Assay Method Information | |
| Fluorescence Polarisation (FP) Homogeneous Assay |
Description: | USP7 activity was monitored in a fluorescence polarisation (FP) homogeneous assay using the isopeptide ubiquitin-Lys-TAMRA substrate (U-558, Boston Biochem). Full-length USP7 was purchased from Boston Biochem (His6-USP7FL, E-519). Unless otherwise stated, all other reagents were purchased from Sigma-Aldrich. Enzymatic reactions were conducted in black flat-bottom polystyrene 384-well plates (Nunc) and 15 μL total volume. USP7 (2.5 nM, 5 μL) was incubated in assay buffer (50 mM HEPES (pH 7.2), 150 mM NaCl, 0.5 mM EDTA, 5 mM DTT, 0.05% BSA (w/v), 0.05% CHAPS) in the presence or absence of inhibitor (5 μl). Inhibitors were stored as 10 mM DMSO stocks in an inert environment (low humidity, dark, low oxygen, room temperature) using a Storage Pod System and serial dilutions were prepared in buffer just prior to the assay (from 200 to 0.1 μM, 8 dp curve). Following incubation at room temperature for 30 min, the enzymatic reactions were initiated by dispensing the Ub substrate (250 nM, 5 μL). FP was measured every 15 min over a period of 1.5 h (within the linear range of the assay) using a Synergy 4 plate reader (BioTek) exciting at 530 nm and measuring the amount of parallel and perpendicular light at 575 nm. |
Affinity data for this assay | |
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