Enzymatic Assay: The assay is carried out in 1.5 ml Eppendorf tubes comprising 40 mM of Tris-HCl (pH 7.5), 15 mM of MgCl2, 1 mM of EGTA, 0.5 mg/ml of bovine serum albumin, 0.063 uCi of [3H]-cAMP (corresponding to a cAMP concentration of between 15 and 25 nM), 10 uM of rolipram and PDE7 in a final volume of 100 ul. The assay is carried out in the absence (control sample) or in the presence (treated sample) of the compounds tested as PDE7 inhibitors. The final concentration of DMSO in the assay is 2%. The reaction is initiated by addition of enzyme and the samples are maintained at ambient temperature for 30 minutes. The enzymatic dilution is adjusted so as to obtain a degree of conversion of 10 to 15%. The enzymatic reaction is halted by immersion of the stoppered Eppendorf tubes in a water bath at 100C. for 3 minutes. Blanks (reaction halted immediately after addition of the enzyme) are included in each experiment.
Enzymatic Assay: By using for PDE8 an enzymatic assay equivalent to that described for PDE7. PDE7 Enzymatic Assay: The assay is carried out in 1.5 ml Eppendorf tubes comprising 40 mM of Tris-HCl (pH 7.5), 15 mM of MgCl2, 1 mM of EGTA, 0.5 mg/ml of bovine serum albumin, 0.063 uCi of [3H]-cAMP (corresponding to a cAMP concentration of between 15 and 25 nM), 10 uM of rolipram and PDE7 in a final volume of 100 ul. The assay is carried out in the absence (control sample) or in the presence (treated sample) of the compounds tested as PDE7 inhibitors. The final concentration of DMSO in the assay is 2%. The reaction is initiated by addition of enzyme and the samples are maintained at ambient temperature for 30 minutes. The enzymatic dilution is adjusted so as to obtain a degree of conversion of 10 to 15%. The enzymatic reaction is halted by immersion of the stoppered Eppendorf tubes in a water bath at 100C. for 3 minutes.