Assay Method Information

Assay Name:  Scintillation Proximity Assay (SPA)
Description:  The PDE4A3, PDE4B1, PDE4C1 and PDE4D3 assays use the Scintillation Proximity Assay (SPA) technology to measure the inhibition of human recombinant PDE4A1, PDE4B3, PDE4C1, and PDE4D3 enzyme activity by compounds in vitro. The PDE4A1, PDE4B3, PDE4C1, and PDE4D3 assays are run in parallel using identical parameters, except for the concentration of enzyme (80 pM PDE4A3, 40 pM PDE4B3, 40 pM PDE4C1 and 10 pM PDE4D). The assays are performed in a 384-well format with 50 uL assay buffer (50 mM TRIS pH7.5; 1.3 mM MgCl2; 0.01% Brij) containing enough PDE4A3, PDE4B1, PDE4C1, and PDE4D to convert 20% of substrate (1 μM cAMP consisting of 20 nM 3H-cAMP+980 uM cold cAMP) and a range of inhibitors. Reactions are incubated for 30 min at 25° C. The addition of 20 uL of 8 mg/ml yitrium silicate SPA beads (Perkin Elmer) stops the reaction. The plates are sealed (TopSeal, Perkin Elmer) and the beads are allowed to settle for 8 hrs, after which they are read on the Trilux Microbeta overnight.
Affinity data for this assay
 

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