Assay Method Information

Assay Name:  PDK1 kinase assay
Description:  PDK1 (amino acids 51-359) and AKT2 (amino acids 140-467 fused to PIFtide, amino acids EEQEMFRDFDYIADW) were expressed as N-terminally tagged GST fusion proteins in insect cells and purified to homogeneity. Enzyme activity was determined in a coupled PDK1/AKT/FAM-crosstide assay and phosphorylation of FAM-crosstide was determined by standard IMAP protocol (Molecular Devices). For inhibition studies, compounds were titrated 4-fold in DMSO and diluted 40-fold into assay buffer (10 mM Tris HCl pH7.2; 10 mM MgCl2; 0.01% Triton X-100; 1 mM DTT) containing PDK1, AKT2, and FAM-crosstide (final concentrations: 0.75 nM PDK1, 10 nM unphosphorylated AKT2, and 100 nM crosstide substrate). The kinase reaction was initiated by adding ATP to a final concentration of 40 μM of PDK1 and incubated at 25° C. for 30 min. To detect assay product, the kinase reaction was combined with Progressive Binding Solution (1:600 Progressive Binding Reagent, 50% Buffer A, 50% Buffer B, Molecular Devices) in a 1:3 ratio. The mixture was incubated for 2 hours at 25° C. and the plate was scanned on an Analyst AD with excitation at 485 nm and emission at 530 nm. The fluorescence polarization value P is defined by the equation below. The value mP is generated by multiplying the P value for each reaction well by a factor of 1000. The value ΔmP for each well is the mP value for that well minus the mP value for the average negative control. P=(Fpar−Fperp)/(Fpar+Fperp)  Eq.:Where par is fluorescence intensity parallel to the excitation plane; and perp is fluorescence intensity perpendicular to the excitation plane. ΔmP values were plotted as a function of compound concentration and the data were analyzed with a 4-parameter fit using GraphPad Prism software.
Affinity data for this assay
 

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