Pentapeptide-3

What Is Pentapeptide-3?

Pentapeptide-3 is a synthetic linear peptide of five amino acids, glycine, proline, arginine, proline and alanine, with an amidated C-terminus. It is sold as an ingredient for cosmetic formulations and is identified by the name pentapeptide-3 in cosmetic ingredient nomenclature.

Peer-reviewed data on pentapeptide-3 are essentially absent. A PubMed search for this page found no studies that specifically examine this molecule as of October 2026. Statements about how it works or what it does in skin therefore rest on manufacturer materials rather than on independent published research, and they are not repeated here.

Chemical Structure and Molecular Identity

Pentapeptide-3 is glycyl-L-prolyl-L-arginyl-L-prolyl-L-alaninamide, written in three-letter code as Gly-Pro-Arg-Pro-Ala-NH2. PubChem (CID 11605666) lists the molecular formula C21H37N9O5 and a molecular weight of 495.6 g/mol.

All four chiral residues are in the L-configuration, and glycine is achiral. The N-terminus is a free amine, and the C-terminal alanine carries an amide in place of the usual carboxylic acid. The two proline residues restrict backbone flexibility, and the arginine side chain carries a guanidino group. The molecule is highly polar, with a computed XLogP of -3.4 in PubChem.

Residue composition

Key identifiers

• CAS number: 135679-88-8
• InChIKey: BYWJFRMLHFQWSR-AJNGGQMLSA-N
• Systematic name: glycyl-L-prolyl-L-arginyl-L-prolyl-L-alaninamide
• Short form: GPRPA-NH2

Pentapeptide-3 is often sold as an acetate or trifluoroacetate salt, and these salt forms have different formula weights from the free peptide listed above.

What the Published Literature Covers

No peer-reviewed studies on pentapeptide-3 itself were found in PubMed as of October 2026. There are no indexed cell, animal or human studies of this sequence to summarize.

Part of the confusion around the name comes from a similarly named but unrelated ingredient. Palmitoyl pentapeptide-3 was an earlier name for the lipopeptide Pal-KTTKS (palmitoyl-lysine-threonine-threonine-lysine-serine), which is now usually called palmitoyl pentapeptide-4. The only article returned by the PubMed search for this page concerned analogues of that KTTKS peptide, not Gly-Pro-Arg-Pro-Ala-NH2, and it was excluded.

Readers comparing sources should check the sequence rather than the name. A study or label describing a palmitoylated KTTKS peptide does not apply to pentapeptide-3.

With no published reference data, researchers typically rely on HPLC and mass spectrometry certificates of analysis to confirm pentapeptide-3 identity and purity.

Regulatory and Research Status

Pentapeptide-3 is not an FDA-approved drug. It is used as a cosmetic ingredient and has not been studied in drug-development clinical trials.

With no peer-reviewed literature, its biological activity, skin penetration and safety profile have not been independently characterized. Any future research would need to establish basic properties, such as stability in formulations and activity in standardized cell or skin models, before effects in people could be assessed.

The name itself carries little structural information. In cosmetic ingredient nomenclature, a name such as pentapeptide-3 indicates the number of residues plus an identifying number, not the sequence. This is why unrelated molecules share similar names, and why the sequence and CAS number (135679-88-8) are the reliable way to identify this compound.