For 4 compounds, binding constants could be determined using BLI using PaFabF C164A (Table ). The most potent compound 124 had a binding affinity of 65 µM which translates to a ligand efficiency (LE) of 0.39 kcal/mol/heavy atom. The two other investigated carboxylic acids (122 and 123) had weaker affinities with 840 and 880 µM, respectively.