Assay Method Information

Assay Name:  iochemical Assay
Description:  Compounds of the invention may be tested for in vitro activity in the following assay: A histone H4 derived peptide is used as substrate (amino acid sequence: Ser-Gly-Arg-Gly-Lys-Gly-Gly-Lys-Gly-Leu-Gly-Lys-Gly-Gly-Ala-Lys-Arg-His-Arg-Lys-Val-NH2). Full-length PRMT5 enzyme (NCBI Reference sequence NP-006100.2) was co-expressed with Hiss-MEP50 in insect cells and purified via Nickel immobilized metal affinity and gel filtration chromatograph.The 6 μL assay reactions are run in Greiner brand black 384-well low volume plates. All reactions contained assay buffer (phosphate buffered saline, 0.01% (v/v) Tween-20, 0.01% (w/v) albumin from chicken egg white, 1 mM dithiothreitol, 200 nM peptide substrate, 1 μM S-Adenosyl methionine, and 15 ng/reaction enzyme, with the enzyme being omitted from negative control reactions. Compounds were added in a volume of 100 nL from dilution series prepared in DMSO, positive and negative control reactions receiving the same volume DMSO without compound. The plates were sealed with adhesive seals and incubated for 4 hours at 37° C. Reaction progress was measured using the Transcreener™ EPIGEN methyltransferase assay (BellBrook Labs, Madison, Wis.) as recommended by the manufacturer. To each reaction 2 μL detection mix were added, containing coupling enzymes, fluorescence polarisation tracer, and AMP antibody. Plates were incubated for 90 min before being read on a PerkinElmer EnVision™ plate reader in fluorescence polarisation mode. IC50 values were obtained from the raw readings by calculating percent inhibition (% I) for each reaction relative to controls on the same plate (% I=(I−CN)/(CP−CN) where CN/CP are the averages of the negative/positive reactions, respectively), then fitting the % I data vs. compound concentration [I] to % I=(A+((B−A)/(1+((C/[I])^D)))) where A is the lower asymptote, B is the upper asymptote, C is the IC50 value, and D is the slope.
Affinity data for this assay
 

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