## Endpoint to Predict
- Endpoint scope: assay
- Measurement type: Ki
- Label type: continuous
- Binary semantics: pchembl
- Assay description: BACE1 HTRF FRET Assay: Reagents: Na+-Acetate pH 5; 1% Brij-35; Glycerol; Dimethyl Sulfoxide (DMSO); Recombinant human soluble BACE1 catalytic domain (>95% pure); APP Swedish mutant peptide substrate (QSY7-APPswe-Eu): QSY7-EISEVNLDAEFC-Europium-amide. A homogeneous time-resolved FRET assay can be used to determine IC50 values for inhibitors of the soluble human BACE1 catalytic domain. This assay monitors the increase of 620 nm fluorescence that resulted from BACE1 cleavage of an APPswedish APPswe mutant peptide FRET substrate (QSY7-EISEVNLDAEFC-Europium-amide). This substrate contains an N-terminal QSY7 moiety that serves as a quencher of the C-terminal Europium fluorophore (620 nm Em). In the absence of enzyme activity, 620 nm fluorescence is low in the assay and increased linearly over 3 hours in the presence of uninhibited BACE1 enzyme. Inhibition of BACE1 cleavage of the QSY7-APPswe-Eu substrate by inhibitors is manifested as a suppression of 620 nm fluorescence. Varying concentrations of inhibitors at 3× the final desired concentration in a volume of 10 ul are preincubated with purified human BACE1 catalytic domain (3 nM in 10 μl) for 30 minutes at 30° C. in reaction buffer containing 20 mM Na-Acetate pH 5, 10% glycerol, 0.1% Brij-35 and 7.5% DSMO. Reactions are initiated by addition of 10 μl of 600 nM QSY7-APPswe-Eu substrate (200 nM final) to give a final reaction volume of 30 μl in a 384 well Nunc HTRF plate. The reactions are incubated at 30° C. for 1.5 hours. The 620 nm fluorescence is then read on a Rubystar HTRF plate reader (BMG Labtechnologies) using a 50 millisecond delay followed by a 400 millisecond acquisition time window. Inhibitor IC50 values are derived from non-linear regression analysis of concentration response curves. Ki values are then calculated from IC50 values using the Cheng-Prusoff equation using a previously determined m value of 8 μM for the QSY7-APPswe-Eu substrate at BACE1.
- Assay organism: Homo sapiens
- Target name: Beta-secretase 1
- Target type: SINGLE PROTEIN
- Target organism: Homo sapiens

## Reference Molecule A
- Canonical SMILES: CN1C(=N)N[C@@]2(c3cc(OCC45CC(C#N)(C4)C5)ccc3F)CO[C@@H](C3CC3)C[C@H]2C1=O
- Properties:
- ChEMBL ID: CHEMBL5962358
- Molecular weight: 438.5
- Heavy atoms: 32
- Hydrogen bond donors: 2
- Hydrogen bond acceptors: 5
- TPSA: 98.44
- LogP: 2.91
- Rotatable bonds: 5
- Ring count: 7
- Aromatic rings: 1
- Formal charge: 0
- Fraction Csp3: 0.62
- QED: 0.74

## Known Reference Result on This Endpoint
- Molecule A clean result: median pChEMBL = 8.05
- This result is provided as context for predicting Molecule B on the same endpoint.

## Reference Molecule A Other ChEMBL Evidence
- type Ki; relation =; value 9; units nM; pChEMBL 8.05; comment 486271

## Query Molecule B
- Canonical SMILES: CCCOc1ccc(F)c([C@]23CO[C@@H](C4CC4)C[C@H]2C(=O)N(C)C(=N)N3)c1
- Properties:
- ChEMBL ID: CHEMBL5836908
- Molecular weight: 375.44
- Heavy atoms: 27
- Hydrogen bond donors: 2
- Hydrogen bond acceptors: 4
- TPSA: 74.65
- LogP: 2.62
- Rotatable bonds: 5
- Ring count: 4
- Aromatic rings: 1
- Formal charge: 0
- Fraction Csp3: 0.6
- QED: 0.83

## Molecule Similarity
- Weighted Tanimoto: 0.76

Answer: 7.18