Pain-research peptide fragment (HRWDF / CHEMBL2372623)
A tiny lab-made peptide used as a building block in pain research, designed to engage several pain-related receptor systems at once; lab tool only, not a medicine.
A researcher, an agent, or an algorithm wrote down the sequence and picked a target to hit.
An AI model like OpenFold3 or AlphaFold built a 3D structure and scored how well it fits the binding site.
A second contributor repeated the computation on their own hardware and the scores matched.
A chemistry service or a researcher ordered the sequence, it was manufactured, and mass spectrometry confirmed the right molecule was produced.
A binding or activity measurement confirmed that it actually does what the computer predicted — or didn't.
What this is
This is a designed five-residue peptide (HRWDF) reported in the medicinal-chemistry literature as a fragment used to build trivalent ligands targeting three pain-relevant receptors at once: the opioid system, the cholecystokinin system, and the melanocortin system (Lee 2010). It is not a marketed drug, not an endogenous hormone, and not a wellness peptide — it is a research-stage chemical tool. The platform record lists it under its ChEMBL identifier (CHEMBL2372623) with a measured binding affinity of Ki = 15.0 nM, and it is associated on the platform with two primary receptor targets, CCKAR (cholecystokinin-1 receptor) and OPRD1 (the delta-opioid receptor).
The C-terminal Trp-Asp-Phe motif in HRWDF is the same Trp-Met-Asp-Phe-like pharmacophore that drives binding to the cholecystokinin-1 receptor in natural CCK peptides, which is why short sequences ending in this triad show up repeatedly in CCK-receptor medicinal chemistry.
What it does
In the assay reported by Lee and colleagues (2010), HRWDF and related short sequences were used as the cholecystokinin-binding arm of trivalent (three-receptor) ligand designs aimed at pain. The biological rationale for combining opioid, cholecystokinin, and melanocortin pharmacology in a single molecule is that all three systems converge on pain processing in the spinal cord and brain, and that simultaneous engagement of multiple receptors can in principle produce analgesia at lower per-receptor exposures than a single-receptor drug.
This card represents a chemistry building block from that program, not a finished candidate. There is no in vivo efficacy claim attached to HRWDF as a standalone peptide; the published activity is the receptor-binding measurement at CCKAR (Ki = 15.0 nM, ChEMBL CHEMBL2372623).
Evidence
- Human: No human trials.
- Animal: No standalone in vivo data attached to this 5-residue fragment in the source literature available to this card.
- In vitro: Binding affinity at the cholecystokinin-1 receptor (CCKAR) reported as Ki = 15.0 nM (ChEMBL CHEMBL2372623), in the context of trivalent opioid/CCK/melanocortin ligand design (Lee 2010).
Regulatory status
- US: Not an approved drug. No FDA pathway. This is a research-grade chemical fragment.
- EU / international: Not an approved drug in any jurisdiction known to this card.
- WADA: Not specifically named on the Prohibited List. WADA's S2 category (peptide hormones, growth factors, related substances and mimetics) is written broadly; a peptide used outside an approved indication may fall under its scope. Athletes should consult their national anti-doping organization before using any unapproved peptide.
Related peptides
- Cholecystokinin (CCK) — the endogenous gut-brain peptide hormone whose C-terminal sulfated octapeptide (Asp-Tyr(SO₃)-Met-Gly-Trp-Met-Asp-Phe-NH₂) is the natural ligand at CCKAR. The HRWDF sequence carries the Trp-Asp-Phe pharmacophore motif shared with this natural ligand family.
▸full evidence table1 metrics
| metric | value | tool |
|---|---|---|
| Ki | 15 nM | GPCRDB/ChEMBL |
▸structural qualityopenfold3
| metric | value | note |
|---|---|---|
| gpde | 1.196 | global PDE — lower = better |
| disorder | NaN | fraction disordered |
▸3-letter notation
▸recipeboltz-2 1.0
| parameter | value |
|---|---|
| model | boltz-2 1.0 |
| weights | — |
| hardware | nvidia_nim_api |
| mlx version | — |
| python | — |
| random seed | — |
| msa strategy | none |
| diffusion samples | 1 |
| runtime | — |
| predicted by | mlx@peptide |
| predicted at | 2026-04-24 |
▸citationbibtex
@peptide{pep10310,
sequence = {HRWDF},
target = {cckar},
author = {peptidemodel},
year = {2026},
status = {bioassayed}
}