| Assay Method Information | |
| | Homogeneous Time Resolved Fluorescence Assay (HTRF) |
| Description: | The assay for the determination of Pim activity is based on the formation of phosphorylated biotinylated-BAD peptide at the Serine 112 residue (S112) and employs HTRF® (homogeneous time resolved fluorescence) technology to detect the product in a 384-well plate format. The phosphorylation of biotinylated-BAD (S112) peptide by full length recombinant Pim-1, Pim-2, or Pim-3 protein was detected with streptavidin:Allophycocyanin (APC) conjugate and a europium (Eu) labeled antibody directed against phosphorylated-BAD (S112). Excitation of Eu by a high energy laser light (337 nm) leads to a transfer of energy to the APC molecule, and results in an emission at 665 nm. The fluorescence is directly proportional to the amount of phosphorylated BAD peptide present in the reaction. Compounds were prepared in DMSO by conducting 3-fold serial dilutions to give a 22-point dosing curve having a high dose of 1 μM. A reference compound was included on each assay plate [Costar 3658] in order to validate that plate; on one plate of every assay run, two additional reference compounds were included. The Reaction Buffer consisted of 45 mM Hepes, pH 7.0, 15 mM NaCl, and 1 mM MgCl. The quench/detection buffer consisted of 50 mM Tris, 100 mM NaCl, 0.05% BSA, 0.1% Tween and 3 mM EDTA. Biotinylated BAD peptide (Biopeptide), 10 mM ATP (Sigma), Labeled p-BAD (S112) mAb (Cell Signalling and Perkin Elmer) [with 0.05% BSA and 2 mM DTT added] streptavidin:Allophycocyanin [Perkin Elmer]. Final concentrations either Pim-1 enzyme [5 pM], or Pim-2 enzyme [0.5 pM], DMSO [1%], BLC BAD (S112) [0.5 μM], ATP [1.5 μM], streptavidin:Allophycocyanin [0.002 mg/mL] and biotinylated-BAD (S112) mAb [100 pM]. Initial incubations were carried out at RT (22° C.) for 30 min for both Pim-1 and for Pim-2. Pim enzyme is added to compound in buffer, and plates are incubated of 30 min. Biotinylated BAD and ATP are added and plates are incubated for 1 h. A mixture of labeled p-BAD (S112) mAb and quench/detection buffer are added and incubated for 2 h. Fluorescence was measured by an HTRF® Envision microplate reader. |
| Affinity data for this assay | |
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