## Endpoint to Predict
- Endpoint scope: assay
- Measurement type: IC50
- Label type: continuous
- Binary semantics: pchembl
- Assay description: Enzymatic Assay: Enzyme activities were determined kinetically in a final volume of 200 μl for 10 minutes at 37° C. by measuring the initial velocities of pNA release (405 nm) from the substrate using a Spectramax plus microtiterplate reader (Molecular devices). One unit of enzyme activity was defined as the amount of enzyme that catalyzes the release of 1 μmol pNA from the substrate per minute under assay conditions. The chromogenic substrate Gly-Pro-p-nitroanilide (100 μmol/l) was used at pH 8.3 for DPP IV, Lys-Ala-p-nitroanilide (1 mmol/l) at pH 5.5 for DPP II, Ala-Pro-p-nitroanilide (300 μmol/l) at pH 7.4 for DPP9 and Ala-Pro-p-nitroanilide (2 mmol/l) at pH 7.4 for FAP activity measurement. To evaluate the endopeptidase activity of FAP and the influence of inhibitors thereon, Z-Gly-Pro-AMC and Z-Gly-Pro-p-nitroanilide were used at a final concentration of 300 and 100 μmol/l, respectively. The substrate concentrations were chosen around the Km value obtained under the assay conditions used. Buffer compositions for the DPP assays were reported before in the purification articles−vide supra. The FAP assay buffer consisted of 50 mM Tris pH7.4 containing 100 mmol/l NaCl and 0.1 mg/ml bovine serum albumin. The PREP activity was measured as described by Brandt et al. using the chromogenic substrate Z-Gly-Pro-p-nitroanilide (0.25 mmol/l) at pH 7.5 in the presence of 10 mmol/l DTT. Test compounds were dissolved and diluted in DMSO (final concentration DMSO during assay 5% v/v) except for FAP where dilution of the inhibitor was done in water. Inhibitors are pre-incubated with the enzyme for 15 min at 37° C. before starting the assay by the addition of substrate. The concentration of enzyme and of inhibitor during the preincubation is double of the final concentration during activity measurement.
- Target name: Prolyl endopeptidase
- Target type: SINGLE PROTEIN
- Target organism: Homo sapiens

## Reference Molecule A
- Canonical SMILES: N#C[C@@H]1CCCN1C(=O)CNC(=O)c1ccnc2cc(Cl)ccc12
- Properties:
- ChEMBL ID: CHEMBL2385272
- Molecule type: Small molecule
- Molecular weight: 342.79
- Heavy atoms: 24
- Hydrogen bond donors: 1
- Hydrogen bond acceptors: 4
- TPSA: 86.09
- LogP: 2.13
- Rotatable bonds: 3
- Ring count: 3
- Aromatic rings: 2
- Formal charge: 0
- Fraction Csp3: 0.29
- QED: 0.93

## Known Reference Result on This Endpoint
- Molecule A clean result: median pChEMBL = 5.85
- This result is provided as context for predicting Molecule B on the same endpoint.

## Reference Molecule A Other ChEMBL Evidence
- type IC50; relation =; value 1400; units nM; pChEMBL 5.85; comment 407121

## Query Molecule B
- Canonical SMILES: N#C[C@@H]1CCCN1C(=O)CNC(=O)c1ccncc1
- Properties:
- ChEMBL ID: CHEMBL3233554
- Molecule type: Small molecule
- Molecular weight: 258.28
- Heavy atoms: 19
- Hydrogen bond donors: 1
- Hydrogen bond acceptors: 4
- TPSA: 86.09
- LogP: 0.33
- Rotatable bonds: 3
- Ring count: 2
- Aromatic rings: 1
- Formal charge: 0
- Fraction Csp3: 0.38
- QED: 0.85

## Molecule Similarity
- Weighted Tanimoto: 0.6

Answer: 4.95