics investigated for these protein systems as compared to the HetPCM with ε nonp = 4. This behavior highlights the diminishing sensitivity of the model to differences in dielectric constant as the values approach those of bulk water, effectively mirroring a homogeneous representation. At higher dielectric constants, the effects of using dielectric boundary conditions become saturated, and the differences between internal and external dielectric environments are less pronounced. This convergence suggests that the choice of dielectric constant within a reasonable range may not significantly impact the predictions for solvation free energies or pK a values. These findings emphasize the importance of using a PCM to improve the accuracy of cluster-QM enzyme models, while demonstrating a range of ε nonp values within which the results are not too sensitive to the specific choice.