CHEMBL3887972

Fluorescence Resonance Energy Transfer (FRET) Assay: The enzyme inhibitory activities of compounds disclosed herein were determined by fluorescence resonance energy transfer (FRET) using synthetic peptides labelled with both donor and acceptor fluorophores (Z-LYTE, Invitrogen Ltd., Paisley, UK). Recombinant, phosphorylated p38 MAPKγ (MAPK12: Invitrogen) was diluted in HEPES buffer, mixed with the test compound at the desired final concentrations and incubated for 2 hr at RT. The FRET peptide (2 μM) and ATP (100 μM) were added to the enzyme/compound mixture and incubated for 1 hr. Development reagent (protease) was added for 1 hr prior to detection in a fluorescence microplate reader (Varioskan® Flash, ThermoFisher Scientific). The site-specific protease cleaves non-phosphorylated peptide only and eliminates the FRET signal. Phosphorylation levels of each reaction were calculated using the ratio of coumarin emission (donor) over fluorescein emission (acceptor) for which high ratios indicate high phosphorylation and low rat