CHEMBL5739384

Fluorescence Assay for Recombinant Human (RH) DPP1: The activity of DPP1 was determined by measuring the enzymatic release of amino methyl 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 10 μl at rt. The assay conditions contained the following: 25 mM piperazine buffer pH 5.0; 50 mM NaCl, 5 mM DTT; 0.005 (v/v) Triton X-100; 50 μM H-Gly-Arg-AMC and 96.4 pM rhDPP1—Potential inhibitors were diluted in DMSO to generate 100× of the final assay concentration. The compounds were tested at 10 concentrations with half-log dilution steps (highest concentration typically 1 μM) and with a final DMSO concentration of 1% (v/v). Routinely, inhibitors were pre-incubated with rhDPP1 for 30 min prior to the addition of the peptide substrate to start the reaction for a further 30 min. After incubation the plates were read in a fluorescence plate reader using the above emission and excitation wavelengths. The pIC₅₀were determined using a 4-paramater logistic equation in a non-linear curve fitting routine (Smartfit, Genedata Screener®). 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 and 1% (v/v) DMSO was used as a negative control in the assay.