| Assay Method Information | |
| | USP7 Assay B (Ubitquin-Rhodamine110 Assay) |
| Description: | Each assay was performed in a final volume of 20 μL in assay buffer containing 20 mM Tris-HCl (pH 8.0, (1M Tris-HCl, pH 8.0 solution; Corning 46-031-CM)), 2 mM CaCl2 (1M Calcium Chloride solution; Sigma #21114) 1 mM GSH (L-Glutathione reduced; Sigma #G4251), 0.01% Prionex (0.22 μM filtered, Sigma #G-0411), and 0.01% Triton X-100. Stock compound solutions were stored at −20° C. as 10 mM in DMSO. Up to 1 month prior to the assay, 2 mM test compounds were pre-dispensed into assay plates (Black, low volume; Corning #3820) and frozen at −20° C. Prestamped assay plates were allowed to come to room temperature on the day of the assay. For the screen, 100 nL of 2 mM was pre-dispensed for a final screening concentration of 10 μM (DMSO(fc)=0.5%). For follow-up studies, 250 nL of an 8-point, 3-fold serial dilution in DMSO was pre-dispensed into assay plates for a final test concentration of 25 μM-11 nM (1.25% DMSO final concentration). Unless otherwise indicated, all follow-up assays were run on triplecate plates. Enzyme (USP7, construct Met (208-1102)-TEV-6*His; Viva Q93009-1) concentration and incubation times were optimized for the maximal signal-to-background while maintaining initial velocity conditions at a fixed substrate concentration. The final concentration of the enzyme in the assay was either 75 or 250 μM. Final substrate (Ub-Rh110; Ubiquitin-Rhodamine 110, R&D Systems (biotechne) #U-555) concentration was 25 nM with [Ub-Rh 110]<<Km. Pre-stamped with compounds were either not preincubated or preincubated with USP7 between 30 to 120 minutes prior to the addition of 10 μL of 2×Ub-Rh110 to compound plates. Plates were incubated stacked for either 23 or 45 minutes at room temperature before fluorescence was read on the Envision (Excitation at 485 nm and Emission at 535 nm; Perkin Elmer) or on the PheraSTAR (Excitation at 485 nm and Emission at 535 nm; BMG Labtech). |
| Affinity data for this assay | |
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