| Assay Method Information | |
| | MKNK1 Kinase Assay |
| Description: | MKNK1-inhibitory activity of compounds of the present invention was quantified employing the MKNK1 TR-FRET assay as described in the following paragraphs. A recombinant fusion protein of Glutathione-S-Transferase (GST, N-terminally) and human full-length MKNK1 (amino acids 1-424 and T344D of accession number BAA 19885.1), expressed in insect cells using baculovirus expression system and purified via glutathione sepharose affinity chromatography, was purchased from Carna Biosciences (product no 02-145) and used as enzyme. As substrate for the kinase reaction the biotinylated peptide biotin-Ahx-IKKRKLTRRKSLKG (C-terminus in amide form) (SEQ ID: 1) was used which can be purchased e.g. form the company Biosyntan (Berlin-Buch, Germany).For the assay 50 nL of a 100 fold concentrated solution of the test compound in DMSO was pipetted into a black low volume 384 well microtiter plate (Greiner Bio-One, Frickenhausen, Germany), 2 μL of a solution of MKNK1 in aqueous assay buffer [50 mM HEPES pH 7.5, 5 mM magnesium chloride, 1.0 mM dithiothreitol, 0.005% (v/v) Nonidet-P40 (Sigma)] was added and the mixture was incubated for 15 min at 22° C. to allow pre-binding of the test compounds to the enzyme before the start of the kinase reaction. Then the kinase reaction was started by the addition of 3 μL of a solution of adenosine-tri-phosphate (ATP, 16.7 μM=>final conc. in the 5 μL assay volume is 10 μM) and substrate (0.1 μM=>final conc. in the 5 μL assay volume is 0.06 μM) in assay buffer and the resulting mixture was incubated for a reaction time of 45 min at 22° C. The concentration of MKNK1 was adjusted depending of the activity of the enzyme lot and was chosen appropriate to have the assay in the linear range, typical concentrations were in the range of 0.05 μg/mi. The reaction was stopped by the addition of 5 μL of a solution of TR-FRET detection reagents (5 nM streptavidine-XL665 [Cisbio Bioassays, Codolet, France] and 1 nM anti-ribosomal protein 56 (pSer236)-antibody from Invitrogen [#44921G] and 1 nM LANCE EU-W1024 labeled ProteinG [Perkin-Elmer, product no. AD0071]) in an aqueous EDTA-solution (100 mM EDTA, 0.1% (w/v) bovine serum albumin in 50 mM HEPES pH 7.5).The resulting mixture was incubated for 1 h at 22° C. to allow the formation of complex between the phosphorylated biotinylated peptide and the detection reagents. Subsequently the amount of phosphorylated substrate was evaluated by measurement of the resonance energy transfer from the Eu-chelate to the streptavidine-XL. Therefore, the fluorescence emissions at 620 nm and 665 nm after excitation at 350 nm were measured in a TR-FRET reader, e.g. a Rubystar (BMG Labtechnologies, Offenburg, Germany) or a Viewlux (Perkin-Elmer). The ratio of the emissions at 665 nm and at 622 nm was taken as the measure for the amount of phosphorylated substrate. The data were normalised (enzyme reaction without inhibitor=0% inhibition, all other assay components but no enzyme=100% inhibition). Usually the test compounds were tested on the same microtiterplate in 11 different concentrations in the range of 20 μM to 0.1 nM (20 μM, 5.9 μM, 1.7 μM, 0.51 μM, 0.15 μM, 44 nM, 13 nM, 3.8 nM, 1.1 nM, 0.33 nM and 0.1 nM, the dilution series prepared separately before the assay on the level of the 100 fold concentrated solutions in DMSO by serial 1:3.4 dilutions) in duplicate values for each concentration and IC50 values were calculated by a 4 parameter fit. |
| Affinity data for this assay | |
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