CHEMBL5737602

Enzymatic Activity Assay: The enzymatic activity of Wild Type HPK1 (MAP4K1) Kinase was measured in the presence or absence of an inhibitor compound of the present disclosure by preparation of a reaction mixture containing a fluorescein tagged peptide (2 micromolar final concentration), ATP (Adenosine Triphosphate, 500 micromolar final concentration) and Wild Type kinase (6 nM final concentration) in a buffer system comprising 50 mM HEPES (Buffer), 3 mM MgCl2, 5% w/v Trehalose, 0.01% Brij 35 (Detergent), 0.1% Pluronic F127 (Surfactant), 0.1 mM EDTA (Ethylenediaminetetraacetic acid), 0.1 mM EGTA (ethylene glycol-bis(β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid) and 1 mM DTT (Dithiothreitol) and at a pH of 7.4. The reactions were quenched by the addition of EDTA to a final concentration of 25 mM. A Caliper EZ reader was used to measure the extent of substrate to product conversion.The peptide substrate used in the HPK1 assay was designed based on the amino acid sequence surrounding serine residue 376 of SLP76-Lymphocyte cytosolic protein 2 (a known intracellular substrate of HPK1). This sequence SSFPQSAsLPPYFSQ was modified as follows for use in Caliper assays of HPK1: the serine residues on either side of serine 376 were replaced with alanine, three lysine residues were added at the N-terminus and a fluorescein tag (FAM) was attached to the C-terminus to produce the sequence, FAM-FPQAAsLPPYFAKKK.