Assay Method Information

Assay Name:  PRMT5 Biochemical Assay
Description:  The assays were all performed in a buffer consisting of 20 mM Bicine (pH=7.6), 1 mM TCEP, 0.005% BSG, and 0.002% Tween20, prepared on the day of use. Compounds in 100% DMSO (1 ul) were spotted into a polypropylene 384-well V-bottom plates (Greiner) using a Platemate Plus outfitted with a 384-channel head (Thermo Scientific). DMSO (1 ul) was added to Columns 11, 12, 23, 24, rows A-H for the maximum signal control and 1 ul of SAH, a known product and inhibitor of PRMT5/MEP50, was added to columns 11, 12, 23, 24, rows I-P for the minimum signal control. A cocktail (40 ul) containing the PRMT5/MEP50 enzyme and the peptide was added by Multidrop Combi (Thermo-Fisher). The compounds were allowed to incubate with PRMT5/MEP50 for 30 min at 25 degrees Celsius, then a cocktail (10 ul) containing 3H-SAM was added to initiate the reaction (final volume=51 ul). The final concentrations of the components were as follows: PRMT5/MEP50 was 4 nM, 3H-SAM was 75 nM, peptide was 40 nM, SAH in the minimum signal control wells was 100 uM, and the DMSO concentration was 1%. The assays were stopped by the addition of non-radioactive SAM (10 ul) to a final concentration of 600 uM, which dilutes the 3H-SAM to a level where its incorporation into the peptide substrate is no longer detectable. 50 ul of the reaction in the 384-well polypropylene plate was then transferred to a 384-well Flashplate and the biotinylated peptides were allowed to bind to the streptavidin surface for at least 1 hour before being washed three times with 0.1% Tween20 in a Biotek ELx405 plate washer. The plates were then read in a PerkinElmer TopCount plate reader to measure the quantity of 3H-labeled peptide bound to the Flashplate surface, measured as disintegrations per minute (dpm) or alternatively, referred to as counts per minute (cpm).
Affinity data for this assay
 

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