What Is GHK-Cu? The Copper Tripeptide Explained

GHK-Cu is the copper(II) complex of GHK, a tripeptide (glycyl-L-histidyl-L-lysine) that occurs naturally in human plasma. GHK binds copper with high affinity, and the complex has been studied for decades in fibroblast, wound and gene-expression research. Unusually for a peptide, its most prominent research and commercial use is in topical skin science.

For laboratory research use only. The compounds discussed are not approved for human or veterinary use and are not drugs, foods or cosmetics. This article summarises published research and is not medical advice.

Key points

Peptide: Gly-His-Lys, 340.4 g/mol; binds one Cu(II) ion via three nitrogen atoms.
Endogenous: found in plasma, where it can also form ternary complexes with albumin.
Cell studies: extracellular-matrix synthesis and remodelling in dermal fibroblasts.
Very hydrophilic and chemically robust in mildly acidic to neutral water.
Blue colour is intrinsic to the copper complex.

Quick facts

Property	Value
Peptide sequence	Gly-His-Lys (GHK)
Peptide formula / weight	C₁₄H₂₄N₆O₄, 340.4 g/mol
Metal	Copper(II), 1:1 complex in solution
Copper ligands (solution)	N-terminal NH₂, a backbone amide N, His imidazole N
Hydrophilicity	log D about −2.4 at pH 4.5–7.4
Appearance	Blue to violet-blue powder and solution

Lot data for our GHK-Cu copper peptide (50 mg and 100 mg) are published with each batch.

How GHK binds copper

A combined X-ray and spectroscopic study showed that Cu(II)-GHK is dimeric in the solid state but forms a monomeric complex in solution. Copper is held by three nitrogen ligands: the N-terminal amine, a deprotonated backbone amide nitrogen and the histidine imidazole. The fourth position is occupied by a labile oxygen donor. Unlike some other plasma copper-binding peptides, GHK exchanges copper quickly (Hureau et al., 2011). In plasma, GHK is most concentrated in the albumin-rich fraction, and two ternary albumin–Cu–GHK complexes have been characterised, which may help transport exchangeable copper (Bossak-Ahmad et al., 2021).

What cell and gene studies report

Area	Finding	Study
Matrix remodelling	GHK-Cu increased MMP-2 and the inhibitors TIMP-1 and TIMP-2 in dermal fibroblast cultures; the MMP-2 effect was reproduced by copper ions but not by GHK alone	Siméon et al., 2000
Gene expression	Analyses of gene-expression data link GHK to many pathways in tissue remodelling and protection	Pickart and Margolina, 2018
Metal-induced aggregation	GHK reduced copper redox activity and prevented copper- and zinc-induced protein aggregation and cell death in vitro	Min et al., 2024

Much of the broader GHK literature, including the 2018 review, comes from researchers associated with companies developing copper-peptide products. That does not invalidate it, but independent replication should be weighed when interpreting claims.

Stability

A preformulation study found GHK-Cu to be highly hydrophilic. It was stable in water and in pH 4.5–7.4 buffers for at least two weeks at 60 °C, while it degraded under basic and oxidative stress and, to a lesser extent, under acidic stress. Histidine was one of the identified degradation products (Badenhorst et al., 2016). This robustness explains its use in topical formulations, and for lab work it means solution stability is relatively forgiving within a neutral pH range.

Handling in the lab

Store lyophilized powder sealed at −20 °C (2–8 °C short-term), protected from light.
Reconstitute with water; solutions are blue. A colour change towards green or loss of colour suggests a problem with the complex.
Avoid strong bases, oxidants and chelators such as EDTA, which strip copper.
Calculate concentrations with the peptide reconstitution calculator; method in how to reconstitute peptides.

Open questions

How much of GHK’s reported activity depends on copper delivery versus the peptide itself? The MMP-2 result suggests copper is decisive for some effects.
Which findings replicate across independent groups? Much of the gene-expression interpretation comes from a small number of authors.
What is the functional role of the albumin–Cu–GHK ternary complexes identified in plasma?

For experimental design, including a free-copper control and a GHK-without-copper control helps separate these contributions.

Related research

Frequently asked questions

What is GHK-Cu?

GHK-Cu is the copper(II) complex of GHK, a naturally occurring tripeptide (glycyl-L-histidyl-L-lysine) found in human plasma. The peptide binds copper tightly and is studied for effects on fibroblasts, extracellular matrix and gene expression.

What is the difference between GHK and GHK-Cu?

GHK is the free tripeptide; GHK-Cu is GHK bound to a copper(II) ion. Some effects differ: in one fibroblast study, increased MMP-2 was reproduced by copper ions or GHK-Cu but not by GHK alone.

What does GHK-Cu do in cell studies?

In cultured dermal fibroblasts it has been reported to increase extracellular-matrix synthesis and to modulate matrix metalloproteinases and their inhibitors. Gene-expression analyses link GHK to many pathways involved in tissue remodelling.

Are copper peptides the same as GHK-Cu?

‘Copper peptide’ is a broad term. GHK-Cu is the best-known example; others include AHK-Cu (Ala-His-Lys-copper).

Why is GHK-Cu blue?

Copper(II) bound by nitrogen atoms of the peptide absorbs light in the red–orange region, so the powder and its solutions appear blue to violet-blue.

References

Pickart L, et al. Regenerative and Protective Actions of the GHK-Cu Peptide in the Light of the New Gene Data. Int J Mol Sci. 2018. PMID: 29986520 https://pubmed.ncbi.nlm.nih.gov/29986520/
Hureau C, et al. X-ray and solution structures of Cu(II) GHK and Cu(II) DAHK complexes: influence on their redox properties. Chemistry. 2011. PMID: 21780203 https://pubmed.ncbi.nlm.nih.gov/21780203/
Bossak-Ahmad K, et al. Ternary Cu(2+) Complexes of Human Serum Albumin and Glycyl-l-histidyl-l-lysine. Inorg Chem. 2021. PMID: 34730942 https://pubmed.ncbi.nlm.nih.gov/34730942/
Siméon A, et al. The tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu2+ stimulates matrix metalloproteinase-2 expression by fibroblast cultures. Life Sci. 2000. PMID: 11045606 https://pubmed.ncbi.nlm.nih.gov/11045606/
Min JH, et al. Glycyl-l-histidyl-l-lysine prevents copper- and zinc-induced protein aggregation and central nervous system cell death in vitro. Metallomics. 2024. PMID: 38599632 https://pubmed.ncbi.nlm.nih.gov/38599632/
Badenhorst T, et al. Physicochemical characterization of native glycyl-l-histidyl-l-lysine tripeptide for wound healing and anti-aging: a preformulation study for dermal delivery. Pharm Dev Technol. 2016. PMID: 25384620 https://pubmed.ncbi.nlm.nih.gov/25384620/