CHEMBL5736610

Enzymatic Activity Assay : The activity of recombinant human PI3Kγ ((aa144-1102)-6His) and PI3Kα, β, δ (6-His(p110-p85α)) was determined by measuring the ADP level after phosphorylation of DiC8-PIP2 using a commercially available ADP-Glo™ kit from Promega. The assay was carried out in white low volume 384 well plates in a final volume of 14 μl at R.T. The assay conditions contained the following: 50 mM Tris buffer pH 7.4, 2.1 mM DTT, 3 mM MgCl2, 0.05% CHAPS, 20 μM ATP, 80 μM DiC8-PIP2 and 1.2 nM PI3Kα, β, γ or 0.6 nM PI3Kδ. 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 0.1 μM for δ or γ and 33 μM for a or 1) was tested and the pIC50 determined using a 4-parameter logistic equation in a non-linear curve fitting routine. Routinely, inhibitors were pre-incubated with 3 μl of enzyme for 15 min prior to the addition of 2 μl substrate mixture for a further 60 min enzyme reaction. The phosphorylation was stopped with the addition of 3 μl ADP-Glo™ reagent (stop solution) followed by a 40 min incubation. Prior to detection 6 μl of ADP-Glo™ Kinase Detection Reagent was added and the plates were read in a micro plate reader using a Luminescence filter. All additions were followed by a short centrifugation step.