Recombinant Human Active MEK2 Protein, CF

• Active Kinase - Active MEK2 (0.1 μg/μL) diluted with Kinase Dilution Buffer. Note: These are suggested working dilutions. Optimal dilutions should be determined by each laboratory for each application.
• Kinase Assay Buffer I - 25 mM MOPS, pH 7.2, 12.5 mM beta -glycerolphosphate, 25 mM MgCl₂, 2 mM EDTA. Add 0.25 mM DTT to the Kinase Assay Buffer prior to use.
• Kinase Dilution Buffer - Kinase Assay Buffer diluted at a 1:4 ratio (5X dilution) with 50 ng/μL BSA solution.
• 10 mM ATP Stock Solution - Prepare the ATP Stock Solution by dissolving 55 mg of ATP in 10 mL of Kinase Assay Buffer. Store 200 μL aliquots at ≤ -20 °C.
  
• [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. Store 1.0 mL aliquots at ≤ -20 °C.
• Substrate - Inactive ERK2 was activated using MEK2 and a Myelin Basic Protein (MBP) diluted in 100 mM MOPS, pH 6.5 buffer to a final concentration of 0.2 mg/mL and 1.0 mg/mL, respectively.

1. Thaw the Active MEK2, Kinase Assay Buffer I, and inactive ERK2 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 MEK2: 5 μL
   b. Inactive ERK2 (0.2 μg/μL): 10 μL
   c. Kinase Assay Buffer: 5 μL
2. Start the reaction with the addition of 5 μL ATP (250 μM) and incubate in a water bath at 30 °C for 15 minutes.
3. After the 15 minute incubation, remove 5 μL and add it to the following reaction components on ice, bringing the initial reaction volume up to 20 μL
   a. Reaction Mixture: 5 μL
   b. MBP Substrate (1 mg/mL; on ice): 5 μL
   c. Distilled or deionized water (on ice): 10 μL
4. 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.
5. Thaw the [³³P]-ATP Assay Cocktail in a shielded container in a designated radioactive work area. Initiate the reaction with 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.
6. After the 15 minute incubation, terminate the reaction by spotting 20 μL of the reaction mixture onto individual pre-cut strips of phosphocellulose P81 paper.
7. Air dry the pre-cut P81 strip and sequentially wash in a 1% phosphoric acid solution (add 10 mL of phosphoric acid to 990 mL of 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.
8. Count the radioactivity on the P81 paper in the presence of scintillation fluid in a scintillation counter.
9. Determine the corrected cpm by subtracting 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)]

Scientific Data

SDS-PAGE View Larger

The approximate molecular weight is 71 kDa and the purity is > 80%.