GHK-Cu is the copper(II) complex of the tripeptide glycyl-L-histidyl-L-lysine (GHK). Often called simply "copper peptide" or "GHK copper peptide", it is one of the most widely studied small metal-peptide complexes in the laboratory literature, with research spanning coordination chemistry, cell culture and rodent models since the early 1970s. This overview covers its structure, identity data, CAS number, the history of its discovery and a neutral summary of what has been investigated.
For laboratory research use only. Not for human or veterinary use. See our research use only policy.
At a glance
- Name: GHK-Cu (glycyl-L-histidyl-L-lysine copper(II) complex)
- Synonyms: Copper peptide, GHK copper peptide, copper tripeptide-1, prezatide copper
- Sequence: Gly-His-Lys, copper(II) complex
- Molecular formula: C14H22CuN6O4 (neutral complex, per PubChem; salt forms differ)
- Molecular weight: approximately 401.9 g/mol (neutral complex, per PubChem)
- CAS number: 89030-95-5
- Purity: >99% (HPLC)
- Form: Lyophilised powder
- Storage: 2-8°C, dark, upright - do not freeze. Keep sealed until use.
Compound Cave supplies GHK-Cu in two vial sizes: GHK-Cu 50mg and GHK-Cu 100mg. Both carry the same identity data and the same storage guidance.
What is GHK-Cu?
At its core, GHK-Cu is two things combined: a very short peptide and a single copper ion. The peptide part, GHK, is a tripeptide made of three amino acids joined in the order glycine, histidine, lysine. On its own the free peptide is a colourless compound with its own CAS number, 49557-75-7. When GHK binds a copper(II) ion it forms a stable complex with a distinct blue to violet colour, and that complex is what researchers refer to as GHK-Cu.
The distinction between the free tripeptide and the copper complex matters for anyone sourcing or analysing the material, because the two have different formulas, different molecular weights, different CAS numbers and different appearance. We cover this in more depth in GHK vs GHK-Cu: the free tripeptide vs the copper complex.
Why it is called a copper peptide
"Copper peptide" is a general label for any peptide that coordinates a copper ion. In practice, when the phrase is used without further qualification it almost always refers to GHK-Cu, because GHK has an unusually high affinity for copper(II) and is by far the most researched example. Other copper-binding peptides exist, including longer sequences derived from albumin and other proteins, but none has attracted a comparable volume of published work.
Discovery and history
GHK was first described by Loren Pickart and Martin Thaler in 1973. Working with human plasma, they reported a small factor that altered the behaviour of liver cells in culture, and this factor was later identified as the tripeptide glycyl-histidyl-lysine. Subsequent work established that the peptide had a strong affinity for copper(II), and that much of the activity observed in those early culture experiments appeared to be associated with the copper-bound form.
Through the 1980s, research groups characterised the copper binding chemistry in detail. A 1981 study by Lau and Sarkar in the Biochemical Journal examined how copper(II) interacts with GHK in solution, and a 1988 paper by Maquart and colleagues in FEBS Letters reported effects of the copper complex on collagen synthesis in fibroblast cultures. These papers became frequently cited foundations for later laboratory work.
Since then, GHK-Cu has been investigated in a wide range of in vitro systems and rodent models. More recent reviews, notably by Pickart and Margolina in 2018, have discussed gene expression data in which GHK was reported to be associated with changes in the expression of a large number of genes in published datasets. These reviews are useful entry points to the literature, although readers should note that they summarise findings from many different model systems and do not establish any effect in humans.
Structure and coordination chemistry
The tripeptide backbone
GHK is about as small as a functional peptide gets. Glycine contributes a free N-terminal amine, histidine contributes an imidazole side chain, and lysine contributes a long side chain ending in a primary amine plus the C-terminal carboxyl group. The free peptide has the formula C14H24N6O4 and a molecular weight of roughly 340.4 g/mol according to PubChem.
How copper binds
Copper(II) binding in GHK is usually described as involving the N-terminal amine of glycine, the deprotonated amide nitrogen between glycine and histidine, and a nitrogen of the histidine imidazole ring. This arrangement creates a compact, square-planar style chelate around the copper ion, with the remaining coordination positions available to water, other ligands, or groups from neighbouring molecules. Studies of the solution chemistry, including the work of Lau and Sarkar, explored how this binding changes with pH.
Binding of copper releases two protons from the peptide, which is why the neutral complex formula (C14H22CuN6O4) has two fewer hydrogens than the free peptide. Commercial material may also be supplied as a salt, for example with acetate or chloride counterions, and the formula and molecular weight on any given batch document can differ accordingly. When comparing supplier data, it is worth checking which form is being described.
Colour as a structural clue
The blue to violet colour of GHK-Cu comes from d-d electronic transitions of the copper(II) ion in its peptide environment. It is a convenient visual check: a colourless or green-tinged powder labelled as GHK-Cu would warrant a closer look. Colour is not a substitute for analytical testing, but it is an informative first observation. Our article on handling copper peptides in the lab goes into colour, stability and storage in more detail.
The CAS number for GHK-Cu
The CAS registry number most widely associated with the GHK-Cu complex is 89030-95-5. The free tripeptide GHK has the separate CAS number 49557-75-7. Because the two numbers are frequently mixed up in online listings, it is good practice to confirm that the CAS number on a product page, label or certificate actually matches the form of the material described. If a listing says "GHK-Cu" but quotes 49557-75-7, it is referring to the free peptide's registry entry, not the complex.
For a general guide to checking identity and purity documents, see how to read a peptide certificate of analysis.
Research overview
The published literature on GHK-Cu is broad. The summary below groups the main areas of laboratory investigation. It is descriptive only: it reports what has been studied and what authors stated at the time, and it draws no conclusions about effects in humans.
Cell culture studies
A large share of the GHK-Cu literature comes from in vitro work. Fibroblast cultures have been the most common model. The 1988 Maquart study reported increased collagen synthesis in fibroblast cultures exposed to the copper complex, and later papers investigated glycosaminoglycan production, matrix metalloproteinase activity and related extracellular matrix markers. Other groups examined GHK-Cu in keratinocyte, endothelial and nerve-derived cell lines.
Rodent and other animal models
GHK-Cu has been investigated in rodent models of tissue repair, in which researchers reported measurements such as tissue contraction rates, collagen deposition and blood vessel formation. Studies in other species have also appeared in the literature. Experimental designs, concentrations and endpoints vary widely between these papers, which makes direct comparison difficult.
Gene expression analyses
More recent publications have used existing gene expression datasets, such as the Broad Institute's Connectivity Map, to examine which genes were reported to change in expression in the presence of GHK. Pickart and colleagues discussed these analyses in reviews published in 2015 and 2018. These are computational analyses of cell line data and should be read as hypothesis-generating rather than as evidence of any physiological effect.
Copper transport and biochemistry
Because GHK binds copper so tightly, some research has focused on its possible role in copper transport and copper exchange with proteins such as albumin. This area overlaps with the wider field of copper biochemistry and remains an active topic in the coordination chemistry literature.
Related compounds and blends
GHK-Cu is also found as a component of multi-peptide research blends. The best known are the so-called Glow and Klow blends, which combine GHK-Cu with other peptides. We explain the typical composition of each and how they differ in Glow vs Klow peptide blends. The non-copper peptides commonly found in those blends are covered in our BPC-157 and TB-500 research overview and our article on KPV peptide.
Researchers interested in other short synthetic peptides studied in similar in vitro skin-cell contexts may also find our overview of SNAP-8 peptide useful. SNAP-8 is unrelated to GHK-Cu structurally: it is an acetylated octapeptide with no metal centre, derived from a protein involved in vesicle fusion.
Quality and analytical considerations
Analysing a metal-peptide complex brings a few considerations that do not apply to a simple linear peptide.
- HPLC purity: reversed-phase HPLC is the standard purity method. Copper complexes can partially dissociate under acidic mobile phase conditions, so the chromatogram may reflect the free peptide as much as the complex. This is normal and is why method details matter.
- Mass spectrometry: ESI-MS of GHK-Cu may show signals for the free peptide (around 341 m/z for the protonated ion) alongside copper-containing species, depending on conditions.
- Copper content: some laboratories confirm copper stoichiometry separately, for example by elemental analysis or ICP methods, since HPLC and MS alone may not fully characterise the metal content.
- Appearance: a uniform blue to violet lyophilised powder is expected. Discolouration or clumping can indicate moisture uptake.
Compound Cave GHK-Cu is specified at >99% purity by HPLC. For general background on interpreting purity figures, our guide to research peptides in the UK covers purity, testing and compliance.
Storage and handling
Like most lyophilised peptides, GHK-Cu is best kept dry, cool and away from light. Our storage guidance for both vial sizes is 2-8°C, dark, upright, not frozen, and kept sealed until use. Copper complexes are sensitive to strong chelating agents and reducing agents, which can strip or change the oxidation state of the copper, so these should be kept away from the material. A fuller discussion is in our article on handling copper peptides in the lab, and general principles for all freeze-dried peptides are in how to store lyophilised peptides.
Regulatory position in the UK
GHK-Cu supplied by Compound Cave is a laboratory research material. It is not a medicine, it has not been assessed by the MHRA for any medicinal use, and it is not sold for human or veterinary use. Copper tripeptide ingredients do appear in some cosmetic product formulations, which are regulated under separate cosmetics rules, but that is a different category of product with different manufacturing and safety requirements. Our research material is not a cosmetic ingredient. For more on how UK rules apply to research peptides, see are peptides legal in the UK.
Summary
GHK-Cu is the copper(II) complex of the naturally occurring tripeptide Gly-His-Lys. It is identified by CAS 89030-95-5, distinct from the free peptide at 49557-75-7, and is recognisable by its blue to violet colour. Its research history runs from the 1973 discovery of GHK in plasma through decades of coordination chemistry, cell culture and rodent studies to recent gene expression analyses. Anyone working with the material should pay attention to which form is being described, how purity was measured, and how the copper complex is stored.
View GHK-Cu 50mg or GHK-Cu 100mg in the catalogue.
Frequently asked questions
What is the CAS number of GHK-Cu?
The CAS number most widely associated with the GHK-Cu copper complex is 89030-95-5. The free tripeptide GHK, without copper, has the separate CAS number 49557-75-7.
Is GHK-Cu the same as copper peptide?
"Copper peptide" is a general term for any copper-binding peptide, but in common usage it almost always refers to GHK-Cu, the copper(II) complex of glycyl-histidyl-lysine.
What colour should GHK-Cu be?
GHK-Cu is typically a blue to violet lyophilised powder. The colour comes from the copper(II) ion in its peptide environment. The free GHK peptide is colourless.
Where does GHK come from?
GHK was first reported in human plasma by Pickart and Thaler in 1973. Research-grade material is produced synthetically and then complexed with copper.
How should GHK-Cu be stored?
Our guidance is 2-8°C, dark, upright, not frozen, and kept sealed until use. Keep it away from moisture, strong chelating agents and reducing agents.
Is GHK-Cu a medicine?
No. Compound Cave GHK-Cu is a laboratory research material only. It is not a medicine and is not for human or veterinary use.
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.
- Lau SJ, Sarkar B. The interaction of copper(II) and glycyl-L-histidyl-L-lysine, a growth-modulating tripeptide from plasma. Biochemical Journal, 1981.
- Maquart FX, Pickart L, Laurent M, Gillery P, Monboisse JC, Borel JP. Stimulation of collagen synthesis in fibroblast cultures by the tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu2+. FEBS Letters, 1988.
- Pickart L, Vasquez-Soltero JM, Margolina A. GHK peptide as a natural modulator of multiple cellular pathways in skin regeneration. BioMed Research International, 2015.
- 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.
- PubChem compound records for glycyl-L-histidyl-L-lysine and its copper(II) complex, National Center for Biotechnology Information.
For laboratory research use only. Not for human or veterinary use. See our research use only policy.