| Assay Method Information | |
| | Biological Assays |
| Description: | The activity of a compound according to the present invention can be assessed by well-known in vitro & in vivo methods. Raf inhibition data provided herein was obtained using the following procedures.In Vitro Raf Activity Determination: The RAF enzymes and the catalytically inactive MEK1 protein substrate were all made in-house using conventional methods. CRAF cDNA was subcloned as full length protein, with Y340E and Y341E activating mutations, into a baculovirus expression vector for Sf9 insect cell expression. h14-3-3 zeta cDNA was subcloned into a baculovirus expression vector for SF9 insect cell expression. Sf9 cells co-expressing both proteins were lysed and subjected to immobilized nickel chromatography and eluted with Imidazole. A second column (StrepII binding column) was used and eluted with desthiobiotin. Protein Tags were removed using Prescission enzyme and the protein was further purified using a flowthrough step to remove tags.C-Raf TR refers to a truncated C-Raf protein, a Δ1-324 deletion mutant. C-Raf FL refers to the full-length C-Raf protein.Full length MEK1 with an inactivating K97R ATP binding site mutation is utilized as a RAF substrate. The MEK1 cDNA was subcloned with an N-terminal (his)6 tag into a vector for E. Coli expression. The MEK1 substrate was purified from E. Coli lysate by nickel affinity chromatography followed by anion exchange. The final MEK1 preparation was biotinylated (Pierce EZ-Link Sulfo-NHS-LC-Biotin) and concentrated.Assay Materials: Assay buffer is 50 mM Tris, pH 7.5, 15 mM MgCl2, 0.01% Bovine Serum Albumin (BSA) and 1 mM dithiothreitol (DTT); Stop buffer is 60 mM ethylenediaminetetraacetic acid (EDTA) and 0.01% Tween 20; b-Raf (V600E), active; biotinylated Mek, kinase dead; Alpha Screen detection kit (available from PerkinElmer , #6760617R); Anti phospho-MEK1/2 (available from Cell Signaling Technology, Inc. #9121); 384 well low volume assay plates (White Greiner plates).Assay conditions: b-Raf (V600E) approximately 4 pM; c-Raf approximately 4 nM; biotinylated Mek, kinase dead approximately 10 nM; ATP 10 μM for BRAF (V600E) and 1 μM for CRAF; Pre-incubation time with compounds 60 minutes at room temperature; Reaction time 1 or 3 hours at room temperature.Assay protocol: Raf and biotinylated Mek (kinase dead) were combined at 2× final concentrations in assay buffer (50 mM Tris, pH 7.5, 15 mM MgCl2, 0.01% BSA and 1 mM DTT) and dispensed 5 ml per well in assay plates (Greiner white 384 well assay plates #781207) containing 0.25 ml of 40× of a Raf kinase inhibitor test compound diluted in 100% DMSO. The plate was incubated for 60 minutes at room temperature. The Raf kinase activity reaction was started by the addition of 5 mL per well of 2×ATP diluted in assay buffer. After 3 hours (b-Raf(V600E)) or 1 hour (c-Raf). The reactions were stopped and the phosphorylated product was measured using a rabbit anti-p-MEK (Cell Signaling, #9121) antibody and the Alpha Screen IgG (ProteinA) detection Kit (PerkinElmer #6760617R), by the addition of 10 mL to the well of a mixture of the antibody (1:2000 dilution) and detection beads (1:2000 dilution of both beads) in Stop/bead buffer (25 mM EDTA, 50 mM Tris, pH 7.5, 0.01% Tween20). The additions were carried out under dark conditions to protect the detection beads from light. A lid was placed on top of the plate and incubated for 1 hour at room temperature, after which the luminescence was read on a PerkinElmer Envision instrument. The concentration of each compound for 50% inhibition (IC50) was calculated by non-linear regression using XL Fit data analysis software. |
| Affinity data for this assay | |
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