## Endpoint to Predict
- Endpoint scope: assay
- Measurement type: Ki
- Label type: continuous
- Binary semantics: pchembl
- Assay description: Competitive Inhibition Assay Using [I125]-NDP-a-MSH: A competitive inhibition binding assay is performed using membrane homogenates prepared from HEK-293 cells that express recombinant hMC4-R, hMC3-R, or hMC5-R, and from B-16 mouse melanoma cells (containing endogenous MC1-R). In some instances, HEK-293 cells that express recombinant hMC1-R were employed. In the examples that follow, all MC3-R, MC4-R and MC5-R values are for human recombinant receptors. MC1-R values are for B-16 mouse melanoma cells, unless the heading is hMC1-R, in which case the value is for human recombinant MC1-R. Assays were performed in 96 well GF/B Millipore multiscreen filtration plates (MAFB NOB10) pre-coated with 0.5% bovine serum albumin (Fraction V). Membrane homogenates were incubated with 0.2 nM (for hMC4-R) 0.4 nM (for MC3-R and MC5-R) or 0.1 nM (for mouse B16 MC1-R or hMC1-R) [I125]-NDP-α-MSH (Perkin Elmer) and increasing concentrations of test peptides of the present invention in buffer containing 25 mM HEPES buffer (pH 7.5) with 100 mM NaCl, 2 mM CaCl2, 2 mM MgCl2, 0.3 mM 1,10-phenanthroline, and 0.2% bovine serum albumin. After incubation for 60 minutes at 37° C., the assay mixture was filtered and the membranes washed three times with ice-cold buffer. Filters were dried and counted in a gamma counter for bound radioactivity. Non-specific binding was measured by inhibition of binding of [I125]-NDP-α-MSH in the presence of 1 uM NDP-α-MSH. Maximal specific binding (100%) was defined as the difference in radioactivity (cpm) bound to cell membranes in the absence and presence of 1 uM NDP-α-MSH. Radioactivity (cpm) obtained in the presence of test compounds was normalized with respect to 100% specific binding to determine the percent inhibition of [I125]-NDP-α-MSH binding. Each assay was conducted in triplicate and the actual mean values are described, with results less than 0% reported as 0%. Ki values for test peptides of the present invention were determined using Graph-Pad Prism curve-fitting software.
- Assay cell type: HEK293
- Target name: Melanocortin receptor 4
- Target type: SINGLE PROTEIN
- Target organism: Homo sapiens

## Reference Molecule A
- Canonical SMILES: CC(=O)N[C@@H](CCCNC(=N)N)C(=O)N[C@H]1CC(=O)NCCCC[C@@H](C(N)=O)NC(=O)[C@H](Cc2c[nH]c3ccccc23)NC(=O)[C@H](CCCNC(=N)N)NC(=O)[C@@H](Cc2ccccc2)NC(=O)[C@H](Cc2ccc(C(N)=O)cc2)NC1=O
- Properties:
- ChEMBL ID: CHEMBL3644307
- Molecule type: Small molecule
- Molecular weight: 1120.29
- Heavy atoms: 81
- Hydrogen bond donors: 17
- Hydrogen bond acceptors: 12
- TPSA: 458.57
- LogP: -2.59
- Rotatable bonds: 19
- Ring count: 5
- Aromatic rings: 4
- Formal charge: 0
- Fraction Csp3: 0.41
- QED: 0.03

## Known Reference Result on This Endpoint
- Molecule A clean result: median pChEMBL = 7.52
- This result is provided as context for predicting Molecule B on the same endpoint.

## Reference Molecule A Other ChEMBL Evidence
- type Ki; relation =; value 30; units nM; pChEMBL 7.52; comment 441142

## Query Molecule B
- Canonical SMILES: CC(=O)N[C@@H](CCCNC(=N)N)C(=O)N[C@H]1CCNC(=O)CCC[C@@H](C(N)=O)NC(=O)[C@H](Cc2c[nH]c3ccccc23)NC(=O)[C@H](CCCNC(=N)N)NC(=O)[C@@H](Cc2ccccc2)NC(=O)[C@H](CCN)NC1=O
- Properties:
- ChEMBL ID: CHEMBL3646859
- Molecule type: Protein
- Molecular weight: 1030.21
- Heavy atoms: 74
- Hydrogen bond donors: 17
- Hydrogen bond acceptors: 12
- TPSA: 441.5
- LogP: -3.58
- Rotatable bonds: 18
- Ring count: 4
- Aromatic rings: 3
- Formal charge: 0
- Fraction Csp3: 0.48
- QED: 0.03

## Molecule Similarity
- Weighted Tanimoto: 0.78

Answer: 7.46