## Endpoint to Predict
- Endpoint scope: assay
- Measurement type: IC50
- Label type: continuous
- Binary semantics: pchembl
- Assay description: High Throughput Syk Biochemical Assay: Syk activity was measured using KinEASE (Cisbio), a time-resolved fluorescence resonance energy transfer (TR-FRET) immunoassay. In this assay, Syk-catalyzes the phosporylation of a XL665-labeled peptide substrate. Europium conjugated phospho-tyrosine specific antibody binds the resulting phosphorylated peptide. Formation of phosphorylated peptide is quantified by TR-FRET with Europium as the donor and XL665 the acceptor in a 2-step endpoint assay. In brief, test compounds serially diluted in DMSO were delivered into Corning white, low volume, non-binding 384 well plates using the Echo 550 acoustic liquid dispenser (Labcyte®). Syk enzyme and substrates were dispensed into assay plates using a Multi-Flo (Bio-Tek Instruments). The standard 5 μL reaction mixture contained 20 μM ATP, 1 μM biotinylated peptide, 0.01 nM of Syk in reaction buffer (50 mM Hepes, pH 7, 0.02% NaN3, 0.1% BSA, 0.1 mM Orthovanadate, 5 mM MgCl2, 1 mM DTT, 0.03% NP-40). After 30 minutes of incubation at room temperature, 5 μL of Stop and Detect Solution (1:200 Europium Cryptate labeled anti-phosphorylated peptide antibody solution and 125 nM strepavidin-XL665 Tracer in a 50 mM Hepes pH 7 detection buffer containing sufficient EDTA) was added. The plate was then further incubated for 120 minutes at room temperature and read using an Envision 2103 Multilabeled reader (PerkinElmer) with excitation/emission/FRET emission at 340 nm/615 nm/665 nm, respectively. Fluorescence intensities at 615 nm and 665 nm emission wavelengths were expressed as a ratio (665 nm/615 nm). Percent inhibition was calculated as follows: 10% Inhibition=100×(RatioSample−Ratio0% Inhibition)/(Ratio100% Inhibition−Ratio0% Inhibition) where 0.1% DMSO (0% inhibition) was the negative control and 1 μM K252a (100% inhibition) was used as the positive control. Activity of the compounds of Examples 1-7 are provided in the following table, demonstrating the compounds are Syk inhibitors with IC50 below 50 nM.
- Assay organism: Homo sapiens
- Target name: Tyrosine-protein kinase SYK
- Target type: SINGLE PROTEIN
- Target organism: Homo sapiens

## Reference Molecule A
- Canonical SMILES: Nc1cncc(-c2cn3ccnc3c(Nc3ccc(N4CCO[C@@H](CO)C4)cc3)n2)n1
- Properties:
- ChEMBL ID: CHEMBL3953841
- Molecule type: Small molecule
- Molecular weight: 418.46
- Heavy atoms: 31
- Hydrogen bond donors: 3
- Hydrogen bond acceptors: 9
- TPSA: 126.72
- LogP: 1.71
- Rotatable bonds: 5
- Ring count: 5
- Aromatic rings: 4
- Formal charge: 0
- Fraction Csp3: 0.24
- QED: 0.44

## Known Reference Result on This Endpoint
- Molecule A clean result: median pChEMBL = 7.88
- This result is provided as context for predicting Molecule B on the same endpoint.

## Reference Molecule A Other ChEMBL Evidence
- type IC50; relation =; value 13.3; units nM; pChEMBL 7.88; comment 808273

## Query Molecule B
- Canonical SMILES: Nc1cncc(-c2cn3ccnc3c(Nc3ccc(N4CCN(CC(CO)CO)CC4)cc3)n2)n1
- Properties:
- ChEMBL ID: CHEMBL3973635
- Molecule type: Small molecule
- Molecular weight: 475.56
- Heavy atoms: 35
- Hydrogen bond donors: 4
- Hydrogen bond acceptors: 10
- TPSA: 140.96
- LogP: 1.23
- Rotatable bonds: 8
- Ring count: 5
- Aromatic rings: 4
- Formal charge: 0
- Fraction Csp3: 0.33
- QED: 0.29

## Molecule Similarity
- Weighted Tanimoto: 0.67

Answer: 7.84