## Endpoint to Predict
- Endpoint scope: assay
- Measurement type: IC50
- Label type: continuous
- Binary semantics: pchembl
- Assay description: PI3-Kinase HTRF Assay: A PI3-Kinase HTRF® assay kit (cat No. 33-016) purchased from Millipore Corporation is used to screen compounds provided herein. This assay uses specific, high affinity binding of the GRP1 pleckstrin homology (PH) domain to PIP3, the product of a Class 1A or 1B PI3 Kinase acting on its physiological substrate PIP2. During the detection phase of the assay, a complex is generated between the GST-tagged PH domain and biotinylated short chain PIP3. The biotinylated PIP3 and the GST-tagged PH domain recruited fluorophores (Streptavidin-Allophycocyanin and Europium-labeled anti-GST respectively) to form the fluorescence resonance energy transfer (FRET) architecture, generating a stable time-resolved FRET signal. The FRET complex is disrupted in a competitive manner by non-biotinylated PIP3, a product formed in the PI3 Kinase assay.PI3 Kinase α, γ or δ activity is assayed using the PI3 Kinase HTRF® assay kit (catalogue No. 33-016) purchased from Millipore Corporation. Purified recombinant PI3Kα (catalogue No. 14-602-K), PI3Kβ (catalogue No. 14-603-K), PI3Kγ (catalogue No. 14-558-K), and PI3Kδ (catalogue No. 14-604-K) are obtained from Millipore Corporation. Purified recombinant PI3K enzyme is used to catalyze the phosphorylation of phosphatidylinositol 4,5-bisphosphate (PIP2 at 10 μM) to phosphatidylinositol 3,4,5-trisphosphate (PIP3) in the presence of 10 μM ATP. The assay is carried out in 384-well format and detected using a Perkin Elmer EnVision Xcite Multilabel Reader. Emission ratios are converted into percent inhibitions and imported into GraphPad Prism software. The concentration necessary to achieve inhibition of enzyme activity by 50% (IC50) is calculated using concentrations ranging from 20 μM to 0.1 nM (12-point curve). IC50 values are determined using a nonlinear regression model available in GraphPad Prism 5.
- Assay organism: Homo sapiens
- Target name: Phosphatidylinositol 4,5-bisphosphate 3-kinase catalytic subunit delta isoform
- Target type: SINGLE PROTEIN
- Target organism: Homo sapiens

## Reference Molecule A
- Canonical SMILES: C[C@H](NC(=O)c1c(N)nn2ccccc12)c1cc2cccc(C#Cc3cnn(C)c3)c2c(=O)n1-c1ccccc1
- Properties:
- ChEMBL ID: CHEMBL5918021
- Molecular weight: 527.59
- Heavy atoms: 40
- Hydrogen bond donors: 2
- Hydrogen bond acceptors: 5
- TPSA: 112.24
- LogP: 3.84
- Rotatable bonds: 4
- Ring count: 6
- Aromatic rings: 6
- Formal charge: 0
- Fraction Csp3: 0.1
- QED: 0.34

## Known Reference Result on This Endpoint
- Molecule A clean result: median pChEMBL = 5.7
- This result is provided as context for predicting Molecule B on the same endpoint.

## Reference Molecule A Other ChEMBL Evidence
- type IC50; relation =; value 2000; units nM; pChEMBL 5.7; comment 1002383

## Query Molecule B
- Canonical SMILES: C[C@H](NC(=O)c1c(N)nn2ccccc12)c1cc2cccc(Cl)c2c(=O)n1-c1ccccc1
- Properties:
- ChEMBL ID: CHEMBL3917188
- Molecule type: Small molecule
- Molecular weight: 457.92
- Heavy atoms: 33
- Hydrogen bond donors: 2
- Hydrogen bond acceptors: 4
- TPSA: 94.42
- LogP: 4.37
- Rotatable bonds: 4
- Ring count: 5
- Aromatic rings: 5
- Formal charge: 0
- Fraction Csp3: 0.08
- QED: 0.42

## Molecule Similarity
- Weighted Tanimoto: 0.69

Answer: 5.7