| Assay Method Information | |
| | Biological Assay |
| Description: | Assay Principle: The PDE reaction cleaves cAMP to AMP. The IMAP system (Molecular Device) using fluorescence polarization (FP) as detection principle was used to measure enzyme activity. A fluorescent labeled cAMP was used as substrate for the reaction, generating a labeled AMP. The fluorescent AMP binds specifically to the large M(III)-based nano-particles which reduces the rotational speed of the substrate and thus increases its polarization.</p><p id="h-0016" num="0000">Detailed Method:The inhibition of PDE 2A or 10 enzyme activity was assessed using IMAP-Phosphodiesterase-cAMP fluorescence labeled substrate (Molecular Devices, Order No. R7506), IMAP TR-FRET screening express (Molecular Devices, Order No. R8160, the TR-FRET component will not be used) and PDE 2A or PDE10 protein expressed upon baculovirus infection in SF9 cells. The cells were incubated after infection for 3 days and protein production was confirmed by Western Blot. The cells were collected by centrifugation and the pellet frozen in liquid nitrogen before it was resuspended in PBS containing 1% Triton X-100 and protease inhibitors. After 45 min incubation on ice, the cell debris was removed by centrifugation (13.000 rpm, 30 min). Since SF 9 cells do not express cAMP hydrolyzing enzymes to a high extent, no further purification of the protein was needed. All reactions were performed in 384 well plates, Perkin Elmer black optiplates and IMAP reaction buffer with 0.1% Tween20 (kit component). Compounds were serial diluted in DMSO. With an intermediate dilution step with reaction buffer DMSO concentration was reduced to achieve 1% DMSO in the assay reaction. Setup of the assay started with 10 μl enzyme ( 10 ng/well, depending on prep. batch), 5 μl compound, reaction was started by addition of 5 μl labeled cAMP (30 nM, final concentration), immediately mixed for 15 seconds on a Eppendorf mixmate (2000 rpm) followed by an incubation at room temperature for 90 minutes in the dark. Reaction is stopped by adding of 60 μl binding buffer for FP/cAMP (kit component). After at least 90 min of further incubation (room temperature, dark) the assay was measured at 485 nm excitation/525 nm emission in an Envision multilabel reader (PerkinElmer).Each assay plate contained wells with vehicle controls (1% DMSO) for the measurement of non-inhibited reaction (=100% control) and wells without enzyme as 0% controls. |
| Affinity data for this assay | |
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