Inhibition of PLK1 (unknown origin) assessed as remaining activity at 100 uM by radioactive filter binding assay in presence of [33P]-ATP relative to control
Biochemical Assay: The inhibitory activity of putative kinase inhibitors and the potency of selected compounds were determined using a trans-phosphorylation assay.
Biochemical Assay: The inhibitory activity of putative kinase inhibitors and the potency of selected compounds were determined using a trans-phosphorylation assay.Specific peptide or protein substrates are trans-phosphorylated by their specific serine-threonine or tyrosine kinase, in the presence of ATP traced with 33P-gamma-ATP, and in the presence of their own optimal buffer and cofactors.At the end of the phosphorylation reaction, more than 98% cold ATP and radioactive ATP is captured by an excess of the ion exchange dowex resin; the resin then settles down to the bottom of the reaction plate by gravity.Supernatant, containing the phosphorylated substrate, is subsequently withdrawn and transferred into a counting plate, then evaluated by beta-counting.Reagents/Assay Conditions i. Dowex Resin Preparation500 g of wet resin (SIGMA, custom prepared resin DOWEX 1x8 200-400 mesh, 2.5 Kg) are weighed out and diluted to 2 L in 150 mM sodium formate, pH 3.00.The resin is allowed to settle down.
Kinase Inhibition Assay: The compound of Example 39, 2-(1H-indol-5-ylamino)-6-(2,4-difluorophenylsulfonyl)-8-methylpyrido[2,3-d]pyrimidin-7(8H)-one, was subjected to a kinase inhibition assay for the kinases. Compounds were tested in 5 dose IC50 mode with 10-fold serial dilution starting at 10 μM. Staurosporine, a known protein kinase inhibitor, was tested in 5-dose IC50 mode with 3-fold serial dilution starting at 20 μM. Reactions were carried out in 10 μM ATP. The results are shown in Table 5. The results show that the compound of Example 39 is a kinase inhibitor highly selective for the kinase Plk2.