| Assay Method Information | |
| | Biochemical Assay |
| Description: | The ability of compounds to inhibit CDK7 kinase activity was tested in a TR-FRET assay using 5 nM of CDK7/CycH/MNAT1 obtained from Invitrogen, USA. Test compounds were pre-incubated with the kinase at room temperature for 60 min. After the incubation, substrate mix [100 nM Ultra-light MBP (Perkin Elmer, USA) and 1 mM ATP (Sigma)] was added. The above reaction was stopped by the addition of 40 mM EDTA after 60 minutes of kinase reaction. 1 nM Eu-labelled antiphospho-MBP antibody [Perkin Elmer, USA] was added, mixed well and the fluorescence emission at 615 nm and 665 nm [excitation at 340 nm] was measured. The final DMSO concentration in the assay was 1%. For IC50 determination, appropriate concentrations were made by ⅓rd serial dilutions of 10 mM DMSO stock solution of test compound. All the fluorescence measurements were made in a Victor 3 Multilabel Counter [Perkin Elmer, USA]. The IC50 was determined by fitting the dose response data to sigmoidal curve fitting equation using GraphPad Prism software V5. To identify compounds that inhibit CDK7 irreversibly, time depended inhibition studies were carried by pre-incubating compound with the enzyme at three time points (20, 60 and 180 min) and carrying out assay as described above. |
| Affinity data for this assay | |
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