Compound monograph
KTTKS (Pentapeptide-4)
KTTKS is the unmodified pentapeptide from type I procollagen that forms the peptide backbone of the palmitoylated cosmetic ingredient Matrixyl.
01
Identity & nomenclature
KTTKS is the unmodified pentapeptide from type I procollagen that forms the peptide backbone of the palmitoylated cosmetic ingredient Matrixyl.
KTTKS is not Matrixyl. Matrixyl is the palmitoylated derivative, Pal-KTTKS, and N-palmitoylation adds C16H30O — 238.2297 Da — changing both the covalent structure and the physicochemical behaviour. 'Pentapeptide-4' alone does not distinguish them, which is why the sequence should always accompany the name.
Declared aliases and development codes: Pentapeptide-4, Collagen pentapeptide.
02
Molecular properties
| Molecular formula | C23H45N7O9 |
|---|---|
| Molecular mass | 563.65 Da |
| CAS Registry Number | 149128-48-3 |
| PubChem CID | 9959565 |
| One-letter sequence | KTTKS |
| Three-letter sequence | Lys–Thr–Thr–Lys–Ser–OH |
Five residues, all L, free at both termini. No palmitoylation, no ring, no metal.
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Structural characteristics
It was identified as residues 212 to 216 of the type I procollagen carboxyl-terminal propeptide, and as the minimum sequence within a larger propeptide subfragment that produced the reported matrix effect in fibroblasts. Two limits follow. Identifying an active synthetic five-residue segment does not establish that free KTTKS is routinely released as an endogenous product. And 'signal peptide' is a functional description, not identification of a receptor: no direct molecular target is established. Its relationship to GHK is shared matrix-derived provenance, not a shared precursor protein or receptor — the two come from different parent proteins.
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Molecular targets & mechanisms
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Analytical considerations
Tandem MS must distinguish KTTKS from sequence permutations, and the palmitoylated species should be tested for explicitly rather than accepting 'pentapeptide-4' as sufficient identity. Threonine stereochemistry is not resolved by intact mass. A collagen hydrolysate containing compatible amino acids is not evidence of a purified KTTKS molecule. A direct comparison of KTTKS and pal-KTTKS in hairless mouse skin found both degraded rapidly, the palmitoylated form more stable, and only the palmitoylated form detectable in skin layers. Neither compound was detected in the receptor solution under the experimental conditions, so retention in skin layers should not be read as full-thickness permeation.
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Verified bibliography
- A pentapeptide from type I procollagen promotes extracellular matrix production.current
Katayama K, Armendariz-Borunda J, Raghow R, Kang AH, Seyer JM
The Journal of biological chemistry · 1993-05-15 · Journal Article
- Dermal Stability and In Vitro Skin Permeation of Collagen Pentapeptides (KTTKS and palmitoyl-KTTKS).current
Choi YL, Park EJ, Kim E, Na DH, Shin YH
Biomolecules & therapeutics · 2014-07 · Journal Article
- Development of a LC-MS/MS method to monitor palmitoyl peptides content in anti-wrinkle cosmetics.current
Chirita RI, Chaimbault P, Archambault JC, Robert I, Elfakir C
Analytica chimica acta · 2009-03-20 · Journal Article
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Methodology & citation verification
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