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: TargetID_659_CEMA

Protocol: Black, standard capacity streptavidin-coated 384-well plates (Pierce 15407) were first washed with 50 L of phosphate buffer (100 mM, pH 7.0; PB7) three times using a Biotek 405 ELX plate washer. Subsequently, 5 L of biotinylated pre-miRNA substrate (500 nM final) was dispensed into the plate using a Multidrop Combi Reagent Dispenser (Thermo Scientific). Plates were then centrifuged for 1 min at 1,000 RPM (223 g), sealed with plate tape, and incubated overnight at 4 C. The following morning, plates were washed three times with 50 L of PB7, followed by the addition of 5 L of Dicer digest buffer (20 mM Tris, 12 mM NaCl, 2.5 mM MgCl2, 1 mM fresh DTT, and 4.5% DMSO) and centrifugation. Compounds (50 nL of 5 mM DMSO stock, 25 M final) were then added into the sample wells using a Sciclone (Caliper) liquid handler with V&P pintool; the same volume of DMSO was added to the control wells. The plates were incubated at 25 C for 15 min before addition of 5 L of digest buffer containing 217 g/nL Dicer (108 g/mL Dicer, 5% glycerol and 0.01% Triton X-100 final, excess with respect to pre-miRNA). For the positive control wells, digest buffer without Dicer was added. The plates were centrifuged again and resealed before being placed in a 37 C incubator for 5 h. After Dicer cleavage, plates were washed three times with 50 L of PB7. mTet-HRP in PB7 (10 L, 750 nM final) was then dispensed into each well. The plates were subsequently centrifuged, sealed, and incubated at 25 C for 2 h. Plates were then washed three times with 50 L of wash buffer (2 mM imidazole, 260 mM NaCl, 0.5 mM EDTA, 0.1% Tween-20, pH 7.0), followed by washing three additional times with 50 L of PB7. Finally, SuperSignal West Pico (25 L; Pierce) was added, the plates were incubated at 25 C for 5 min, and chemiluminescence signal was detected using a PHERAstar plate reader using LUM plus module (BMG Labtech).

Comment: The activity outcome is based on a Z-score (number of standard deviations from the negative control mean) of 3 or higher on at least 50% times that the sample was screened.

For instance, if the sample was screened in n=4 runs, it would be considered active only if it had a Z-score of 3 or above in at least 2 runs.

External ID: HMS791

Protocol: Prior to screening, FITC LANA1-23 was stored lyophilized at -80 degC and freshly purified chicken nucleosomes were stored at 4 degC in 20 mM Tris pH 7.5, 600 mM NaCl, 0.2 mM EDTA, 0.5 mM B-Mercaptoethanol.

On the day of screening, FITC LANA1-23 was resuspended at 50 uM in TEN-BT buffer (10 mM Tris-HCl (pH 7.5), 1 mM EDTA (pH 8.0), 2.5 mM NaCl, 5 mM Beta-mercaptoethanol, 0.01% Triton-X-100) and diluted to a final concentration of 50 nM in TEN-BT buffer plus 240 nM of purified nucleosomes (480 nM LANA peptide binding sites). 30 uL per well were dispensed in column 1-22 in Corning #3575 black 384 well plates.

Wells in column 23 contained 30 uL of the same mixture (for pilot screen) or with the addition of 10 uM monensin (for HTS) as a negative control. In column 24, 1250 nM unlabeled WT LANA1-23 peptide (for pilot screen) or 10 uM mitoxantrone (for HTS) was added to the wells as a positive control. Compounds were transferred into wells via stainless steel pin array (100 nL) and the reaction was incubated at room temperature for 10 to 45 minutes (stable for up to 2 hours). Library plates were screened in duplicate, with both assay plates in a given set prepared on the same day.

Following a room temperature incubation of 10 to 45 minutes, the assay is read on a EnVision plate reader using a 480 nM excitation filter, 535 nM S and P emission filters and D505fp/D535 dichoric mirror. mP value for FP measurement = 1000*(S-G*P)/(S+G*P) where S= , P=, G= G-factor. The G Factor = 1.

Comment: LANA 1-23 peptide containing the first 23 amino acids of the LANA protein from Kaposi's sarcoma herpesvirus (KSHV) was synthesized with an N-terminal FITC via a beta alanine linker and HPLC purified (peptide sequence: [FITC]-Beta alanine-MAPPGMRLRSGRSTGAPLTRGSC-[NH2]).

Data analysis: Z-scores were calculated for each replicate well using the mean and standard deviation of plate experimental well FP values. Compounds were considered active if the Z-score for both replicates < -2. Wells with high total fluorescence intensity (high S and P channel values) were excluded from further consideration. Activity scores were calculated based on replicate average FP Z-scores. For wells with average Z-score >= 0, the activity score was set to 0. For wells with replicate average Z-score < 0, replicate Z-score was divided by 4 and multiplied by -100. The replicate average was then used to determine the well activity score. Values > 100 (replicate average Z-score < -4) were set to 100.

External ID: MScreen:TargetID_600

Protocol: C-terminally 6xHis tagged CDK2/Cyclin A complex and N-terminally Flag tagged CDC25B C473S (372-566) were expressed and purified. Proteins were incubated together at a final concentration of 125 nM each for 1 hr prior to incubation with compound for 1 hr, followed by addition of anti-6xHis europium cryptate donor beads (Cisbio) and anti-Flag XL-665 acceptor beads (Cisbio) at a final dilution of 1:350 for 1 hr. 20mM potassium fluoride was added 10 minute prior to plate reading. Assay reagents were dispensed using a multidrop liquid dispenser (Thermo Scientific) onto uncoated, black, low-volume, 384-well plates (Corning). Assay plates were quantified using an Envision plate reader (Perkin-Elmer) with excitation of the europium crytate donor at 337 nm wavelength and emission of the donor at 620 nm and emission of the XL-665 acceptor at 665 nm in 18 uL volumes. Assays were performed in a buffer containing 50 mM Tris (pH 7.5), 50 mM NaCl, 10mM MgCl2, 1mM TCEP, with addition of and 1mM ATP, 0.05% BSA, and 0.05% Tween-20 immediately prior to the start of the assay.

Comment: The activity outcome is based on a Z-score (number of standard deviations from the negative control mean) of 3 or higher on at least 50% times that the sample was screened.
For instance, if the sample was screened in n=4 runs, it would be considered active only if it had a Z-score of 3 or above in at least 2 runs.

This screen was funded by NIH grant number: R01CA181185

External ID: HMS1303

Protocol: Prior to screening, lyophilized FITC-GIV peptide (a.a. 1671-1701) is dissolved in 100% DMSO to a concentration of 0.5 mM, then further diluted with water to a final concentration of 50 microM. One stock was prepared in batch for the entire screen and aliquoted. All protein stocks were stored at -80C. Thawing of aliquots on the day of the assay was performed rapidly at room temperature.

Prior to transfer of screening compounds, experimental wells of 384-well assay plates were pre-filled with 37.8 nM of FITC-GIV peptide (for 25 nM final concentration) in a 10 microL volume of assay buffer (50 mM Tris [pH 7.4], 100 mM NaCl, 10 mM MgCl2, 5 mM EDTA, 0.4% NP-40, 30 microM GDP, 1 mM DTT). Control wells were pre-filled with 37.8 nM of FITC-GIV peptide in 10 microL of assay buffer containing either 1% DMSO (vehicle negative control) or 45.3 microM AlCl3+15.1 mM NaF (AlF4- positive control). Each plate contained 16 negative control and 16 positive control wells. Plates were centrifuged at 1000xg for 2 minutes to eliminate bubbling on the surface. Following, 100 nL of experimental compound was pin-transferred into individual wells for each of two replicate assay plates (A&B). After pin-transfer, 5 microL of 3 microM His-tagged rat Galphai3 purified from E. coli (for 1 microM final concentration) was added to each well, and assay plates were shaken at low speed for 5 seconds. Final assay volume was 15 microL. Plates were centrifuged at 1000xg for 2 minutes to eliminate bubbling on the surface and shaken for 10 seconds prior to an incubation of 90 minutes at room temperature. Plates were protected from prolonged light exposure. All manipulations were performed at room temperature.

Assay plates were read with a PerkinElmer Wallac EnVision Multilabel 2103 plate reader using the fluorescent polarization measurement technology with a D505fp/D535 dual mirror and a 480 nm excitation filter. 535 nm emission filters were used for P and S channel reads at 11 mm measurement height with 30 flashes and detector gains of 319 and 563. G-factor 0.96.

Negative control: DMSO
Positive control: Aluminum tetrafluoride (AlF4-, composite of NaF and AlCl3)

Comment: Calculated result values and scoring of active compounds:

Z-score: Indicates the number of standard deviations an experimental condition is from the mean. It is calculated based on plate average (u) and standard deviation (s) of experimental well fluorescence polarization (FP) measurements for each replicate. Z-score (z) is defined as the quotient of the mean of the experimental well population subtracted from an individual well's FP (x), divided by the standard deviation within the experimental wells; z = (x-u)/s.

Normalized percent control: calculated by subtracting plate average positive control FP from experimental well FP, dividing by the difference between plate average negative and positive control FP, and multiplying by 100.

STD: the number of standard deviations from the plate average negative control FP for each replicate experimental well

Compound wells with FP values exceeding +5 standard deviations from the negative control sample average were flagged as potential aggregators or fluorescence quenchers due to their high polarization signal (HighPol) and were excluded from further consideration. Activity scores were calculated by averaging the replicate normalized percent of control values and subtracting from 100 (score based on single replicate if data for other replicate was excluded for any reason). Result values < 0 were set to 0 (no activity) and > 100 were set to 100 (100% activity). Compounds with activity score >= 15 were considered active.

External ID: CF Folding

Protocol: A high throughput 384-well microplate based fluorescence assay was developed using HeLa cells engineered to express F508del-CFTR. Cells were maintained in cell culture media (High Glucose DMEM (Gibco) supplemented w/ 10% FBS (Gibco)). For the assay, cells were trypsinized (0.25% Trypsin-EDTA solution (Gibco)) and resuspended in assay media (cell culture media + 1% Pen/Strep (Gibco)) at a density of 320,000 cells per ml. Cells were dispensed to the assay plates (Corning 3712) in 25 ul using a Wellmate (Matrix/Thermo). Plates were incubated overnight at 37C, 5% CO2 and high humidity. The next day, compounds were prepared by making a dilution in assay media to a concentration of either 150 uM or 60 ug/ml (6x) depending on the library being screened. Then 5 ul of the diluted compound was transferred to the assay plate containing the cells. Assay plates were incubated for 24 hours 37C, 5% CO2 and high humidity. Following incubation with the compounds, relative cell number was determined by adding 3 ul of alamarBlue (TREK Diagnostics) and incubating the plates at 37C, 5% CO2 and high humidity, until cell control values reached ~4 million, as measured with a fluorescent intensity protocol on an Envision multimode plate reader (Perkin Elmer) (excitation 535 nm, emission 595 nm wavelengths) . Following the alamarBlue read, the media was removed and the cells were fixed with the addition of 13 ul of 4% paraformaldehyde in PBS (pH 7.4) and incubated for 10 minutes at room temperature. Plates were washed twice with PBS to remove the fixative. Cells were permeabilized with the addition of blocking solution (PBS, 0. 1% Triton X-100, 10 mg/ml BSA) and incubated at room temperature for 30 minutes. The blocking solution was removed and the primary antibody mixture was added in 13ul (Antibodies UNC570 and UNC596; CFF Therapeutics, Inc., Bedford, MA) at a 1/5000 dilution of each antibody in blocking solution. Plates were then incubated over night at 4oC. Primary antibody was removed by washing three times with 50 ul of wash solution (PBS, 0.1% Triton X-100) with at least 5 minutes between wash cycles. Secondary antibody (Alexa 488 anti-mouse IgG Invitrogen) was then added in a volume of 13 ul (1/1000 dilution in blocking solution) and incubated for two hours at room temperature in the dark. To remove excess secondary antibody, plates were washed three times with 50 ul of wash solution and one time with 50 ul of PBS. Plates were read from the bottom using a fluorescent intensity protocol on an Envision multimode plate reader (485 nm excitation and 535 nm emission).
To minimize the disruption of the cell monolayer during the numerous washes, the following process was used. The removal of media or other reagents for the wells of the microtiter plate was done using a Biomek FX (Beckman, Fullerton CA) with a 384 tip multichannel head. Aspiration was done at a slow rate following the liquid level with the tip positioned in the top right corner of the well. All solution additions, starting with the fixative, were done with a Matrix Wellmate. Again to avoid disturbing the cell monolayer, the plate offset was adjusted so that the liquid dispensed to the left wall of the well rather than directly on the cell monolayer.
For the screen, approximately ten thousand compounds from a mix of FDA and diverse libraries (MicroSource Pharmacon-1600 (FDA), Enzo (FDA), Selleck (FDA) and Enamine) were tested at a final concentration 25 uM (Enzo, Selleck & MS Pharmakon) or 10 ug/ml (Enamine 30K diversity set). The proteasome inhibitor ALLN was used as the positive control (50 uM) and 100 uM Hyamine was used as a viability control on all microtiter plates. All wells including the cell controls contained 0.5% DMSO. In-plate controls were used to normalize the data and results were reported as fold increase above the cell control and normalized to relative cell number derived from the alamarBlue data.
Ninety six compounds identified in the single dose screen were evaluated further in dose response. Compound high dose was twice the screening concentration and a ten point series of two fold dilutions were done for each compound. DMSO concentration was 1% for in all wells. Compounds were evaluated in both the immunostain assay and in the cell viability assay.

Data Analysis: Thirty two control wells containing cells only, 24 wells containing Hyamine and 8 wells containing ALLN were included on each assay plate and used to calculate Z' value for each plate and to normalize the data on a per plate basis. Data were analyzed using the IDBS Activity Base software. Results were expressed as Fold Increase (FI) for the immunostain assay and cell viability (V) for the alamarBlue assay. Final data was reported as Normalized fold increase (NFI). Data was analyzed as follows FI=DataValue/Median cell control, V= (DataValue-median Hyamine control)/(median cell control -median Hyamine control) and NFI=FI/V.

For the immunostain dose response assay, IC50 values were calculated for active compounds by plotting the FI for each concentration, and using a 4 parameter Levenburg-Marquardt algorithm with the minimum limit set at 0. Similarly, EC50 values were calculated for the cell viability dose response assay, plotting the % Viability at each concentration and also using a 4 parameter Levenburg-Marquardt algorithm with the minimum limit set at 0 and the maximum limit set at 100.

Outcome- From the primary screen, compounds selected as Active were those that met one of the following two criteria: (1) Fold Induction >/= 1.5, Cell Viability >/= 50% and the ratio of Fold Induction to Cell Viability >/= 1.5; or (2) Fold Induction >/= 1, Cell Viability >/= 50% and the ratio of Fold Induction to Cell Viability >/=1.75. While 101 compounds met this criteria, 96 were ultimately selected for confirmatory screening. For the dose response screen, compounds were labeled as "Active" if they showed at least 8 fold increase over the ALLN control at any concentration.

Comment: Possible Artifacts: Possible artifacts in this assay include, but are not limited to, compounds that are fluorescent, absorb at the excitation or emission wavelengths, or non-specifically upregulate protein expression

External ID: GPR151_PHUNTER_AG_LUMI_1536_1X%ACT

Protocol: Assay Overview:
TThe goal of this NIH sponsored research project was to identify GPR151 agonists via high-throughput screening (HTS) efforts. In brief, the McDonald Lab transferred the GPR151 AG 384wpf assay to Scripps for implementation and miniaturization to 1,536-well format followed by screening against the Scripps Drug Discovery Library (SDDL). A counterscreen assay, employing GPR119 cells, was also implemented by Scripps to identify compounds that non-specifically affect the PathHunter detection method. This project was aided by cheminformatic efforts to help identify compounds that demonstrated authentic agonist pharmacology and non-promiscuous activity profiles across other primary screens run against the SDDL. At completion of the project, several compounds demonstrated activity in the GPR151 AG PathHunter assay. All compounds selected for titration were also subjected to LC-MS analysis to confirm mass and sample purity

Protocol Summary:
Prior to the start of the assay, cells were resuspended in growth media at 2000cells/well in 1536 well plates. This was followed by an incubation of 18 hours at 37C+5%CO2. Then 1uL of Opti-Mem added to all wells except high controls to which 3X EA reagentwas added to each of those wells (0.2X final in lysis buffer). Compounds were pinned at 11.20uM final concentration in 1.0% DMSO followed by a 90 minute incubation at 37C+5%CO2. At this stage 3uL of Promega Beta-Glo detection Buffer was added to all wells followed by a 1 hour incubation at room temperature. Finally the assay end point read was taken using the ViewLux imaging reader from PerkinElemer Lifesciences with a 5 second exposure. Raw assay data was imported into Scripps# corporate database and ascetrained for Z' greater than 0.5 in order to be processed futher.

The percent activation for each compound was calculated as follows:

Percent Response of compound= 100 * ((Test Well-Median Data Wells)/(Median High Control # Median Data Wells))
Where:
Test_Well is defined as wells containing GPR151 cells in the presence of test compound
High_Control represents wells containing GPR151 cells stimulated with 0.2X EA reagent
Low_Control is defined as wells containing GPR151 cells and DMSO
PubChem Activity Outcome and Score:
Standard Cutoff
The reported PubChem Activity Score has been normalized to 100% observed primary inhibition. Negative % inhibition values are reported as activity score zero.
The activity score range for active compounds is 100-1, for inactive 1-0.
List of Reagents:
GPR151 cells (supplied by Patricia McDonald)
Pen Strep (Invtirogen 15140)
FBS (Invtirogen 16140)
Hygromycin (Invtirogen 10687010)
Lysis buffer (CisBio 62CL2FDF)
EA Reagent (DiscoverX 30-411)
G418 (Gemini Bio 400-113)
Opti-MEM (Invtirogen 31985)
Trypsin (Invtirogen 15400054)
Beta Glo (Promega E4780)
1536-well plates (Greiner Bio-One, part 789173)

Comment: Due to the size of the Scripps Molecular Screening Center compound library, this assay have been run as multiple separate campaigns, each campaign testing a unique set of compounds. All data reported were normalized on a per-plate basis. Possible artifacts of this assay can include, but are not limited to: dust or lint located in or on wells of the microtiter plate, compounds that modulate well fluorescence. All test compound concentrations reported above and below are nominal; the specific test concentration(s) for a particular compound may vary based upon the actual sample provided by the Scripps Molecular Screening Center.

A mathematical algorithm was used to determine what we call the standard hit cut-off to identify active compounds. Two values were calculated: (1) the average percent activation of all compounds tested in the screen, and (2) three times their standard deviation. The sum of these two values was used as a cutoff parameter, i.e. any compound that exhibited greater percent activation than the cutoff parameter was declared active. Using this "Standard Cutoff" (= 4.91%) the primary assay yielded 6,756 active compounds ("hits")."

External ID: FBW7_ACT_ALPHA_1536_1X%ACT PRUN

Protocol: Assay Overview:
FBW7 assay principle. In this assay, either mutant or wild type (w.t.) FBW7 interact with phosphorylated cyclin E peptide (cycE~P), which will bring donor and acceptor beads into close proximity. Laser excitation of the donor beads converts oxygen to an excited singlet state. Reaction of the singlet oxygen with the acceptor beads further activates a chemiluminescence/fluorescence reaction within the same bead resulting in emitted light at 520-620 nm. Small molecule activators that enhance the mutant FBW7 interaction with the cycE~P decrease the distance of the acceptor beads, thus leading to increased signal being emitted signal.
Protocol Summary:
There are six steps in this 1536 well assay format which are listed in order. First, 2.5uL/well of a 2X working solution containing RLFbw7 [12.5nM final], Cyclin E peptide [12.5nM final], and Ni beads [5ug/mL final], in assay buffer (25mM Tris-HCl pH 7.4 + 100mM NaCl, 0.1% Tween-20, 5mM ?-Mercaptoethanol and 0.05% BSA) was dispensed into columns 1-44. Then 2.5uL/well of a 2X working solution containing WTFbw7 [12.5nM final], Cyclin E peptide [12.5nM final], and Ni beads [5ug/mL final], in assay buffer was dispensed into columns 45-48. Using the pintool transfer device 134nL of compound or control was added to each well. This achieved a nominal screening concentration of 26.1uM and 2.6% DMSO concentration. This was followed by the addition of SA beads to all wells at 5ug/mL final concentration in assay buffer. The assay was then incubated for 20 hours in a temperature controlled 25C environment followed by Alphascreen detection using the PerkinElmer EnVision.

The percent activation for each compound was calculated as follows:

100 *( ( Test_Compound - Median_Low_Control ) / ( Median_High_Control - Median_Low_Control ) )
Where:
Test_Compound is defined as wells containing RLFbw7 (mutant), cyclin E peptide and Nickel acceptor beads in the presence of test compound
High_Control is defined as wells containing WTFbw7 (wild type), cyclin E peptide and Nickel acceptor beads
Low_Control is defined as the median of the wells containing DMSO, RLFbw7 (mutant), cyclin E peptide and Nickel acceptor beads
PubChem Activity Outcome and Score:

A mathematical algorithm was used to determine active compounds. Two values were calculated: (1) the average percent activation of all compounds tested for the screen, and (2) three times their standard deviation. The sum of these two values was used as a cutoff parameter, i.e. any compound that exhibited greater percent activation than the cutoff parameter (1.85% in the case here) was declared active.
The reported PubChem Activity Score has been normalized to 100% observed primary inhibition. Negative % inhibition values are reported as activity score zero.
The activity score range for active compounds is 100-1, for inactive 1-0.
List of Reagents:
Ni Beads- PerkinEmer Lifesciences Cat#6760619R
RLFbw7-Assay Provider
WTFbw7-Assay Provider
Cyclin E peptide-Assay Provider
5M NaCl- Sigma Cat# S6546-1L
Tween20- Fisher Cat# BP337
Tris 1M pH7.4 Research Organics Cat# 9686T
BSA-Sigma Cat#A7030
?-Mercaptoethanol-SigmaM6250
1536-well plates (Corning, part 7254)

Comment: Due to the size of the Scripps Molecular Screening Center compound library, this assay may have been run as two or more separate campaigns, each campaign testing a unique set of compounds. All data reported were normalized on a per-plate basis. Possible artifacts of this assay can include, but are not limited to: dust or lint located in or on wells of the microtiter plate, compounds that modulate well fluorescence. All test compound concentrations reported above and below are nominal; the specific test concentration(s) for a particular compound may vary based upon the actual sample provided by the Scripps Molecular Screening Center.

External ID: MITF_INH_Alpha_1536_1X%INH PRUN

Protocol: Assay Overview:

The purpose of this biochemical assay is to identify MITF dimerization inhibitors that disrupt or prevent its homodimerization. This assay is a bead-based proximity assay, which employs acceptor beads and donor beads to generate a chemiluminescence signal. In this assay, Biotin-labelled MITF and His- tagged MITF homodimerization will bring donor and acceptor beads into close proximity. Laser excitation of the donor beads converts oxygen to an excited singlet state. Reaction of the singlet oxygen with the acceptor beads further activates a chemiluminescence reaction within the same bead resulting in emitted light at 520-620 nm. As designed, small molecule inhibitors that interfere with this interaction will increase the distance of the acceptor beads, thus leading to decreased signal. Compounds were tested in singlicate at a nominal test concentration of 2.6 micromolar.

Protocol Summary:
Prior to the start of the assay, 1.25#L of assay buffer (50mM HEPEs pH7.5, 250mM Sodium chloride, 0.1% Tween, 0.1% BSA) containing 10nM His-MITF_r259stop were dispensed into columns 1 thru column 2, and 1.25#L of assay buffer containing 10nM of His MBP MITF were dispensed into columns 3 thru column 48 of 1536 microtiter plates. Next, 10nL of test compounds in DMSO, 7,8-Dihydroxycoumarin (200#M final highest concentration) in DMSO, or DMSO alone (0.15% final concentration) were added to the appropriate wells before dispensing 1.25#L of 10#g/mL Acceptor beads into column 1 to 46 and 1.25#L of assay buffer into column 47 and 48. Plates were incubated in dark for 2hrs at room temperature. Then, dispenses of 1.25#L of 10nM Biotin-MITF into all columns, and 10#g/mL Donor beads into column 1 to 46 and 1.25#L of assay buffer into column 47 to 48 followed by 3hrs incubation in dark at RT, was done. Alphascreen signal was determined using an EnVision microplate reader (PerkinElmer, Waltham, MA) at 680nm excitation and 570nm emission.

The percent inhibition for each compound was calculated as follows:

100 *( ( Median_Low Control-Test Compound) / ( Median_Low Control - Median_High Control ) )

Where:

Test_Compound is defined as wells containing His-MITF + Biotin-MITF in the presence of test compound
High_Control is defined as wells containing His-MITF_r259stop + Biotin-MITF and DMSO.
Low_Control is defined as wells containing His-MITF + Biotin-MITF and DMSO

PubChem Activity Outcome and Score:

Standard Cutoff

The reported PubChem Activity Score has been normalized to 100% observed primary inhibition. Negative % inhibition values are reported as activity score zero.

The activity score range for active compounds is 100-1, for inactive 1-0.

List of Reagents:

His-tagged MITF protein (supplied by Min Guo)
His-tagged MITF_r259stop protein (supplied by Min Guo)
Biotinylated-MITF protein (supplied by Min Guo)
7,8-Dihydroxycoumarin (Sigma, part D5564)
HEPEs (Sigma, part H3375, H3784)
Sodium chloride (Fisher, part BP358-212)
Tween-20 (Fisher, part 50146671)
DMSO (Fisher, part D159)
BSA (Fisher, part BP1600-100)
AlphaScreen Beads Kit (Perkin Elmer, part 6760619L)
1536-well plates (Greiner Bio-One, part 789175)

Comment: Due to the size of the Scripps Molecular Screening Center compound library, this assay have been run as multiple separate campaigns, each campaign testing a unique set of compounds. All data reported were normalized on a per-plate basis. Possible artifacts of this assay can include, but are not limited to: dust or lint located in or on wells of the microtiter plate, compounds that modulate well fluorescence. All test compound concentrations reported above and below are nominal; the specific test concentration(s) for a particular compound may vary based upon the actual sample provided by the Scripps Molecular Screening Center.