External ID: HMS1262

Protocol: NEC is stored at -80 degrees at a concentration of 15mg/ml in single use aliquots.

On the day of the screen, 20ul of purified NEC is aliquoted using a Multidrop Combi reagent dispenser into 384 well plates (Corning 3824). 100nl of compound dissolved in DMSO was transferred to each well of the assay plated via pin transfer. The plates (NEC + compound) are incubated at room temperature for 3 hours. Acceptor and donor reagents (CisBio 620/665 pair) are combined then added to each well at 5 microL volumes at a concentration of 8 nM and 80nM respectively. The plates are spun at 1k rpm for 1 min and incubated overnight at 4 degrees, then for one hour the subsequent day at room temperature.

Flourescent measurements are read on the Envision 1 plate reader at ICCB-L. The raw data consists of two fluorescence readings - at 665 nm and 620 nm for the acceptor and donor respectively.

Comment: Data analysis:
The raw data consists of two fluorescence readings - at 665 and 620 nm for the acceptor and donor respectively. The data is processed as a ratio of the emission from the acceptor over the donor (homogeneous time resolved fluorescence ratio). Normalized percent inhibition (NPI) for all experimental wells is calculated based on plate averages for negative and positive control HTRF ratio. Positives are scored as any ratio with a 50% or greater inhibition as compared with the positive control (i.e. NEC + Untagged UL50). To be considered a hit, both replicates need to score as positive. Activity scores are derived from NPI, with 100 = 100% inhibition (> 100% set to 100) and 0 = no inhibition (< 0% set to 0). Note that some compounds with NPI <50% (activity scores < 50) are classified as potential hits based on additional criteria (typically by selecting wells with low ratios compared to other experimental wells on the plate).

External ID: CBX7-Alpha-primary

Protocol: The protocol for the CBX7 AlphaScreen that we use is as follows: We create a standard alpha buffer (50mM HEPES, 150mM NaCl, 0.1% w/v BSA, 0.01% w/v Tween20) at pH 8.0 and make up two stock solutions at 2x final concentration in the alpha buffer. Solution A contains Human His6-CBX7 is used with biotinylated-H3K27me3 (residues 20-34), at 100nM and 50nM respectively. Solution B contains 20nM streptavidin donor beads and 20nM nickel acceptor beads. For 384 well assay formats, 10uL of solution A is added to each well of the assay plate and the plate is spun at 1000 rpm for 30 seconds. 100 nL of experimental ccompounds from stock plates are delivered by robotic pin transfer using a Janus Workstation (PerkinElmer), allowing the compounds to interact with CBX7 binding prior to assay measurement, followed by another spin and an incubation room temperature. Finally, 10uL of solution B is added to each well, the plate is spun again and then incubated at room temperature. AlphaScreen measurements are performed on an Envision 2104 (PerkinElmer) utilizing the manufacturer's protocol that has the correct excitation and emission wavelengths, cutoff filters, delay time, etc. We also do a crosstalk calculation through the Envision software to correct for luminescence for adjacent wells while reading the plate. The signal is then normalized to DMSO control wells on the compound plate prior to creation of the IC50 curves.

Comment: