Frog-skin nerve peptide (Bombesin-9 fragment)
A short peptide from Papua New Guinea frog skin that switches on nerve-signaling receptors tied to gut muscle activity and pain; used only as a laboratory research tool, 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.
Snapshot
Class: Amphibian neuropeptide fragment (bombesin-family)
Evidence tier: In vitro / assay evidence
Status: Research peptide; no approved therapeutic status identified
Best-supported effect: Pharmacological activity on smooth muscle preparations in a structure-activity bioassay (in vitro / ex vivo)
Main caveat: No animal efficacy data or human evidence is identified; characterization is limited to one parallel bioassay study
What this is
[Pyr-1]-Bombesin-9 is a naturally occurring nonapeptide isolated from the skin of a Papua New Guinea frog (Rana sp.). It is a C-terminal fragment of the bombesin peptide family, sharing the conserved bombesin C-terminal sequence. The pyroglutamate modification at position 1 (pGlu) replaces the N-terminal glutamine found in some related family members. The peptide is characterized primarily through one parallel structure-activity bioassay study comparing bombesin-family peptides on smooth muscle tissue.
Evidence map
| Evidence layer | Grade | What it supports |
|---|---|---|
| Human | None identified | No human evidence identifieds available literature |
| Animal | None identified | No animal in vivo evidence identifieds available literature |
| In vitro | Weak | Activity on smooth muscle preparations in a parallel bioassay of bombesin-family peptides (Erspamer et al., 1988) |
| Computational | None identified | No computational or structural prediction data attached |
| Mechanism | Plausible | Bombesin-family peptides act at bombesin receptor subtypes; SAR context from the 1988 study supports receptor-binding rationale |
Claim check
| Claim | Verdict | Evidence layer | Confidence |
|---|---|---|---|
| Pharmacological activity on smooth muscle in vitro | Supported (in vitro) | In vitro bioassay | Low — single parallel bioassay; no independent replication identified in this card |
| Selective ligand activity at a defined bombesin receptor subtype | Weak (in vitro) | In vitro bioassay | Low — the 1988 study characterizes receptor subtypes across 27 peptides; subtype selectivity for this specific fragment not individually extracted |
| Any in vivo efficacy (animal or human) | Not established | None | Low — no animal or human evidence is identifieds available literature |
Assay conditions
This section reports conditions from the pharmacological study identified. It does not establish animal or human exposure.
| Context | System | Assay condition | Timepoint | Endpoint | Limitation |
|---|---|---|---|---|---|
| Parallel bioassay | 9 smooth muscle preparations (ex vivo organ bath panel) | Concentration range not individually extracted from source | Acute | Smooth muscle contractile response; structure-activity relationship across 27 bombesin-family peptides | Exact concentration range and preparation-specific potency values for this peptide are not individually extracted; ex vivo smooth muscle is not an in vivo model |
Mechanism
[Pyr-1]-Bombesin-9 belongs to the bombesin peptide family, members of which act as agonists at bombesin receptor subtypes (BB1/NMBR, BB2/GRPR, and BB3). The conserved C-terminal sequence –GHLM–NH₂ is the primary determinant of receptor recognition in bombesin-family peptides. The N-terminal pyroglutamate modification (pGlu) at position 1 is a structural feature studied in the context of SAR relationships across the family. Primary receptor target confidence for this specific nonapeptide fragment is inferred from family membership and the 1988 bioassay context, not from dedicated binding or selectivity studies individually extracted in this card.
Chemistry
| Field | Value |
|---|---|
| Amino-acid chain | pGlu-Gln-Trp-Ala-Val-Gly-His-Leu-Met-NH₂ |
| Short notation | pGlu-QWAVGHLM-NH₂ |
| Length | 9 amino acids |
| Topology | Linear |
| N-terminal modification | Pyroglutamate (pGlu); cyclized N-terminal glutamine residue |
| C-terminal modification | C-terminal amidation (–NH₂) |
| Source | Papua New Guinea frog (Rana sp.) skin |
| Sequence confidence | Needs review — sequence provided by single catalog source; no independent chemical verification identified in this card |
Open questions
- In vivo characterization: No animal pharmacology data are identifieds source. Whether smooth muscle bioassay activity translates to in vivo effects remains uncharacterized in the attached sources.
- Receptor subtype selectivity: The 1988 Erspamer study characterizes bombesin receptor subtypes across 27 peptides; the subtype selectivity profile of this specific C-terminal nonapeptide has not been individually extracted in this card and warrants dedicated binding studies.
- Role of pGlu modification: The functional consequence of the pyroglutamate modification at position 1 relative to unmodified Gln-1 analogs is not individually resolved in the attached source material.
- Sequence verification: The sequence is sourced from a single catalog entry; primary literature verification against the Erspamer 1988 study or original isolation reports has not been performed in this card-writing pass.
▸full evidence table2 metrics
| metric | value | tool |
|---|---|---|
| ipTM | 0.9514828324317932 | boltz-2 |
| ranking score | 0.7892721891403198 | boltz-2 |
▸structural qualityopenfold3
| metric | value | note |
|---|---|---|
| gpde | 0.978 | 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{pep10631,
sequence = {QWAVGHLM},
target = {ntsr1},
author = {peptidemodel},
year = {2026},
status = {synthesized}
}