CHEMBL5733670

Fluorescence Assay A1 for Recombinant Human (RH) DPP1: The activity of DPP1 was determined by measuring the enzymatic release of aminomethyl coumarin (AMC) from the peptide substrate (H-Gly-Arg-AMC), which leads to an increase in fluorescence intensity at λex=350 nm and λem=450 nm. The assay was carried out in black 384 well plates in a final volume of 50 μl at 22° C. The assay conditions contained the following: 25 mM piperazine buffer pH 5.0; 50 mM NaCl, 5 mM DTT; 0.01% (v/v) Triton X-100; 100 μM H-Gly-Arg-AMC and rhDPP1 (˜50 pM). Potential inhibitors were made up in DMSO and then diluted in the assay to give a final concentration of not exceeding 1% (v/v) DMSO. A 10-point half-log dilution series of the inhibitors (highest concentration typically 10 μM) was tested and the pIC50 determined using a 4-paramater logistic equation in a non-linear curve fitting routine. A standard DPP1 inhibitor, 4-amino-N-[(1S)-1-cyano-2-(4′-cyanobiphenyl-4-yl)ethyl]tetrahydro-2H-pyran-4-carboxamide (WO2010/128324, Ex. 3) was used as a positive control in the assay. Routinely, inhibitors were pre-incubated with rhDPP1 for 30-60 min prior to the addition of the peptide substrate to start the reaction for a further 60 min at 22° C. After that the plates were immediately read in a fluorescence plate reader using the above emission and excitation wavelengths [modified from Kam, CM, Gotz, MG, Koot, G, McGuire, M J, Thiele, D L, Hudig, D & Powers, J C (2004). Arch Biochem Biophys, 427, 123-134 & McGuire, M J, Lipsky, P E & Thiele, D L (1992). Arch Biochem Biophys, 295, 280-288].