What Is GHK-Cu? The Copper Tripeptide: Structure, CAS Numbers and Research Literature

By the Zen Well Labs Research Team · Last reviewed September 2026 · For laboratory research reference only

Short answer: GHK-Cu is the copper(II) complex of the tripeptide glycyl-L-histidyl-L-lysine (Gly-His-Lys). The free peptide, GHK, has the formula C₁₄H₂₄N₆O₄, a molecular weight of 340.4 Da and CAS number 49557-75-7; the copper complex is registered under CAS 89030-95-5. GHK was first isolated from human plasma by Loren Pickart in 1973. It is widely studied in cell-culture models of extracellular-matrix biology and gene expression. Zen Well Labs sells GHK-Cu for in-vitro laboratory research only.

GHK-Cu at a glance

Common names	GHK-Cu, copper tripeptide-1, copper peptide, prezatide copper
Peptide sequence	Gly-His-Lys (GHK)
Free peptide formula / MW	C₁₄H₂₄N₆O₄ / 340.4 Da
CAS (free GHK peptide)	49557-75-7
CAS (GHK-Cu complex)	89030-95-5
Mass of 1:1 copper complex	≈402–404 Da, depending on protonation state and how the complex is written; acetate salt forms are heavier
Appearance	Blue to blue-violet powder or solution (characteristic of Cu(II) coordination)
Typical supplied form	Lyophilized powder

Where does GHK come from?

Pickart and Thaler reported in 1973 (Nature New Biology) that a small plasma factor altered the behaviour of cultured liver cells; the factor was identified as the tripeptide Gly-His-Lys. GHK has a very high affinity for copper(II), and in biological fluids it is thought to exist substantially as the copper complex. The histidine imidazole nitrogen, the glycine amino group and the deprotonated Gly-His amide nitrogen coordinate the copper ion, which is what gives the compound its blue colour.

What has the published research looked at?

Extracellular-matrix synthesis in fibroblast culture. Work from Maquart and colleagues in the late 1980s and 1990s reported increased collagen and glycosaminoglycan synthesis in cultured fibroblasts exposed to GHK-Cu.
Gene-expression profiling. Pickart and Margolina (International Journal of Molecular Sciences, 2018) reviewed Connectivity Map data in which GHK altered the expression of a large number of human genes in cell lines.
Copper transport and redox chemistry. GHK is used as a model ligand for studying how small peptides bind and deliver Cu(II).
Cosmetic science. GHK-Cu (INCI: copper tripeptide-1) is a common cosmetic ingredient, and there is a body of topical-formulation literature. That is a separate regulatory category from the research-grade material discussed here.

As with most research peptides, the strongest data are in vitro. GHK-Cu is not an FDA-approved drug.

Handling notes specific to GHK-Cu

Colour is expected. A blue powder or solution is normal. A colourless solution suggests free GHK without copper, or a very dilute solution.
pH matters. Copper binding is pH-dependent; strongly acidic conditions release Cu(II) from the peptide.
Avoid chelators. Buffers containing EDTA or other strong chelators will strip copper from the complex and change what you are actually testing.
Mind the redox chemistry. Reducing agents can reduce Cu(II); consider this when designing assay buffers.
Store lyophilized powder sealed, dry and dark at −20 °C. See our storage and stability guide.

Frequently asked questions

What does GHK-Cu stand for?

GHK is the one-letter amino-acid code for the tripeptide glycine-histidine-lysine; Cu is the chemical symbol for copper. GHK-Cu is the copper(II) complex of that tripeptide.

What is the CAS number of GHK-Cu?

The copper complex is registered under CAS 89030-95-5. The free GHK peptide without copper is CAS 49557-75-7.

Why is GHK-Cu blue?

The blue colour comes from the copper(II) ion coordinated by nitrogen atoms of the peptide. It is a normal property of the compound, not a sign of contamination.

Is GHK-Cu naturally occurring?

GHK was first isolated from human plasma in 1973. Research-grade GHK-Cu is produced synthetically.

Is GHK-Cu the same as the copper peptide in cosmetics?

The molecule is the same (INCI name copper tripeptide-1), but cosmetic ingredients and research reagents are different product categories with different specifications and intended uses. Zen Well Labs GHK-Cu is sold for in-vitro laboratory research only.

References

Pickart L, Thaler MM. Tripeptide in human serum which prolongs survival of normal liver cells and stimulates growth in neoplastic liver. Nature New Biology. 1973;243:85–87.
Maquart FX, et al. Stimulation of collagen synthesis in fibroblast cultures by the tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu2+. FEBS Letters. 1988;238(2):343–346.
Pickart L, Margolina A. Regenerative and protective actions of the GHK-Cu peptide in the light of the new gene data. International Journal of Molecular Sciences. 2018;19(7):1987.

Research use only. All products sold by Zen Well Labs are intended strictly for in-vitro laboratory research. They are not drugs, foods, cosmetics or dietary supplements, are not approved by the FDA for any use, and are not for human or veterinary use. Nothing on this page is medical advice, and nothing here describes or recommends administration to humans or animals.