product is stable at ≤ ‑70° C for up
to 1 year from the date of receipt. For optimal storage, aliquot into smaller
quantities after centrifugation and store at recommended temperature. Avoid repeated freeze-thaw cycles.
Supplied in 50 mM Tris-HCl, pH 7.5, 150 mM NaCl, 0.25 mM DTT, 0.1 mM EGTA, 0.1 mM EDTA, 0.1 mM PMSF, 25% glycerol.
>70%, by SDS-PAGE under reducing conditions and visualized by Colloidal Coomassie® Blue stain at 5 μg per lane
Active Kinase - Active Chk1 (0.1 μg/μL) diluted with Kinase Dilution Buffer to the concentrations shown in Figure 2. Note: These are suggested working dilutions. Optimal dilutions should be determined by each laboratory for each application.
Kinase Assay Buffer I, pH 7.2 - 25 mM MOPS, 12.5 mM beta -glycerolphosphate, 25 mM MgCl2, 5 mM EGTA, 2 mM EDTA. Add 0.25 mM DTT to the Kinase Assay Buffer prior to use.
Kinase Dilution Buffer, pH 7.2 - Kinase Assay Buffer I diluted at a 1:4 ratio (5-fold dilution) with distilled or deionized water. 10 mM ATP Stock Solution - Prepare the ATP Stock Solution by dissolving 55 mg of ATP in 10 mL of Kinase Assay Buffer I.
[33P]-ATP Assay Cocktail - Prepare 250 μM [33P]-ATP Assay Cocktail in a designated radioactive work area by combining 150 μL of 10 mM ATP Stock Solution, 100 μL of [33P]-ATP (1 mCi/100 μL), and 5.75 mL of Kinase Assay Buffer I.
Substrate - Chk-tide synthetic peptide substrate (KKKVSRSGLRSPSMPENLNRPR) diluted in distilled or deionized water to a final concentration of 1 mg/mL.
Thaw the [33P]-ATP Assay Cocktail in a shielded container in a designated radioactive work area.
Thaw the Active Chk1, Kinase Assay Buffer I, Substrate, and Kinase Dilution Buffer on ice
In a pre-cooled microfuge tube, add the following reaction components bringing the initial reaction volume up to 20 μL. a. Diluted Active Chk1: 10 μL b. Substrate (1 mg/mL Stock Solution): 5 μL
Set up the blank control as outlined in step 3, excluding the addition of the substrate. Replace the substrate with an equal volume of distilled or deionized water.
Initiate the reaction by the addition of 5 μL [33P]-ATP Assay Cocktail, bringing the final volume up to 25 μL. Incubate the mixture in a water bath at 30 °C for 15 minutes.
After the 15 minute incubation period, terminate the reaction by spotting 20 μL of the reaction mixture onto individual pre-cut strips of phosphocellulose P81 paper.
Air dry the pre-cut P81 strip and sequentially wash in a 1% phosphoric acid solution (dilute 10 mL of phosphoric acid and make a 1 liter solution with distilled or deionized water) with constant gentle stirring. It is recommended that the strips be washed a total of three times for approximately 10 minutes each.
Count the radioactivity on the P81 paper in the presence of scintillation fluid in a scintillation counter.
Determine the corrected cpm by removing the blank control value (see step 4) for each sample and calculate the kinase specific activity as outlined below:
Calculation of [33P]-ATP Specific Activity (SA) (cpm/pmol) Specific Activity (SA) = cpm for 5 μL [33P]-ATP/pmol of ATP (in 5 μL of a 250 μM ATP stock solution; i.e. 1250 pmol)
Calculation of Kinase Specific Activity (SA) (pmol/minutes/μg or nmol/minutes/mg) Corrected cpm from reaction / [(SA of 33P-ATP in cpm/pmol) x (Reaction time in minutes) x (Enzyme amount in μg or mg)] x [(Reaction volume) / (Spot Volume)]
This product is produced by and ships from R&D Systems, Inc., a Bio-Techne brand.
Alternate Names for Recombinant Human Active Chk1 Protein, CF
Checkpoint, S. pombe, homolog of, 1
CHK1 (checkpoint, S.pombe) homolog
CHK1 checkpoint homolog (S. pombe)
CHK1serine/threonine-protein kinase Chk1
Chk1 is a 56 kDa Serine/Threonine protein kinase that was originally identified in fission yeast to play a role in activation of the DNA damage checkpoint in the G2 phase of the cell cycle (1). Chk1 appears to function downstream of several of the known fission yeast checkpoint gene products, including that encoded by Rad3, a gene with sequence similarity to the ATM gene mutated in patients with ataxia telangiectasia (2).
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