| Assay Method Information | |
| | Kinetic Assay |
| Description: | Assays are performed in 96-well plates in a total volume of 200 μl/well. Compounds are dissolved in dimethylsulfoxide (DMSO) and added to plates in a volume of 10 μl followed by addition of 165 μl of assay mix. Plates are pre-incubated at 25° C. for 15 min and the reactions are initiated by the addition of 25 μl of cAMP followed by thorough mixing. Reaction rates are measured by monitoring the decrease in fluorescence using excitation at 355 nm and emission at 460 nm for a period of 10 min in a fluorescence plate reader. Initial rates (slopes) are determined from linear portions of the progress curves. Final concentrations of assay components are as follows: 50 mM Tris, pH 8, 10 mM MgCl2, 50 mM KCl, 2% DMSO, 5 mM tris(2-carboxyethyl)phosphine (TCEP), 0.4 mM phosphenolpyruvate (PEP), 0.01 mM NADH, 0.04 mM adenosine triphosphate (ATP), 0.004 mM cAMP, 7.5 units myokinase from yeast, 1.6 units pyruvate kinase, 2 units lactate dehydrogenase, and either 0.5 nM human PDE4D7 or 10 nM human PDE4B1. All data are percent normalized relative to controls and are presented as percent inhibition. An inhibitory concentration 50% (IC50) value is calculated by fitting of a sigmoidal dose response curve. Human PDE4D7 contained a mutation of serine 54 to aspartic acid to mimic activation by cAMP-dependent protein kinase A (PKA). Human PDE4B1 contained a corresponding mutation of serine 133 to aspartic acid to also mimic PKA activation. |
| Affinity data for this assay | |
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