Potency characterization of aminopeptidase N (APN) inhibitors. Dose-response curves for the panel of 8 metalloprotease inhibitors (MPIs) using (a) the generic fluorescence polarization (FP) competition assay for metalloproteinases and (b) the APN functional assay. Each data point corresponds to the average of the results of 3 separate experiments, and error bars represent the standard deviation of the signal in the 3 experiments. IC50s in the FP assay: TAPI-0, 0.9 μM; actinonin, 1.0 μM; GM6001, 1.4 μM; NNGH, 2.2 μM; Z-PLG-NHOH, 12 μM; bestatin, 46 μM. IC50s in the functional assay: TAPI-0, 7.7 nM; actinonin, 18 nM; GM6001, 35 nM; NNGH, 82 nM; Z-PLG-NHOH, 1.2 μM; bestatin, 15 μM.