[Trp3,Arg5]-Ghrelin (1-5), also represented as GSWFR, is a five-residue synthetic ghrelin analog designed to retain growth hormone secretagogue receptor activity within a minimal peptide scaffold.

The sequence replaces the lipid-modified Ser3 of native ghrelin with tryptophan and introduces Arg at position 5, producing a compact all-L-amino-acid ligand for studies of GHS receptor recognition and ghrelin structure–activity relationships.

Product Information

A Five-Residue Ghrelin-Derived Ligand

Native ghrelin is a 28-residue peptide whose Ser3 normally carries an n-octanoyl chain. GSWFR replaces that lipid-modified residue with the bulky aromatic side chain of tryptophan.

This design demonstrates that some of the hydrophobic recognition normally supplied by Ser3 acylation can be reproduced through amino-acid side-chain chemistry in a much shorter ligand.

Minimal Sequence and GHS Receptor Affinity

The original pharmacological characterization reported measurable affinity of GSWFR for the growth hormone secretagogue receptor, with an IC₅₀ of approximately 10 µM under the reported binding conditions.

The peptide also stimulated growth hormone secretion in experimental animals. These findings established the N-terminal region of ghrelin as a compact source of information for designing small peptide GHSR ligands.

We recommend treating the reported affinity as study-specific rather than a universal potency specification because receptor expression, assay format and competing ligand conditions can change apparent binding values.

Trp3 Versus Ser3 Octanoylation

This comparison makes GSWFR particularly useful for examining which chemical features are sufficient for receptor recognition without reproducing the entire endogenous hormone.

Feeding and Neuroendocrine Research

In the original mouse studies, centrally administered GSWFR increased food intake. The response was reduced by a GHS receptor antagonist, supporting GHSR involvement, and was also sensitive to blockade of neuropeptide Y Y1 signaling.

These observations connect the minimal ligand not only to receptor binding but also to downstream neuroendocrine circuitry under the specific experimental conditions tested.

Peptide Design and SAR Applications

Because GSWFR contains only five conventional L-amino acids and does not require fatty-acid conjugation, it provides a practical starting scaffold for systematic substitutions, truncation analysis and receptor-directed peptide optimization.

Researchers developing sequence variants can use our Synthetic Peptide Library capabilities for alanine scanning, positional substitution or small focused libraries.

Individual analogs can also be evaluated through Chemical Peptide Synthesis.

Frequently Asked Questions

Does [Trp3,Arg5]-Ghrelin (1-5) contain an octanoyl group?

No. Position 3 is tryptophan rather than octanoylated serine.

What is the sequence of this peptide?

The sequence is Gly-Ser-Trp-Phe-Arg, abbreviated GSWFR.

Why is this peptide useful for ghrelin SAR?

It reduces the 28-residue endogenous ligand to a five-residue scaffold while retaining measurable GHS receptor affinity and experimentally demonstrated agonist activity.

Is its potency equivalent to full-length ghrelin?

No. It is best treated as a minimal ghrelin-derived research agonist rather than a potency-equivalent substitute for native acyl ghrelin.

Research Use Only.