CHEMBL5732348

Caliper Assay: CHK1 kinase activity was measured in a microfluidic assay that monitors the separation of a phosphorylated product from its substrate. The assay was run on an EZ Reader II (Caliper Life Sciences Ltd, Runcorn, UK) using separation buffer (#760367 Caliper LS) containing CR-8 (500 nM, #760278, Caliper LS). An ECHO® 550 (Labcyte Inc) acoustic dispenser was used to generate duplicate 8 pt dilution curves directly into 384 polypropylene assay plates (Greiner Bio-One, Gloucestershire, UK). For each test compound a 50 μM stock concentration in 100% DMSO was used. The total amount of DMSO dispensed per well was 250 nL to give a final assay concentration of 2.5% DMSO and test compound concentrations in the range 0.5-1000 nM. To this assay plate, 6 μL CHK1 (2 nM final concentration, in-house protein preparation), 2 μL peptide 10 (5-FAM-KKKVSRSGLYRSPSMPENLNRPR COOH, 1.5 μM final concentration, #760354 Caliper LS) and 2 μL ATP (90 μM final concentration) all diluted in kinase buffer (HEPES 50 mM, NaN3 0.02%, BSA 0.01%, sodium orthovanadate 0.1 mM, DTT 1 mM, MgCl2 2 mM, Tween 20 0.1%) were added. The plate was sealed and centrifuged (1 minute, 1000 rpm) before incubation for one hour at room temperature. The reaction was stopped by the addition of separation buffer (90 μL). The plate was read on an EZ Reader II, using a 12-sipper chip (760137-0372R, Caliper LS) with instrument settings of 1.5 psi and 1750 ΔV. The percentage conversion of product from substrate was generated automatically and the percentage inhibition was calculated relative to blank wells (containing no enzyme and 2.5% DMSO) and total wells (containing all reagents and 2.5% DMSO).