Evaluation of the ABCG2 charge model in protein–ligand binding affinity calculations

Accurate binding free energy prediction is vital for drug design, motivating the assessment of new force field models. Here, we evaluate the ABCG2 charge model with nonequilibrium alchemical free energy simulations. GAFF2/ABCG2 achieves higher hydration free energy accuracy, but does not outperform GAFF2/AM1-BCC for protein–ligand binding free energy. Both charge models show comparable accuracy and compound ranking across targets, highlighting that optimizing a force field for a particular molecular property does not necessarily lead to better performance in other, even closely related, properties.