Copper Peptides
Explained

What are copper peptides?

Copper peptides are short peptides holding a copper(II) ion. The best-characterized begin NH₂-Xxx-His or NH₂-Xxx-Zzz-His, where Xxx and Zzz can be any residue; Gly-His-Lys (GHK) and Asp-Ala-His-Lys (DAHK) are the canonical examples (Gonzalez et al., 2017). In research catalogs the term usually means GHK-Cu, the copper complex of a tripeptide found in human blood (Pickart and Thaler, 1973; Pickart et al., 1980), and its synthetic analog AHK-Cu. Disguised Alpha supplies GHK-Cu (50MG and 100MG) and AHK-Cu (100MG) as lyophilized powders for laboratory research use only. Nothing on this page is guidance for use in people.

How a peptide binds copper

Both motifs need a free N-terminal amine, and the position of the first histidine sets the shape of the complex (Gonzalez et al., 2017):

• Histidine at position 2 (NH₂-Xxx-His), as in GHK: three peptide nitrogens plus one outside ligand around the copper, called the 3N form.
• Histidine at position 3 (NH₂-Xxx-Zzz-His), as in DAHK, the N-terminal sequence of human serum albumin: four peptide nitrogens, called the 4N form; this sequence type is also known as the ATCUN motif.

In solution, Cu(II)GHK is a monomer held by the free amine, one deprotonated backbone amide nitrogen and the histidine imidazole, with a labile fourth position. Cu(II)DAHK uses the amine, two amide nitrogens and the imidazole (Hureau et al., 2011). Both bind tightly: calorimetry measured mainly 1:1 complexes, with conditional dissociation constants (Kd) at pH 7.4 of 7.0 × 10⁻¹⁴ M for GHK and 2.6 × 10⁻¹⁴ M for DAHK (Trapaidze et al., 2012).

The lysine contributes too. In titrations its side-chain amino group raised the stability constants compared with Gly-His and Gly-His-Gly, and in equilibrium dialysis at pH 7.5 the tripeptide held about 42 percent of the copper against an equal molar amount of albumin (Lau and Sarkar, 1981).

The discovery of GHK in human plasma

Pickart and Thaler reported in 1973 a tripeptide in human serum that prolonged the survival of normal liver cells and stimulated growth in neoplastic liver (Pickart and Thaler, 1973). The peptide was later identified as glycyl-L-histidyl-L-lysine, abbreviated GHL in early papers.

In 1980 the group reported that it co-isolated from plasma with roughly equimolar copper and about one fifth molar iron, and that at nanomolar concentrations it produced responses in cultured systems ranging from growth to outright toxicity. It readily formed copper(II) complexes and raised copper uptake into cultured hepatoma cells, several tripeptides with a histidyl-lysyl linkage were nearly as active, and its likeness to the copper transport sites of albumin led the authors to propose a copper transport role (Pickart et al., 1980).

Copper peptides at a glance

Data come from the studies cited on this page.

Copper peptides research: cell and animal models

Almost all published work concerns GHK and GHK-Cu. The studies summarized here are cell, tissue, animal and computational work.

Fibroblast and collagen-gene work

In fibroblast cultures, GHK-Cu raised collagen synthesis starting between 10⁻¹² and 10⁻¹¹ M, maximal at 10⁻⁹ M and independent of cell number; the Gly-His-Lys triplet occurs in the α2(I) chain of type I collagen (Maquart et al., 1988). Another fibroblast study separated metal from peptide: GHK-Cu raised matrix metalloproteinase-2 (MMP-2) levels in the medium, MMP-2 mRNA and TIMP-1 and TIMP-2 secretion, and copper ions alone reproduced the MMP-2 increase while GHK alone did not (Siméon et al., 2000).

Wound models in animals

In implanted rat wound chambers, GHK-Cu produced concentration-dependent increases in dry weight, DNA, protein, collagen and glycosaminoglycans. Type I and type III collagen mRNAs rose, TGF-β mRNA did not, and a control tripeptide had no significant effect (Maquart et al., 1993). Later work in this model is summarized in our GHK-Cu research guide.

Gene-expression and Connectivity Map studies

The Connectivity Map matches disease gene-expression signatures against profiles of cultured human cells exposed to small molecules. Profiling lung tissue from smokers with COPD, one team found 127 genes tied to emphysema severity and identified GHK as reversing that signature. In human fibroblasts, GHK reproduced TGF-β-like expression patterns and restored collagen I contraction by fibroblasts from COPD lungs (Campbell et al., 2012). A colorectal cancer study that queried a metastasis signature returned Gly-His-Lys and securinine as reversing it, a computational match only (Hong et al., 2010). Both studies name the tripeptide GHK, not its copper complex.

AHK-Cu: what is published

AHK-Cu is the copper(II) complex of L-alanyl-L-histidyl-L-lysine. Alanine replaces glycine at the first residue, adding one CH₂ unit: free AHK is C₁₅H₂₆N₆O₄, 354.41 g/mol (PubChem CID 7408502), against 340.38 g/mol for free GHK (CID 73587). It keeps the NH₂-Xxx-His start and the His-Lys pair, and PubChem's AHK-Cu record (CID 168431292) names the same three donor nitrogens as GHK-Cu. We found no measured binding constant for AHK in PubMed.

A PubMed search for AHK-Cu in October 2026 returned one primary study. Researchers exposed human hair follicles in organ culture, and cultured dermal papilla cells, to AHK-Cu at 10⁻¹² to 10⁻⁹ M and reported follicle elongation and cell proliferation. At 10⁻⁹ M the Bcl-2/Bax ratio rose and cleaved caspase-3 and PARP fell, though a drop in apoptotic cells was not statistically significant (Pyo et al., 2007). These are ex vivo and cell data from one laboratory. The product page lists a hydrochloride form, C₁₅H₂₄ClCuN₆O₄⁻ at 451.39 g/mol; confirm the form on the lot certificate.

Stability and handling of copper peptides

Color as a check

At pH 7.4, Cu(II)GHK absorbs in a d-d band near 606 nm, in the orange part of the spectrum, which is why its solutions look blue; a 4N complex such as Gly-Gly-His amide absorbs near 525 nm. Imidazole shifted the GHK band to 565 nm as a mixed complex formed, and glutathione weakened it as copper(II) became copper(I) (Ufnalska et al., 2021). A color change signals that the copper's surroundings have changed.

pH, chelators and reducing agents

Copper binding shifts with pH: titrations from pH 3.5 to 10.6 found several copper species rather than one (Lau and Sarkar, 1981). GHK-Cu stayed stable in water and pH 4.5 to 7.4 buffers for at least two weeks at 60°C but was cleaved under basic and oxidative stress, with histidine among the degradation products (Badenhorst et al., 2016).

The copper is not locked in place. Cu(II)GHK exchanged copper quickly, unlike DAHK, and formed mixed complexes with glycine or histidine (Hureau et al., 2011), and the calorimetry study corrected for glycine and HEPES buffer as competing chelators (Trapaidze et al., 2012). Glutathione reduced most of the copper(II) to copper(I) under the study conditions, and with 2-mercaptoethanol an insoluble copper(I) species precipitated (Ufnalska et al., 2021).

Lab practice

• Store the powder at -20°C, protected from light, and reconstituted solutions at 2 to 8°C without freeze/thaw cycles, as listed on the GHK-Cu and AHK-Cu product pages.
• Prepare stock in water or a pH 4.5 to 7.4 buffer, away from oxidizers.
• Keep EDTA and other chelators, thiols, and high levels of histidine, imidazole or glycine out of stock solutions unless the experiment calls for them.
• Calculate from the formula and measured content on the lot certificate.

Regulatory status and other uses of the name

Drugs@FDA lists no product containing GHK, GHK-Cu (prezatide copper) or AHK-Cu (openFDA search, October 2026). An FDA page on bulk drug substances for compounding that may present significant safety risks, current as of April 2026, lists GHK-Cu for injectable routes among former category 2 substances whose nominations were withdrawn, citing possible immunogenicity from aggregation and peptide-related impurities and limited human data. Outside the laboratory, "copper peptide" is also a cosmetic ingredient term, and PubChem lists copper tripeptide-1 as the ingredient name for GHK-Cu (CID 71587328); this page makes no claims about such products.

Key sources

1. Pickart L, Thaler MM. "Tripeptide in human serum which prolongs survival of normal liver cells and stimulates growth in neoplastic liver." Nat New Biol. 1973. PMID 4349963. No abstract in PubMed.
2. Pickart L, et al. "Growth-modulating plasma tripeptide may function by facilitating copper uptake into cells." Nature. 1980. PMID 7453802. DOI 10.1038/288715a0.
3. 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. DOI 10.1002/chem.201100751.
4. Gonzalez P, et al. "Cu(II) Binding to the Peptide Ala-His-His, a Chimera of the Canonical Cu(II)-Binding Motifs Xxx-His and Xxx-Zzz-His." Inorg Chem. 2017. PMID 29190078. DOI 10.1021/acs.inorgchem.7b01996.

Frequently asked questions

What are copper peptides?

Short peptides that hold a copper(II) ion, usually through the N-terminal amine, a backbone amide nitrogen and a histidine. GHK-Cu, first isolated from human plasma, is the best-known example (Pickart et al., 1980).

What is the GHK copper peptide?

GHK-Cu is the tripeptide glycyl-L-histidyl-L-lysine bound to one copper(II) ion, with a conditional dissociation constant of about 7 × 10⁻¹⁴ M at pH 7.4 (Trapaidze et al., 2012). See our GHK-Cu research guide.

What is a copper tripeptide?

A three-residue peptide complexed with copper. GHK-Cu and AHK-Cu are both copper tripeptides, and PubChem lists "copper tripeptide-1" as a name for GHK-Cu (CID 71587328).

Why is GHK-Cu blue?

The bound copper(II) absorbs orange light, in a band near 606 nm at pH 7.4, so solutions look blue. Reducing the copper or changing its ligands weakens or shifts that band (Ufnalska et al., 2021).

GHK-Cu vs AHK-Cu: what is the difference?

One residue: AHK-Cu has alanine where GHK-Cu has glycine, and both keep the His-Lys pair. GHK and GHK-Cu appear in several hundred PubMed records, AHK-Cu in one primary study (Pyo et al., 2007). See our GHK-Cu vs AHK-Cu comparison.

Is GHK-Cu FDA approved?

No. Drugs@FDA lists no product containing GHK-Cu or AHK-Cu (openFDA search, October 2026).

Where can researchers buy copper peptides?

Disguised Alpha lists GHK-Cu (50MG and 100MG), AHK-Cu (100MG) and the GHK-Cu blends GLOW, KLOW and GHK-Cu / KPV, with lot certificates on each product page and in the COA portal.

Related guides

• GHK-Cu research guide
• AHK-Cu research guide
• GHK-Cu vs AHK-Cu comparison
• GLOW vs KLOW comparison
• KLOW research guide
• What is a peptide?
• What does lyophilized mean?
• What is a COA?
• COA portal: published certificates, by lot
• Research hub

Disguised Alpha products are for research use only. They have not been evaluated for safety or effectiveness in humans. Not for human consumption. All products are intended for laboratory research purposes only.