CHEMBL5736890

Inhibition Assay: PDE1A, PDE1B and PDE1C assays were performed as follows: the assays was performed in 60 uL samples containing a fixed amount of the PDE1 enzyme (sufficient to convert 20-25% of the cyclic nucleotide substrate), a buffer (50 mM HEPES pH 7.6; 10 mM MgCl2; 0.02% Tween20), 0.1 mg/ml BSA, 15 nM tritium labeled cAMP and varying amounts of inhibitors. Reactions were initiated by addition of the cyclic nucleotide substrate, and reactions were allowed to proceed for 1 hr at room temperature before being terminated through mixing with 20 uL (0.2 mg) yttrium silicate SPA beads (PerkinElmer). The beads were allowed to settle for 1 hr in the dark before the plates were counted in a Wallac 1450 Microbeta counter. The measured signals were converted to activity relative to an uninhibited control (100%) and IC50 values were calculated using XIFit (model 205, IDBS).