By BioLabs Research · Last reviewed: October 10, 2026
GHK is the tripeptide glycine–histidine–lysine (Gly-His-Lys). GHK-Cu is that tripeptide bound to a copper(II) ion. The free peptide and the copper complex are different reagents, with different formulae, masses and appearance. This page covers identity, the coordination chemistry, where GHK sits in the literature, quality markers and storage for the GHK-Cu catalog listing, a laboratory reagent.
Identity at a glance
| Field | Free GHK | GHK-Cu (copper complex) |
|---|---|---|
| Composition | Gly-His-Lys tripeptide | Gly-His-Lys + Cu(II) |
| Molecular formula | C14H24N6O4 (PubChem CID 73587) | Depends on how the complex, its charge and counter-ions are written (PubChem CID 139035031 lists C14H21CuN6O4−) |
| Molecular weight | ≈340.4 g/mol | ≈400.9 g/mol for the 1:1 complex as listed in PubChem CID 139035031, before counter-ions |
| Typical appearance | White to off-white solid | Blue solid |
A common error is to print the free tripeptide's weight (≈340 g/mol) as the weight of the copper complex. The complex is heavier. Commercial material may also include counter-ions such as acetate or chloride. The lot certificate should therefore state the exact form: free peptide or copper complex, which salt, and the copper-to-peptide ratio.
How copper binds
GHK binds Cu(II) tightly. Structural work has solved its copper complex by X-ray crystallography and studied it in solution. In the main complex, copper is held by the N-terminal amine of glycine, the deprotonated amide nitrogen of the Gly–His peptide bond, and an imidazole nitrogen of histidine (Hureau et al., 2011). The same study examined the redox behavior of the complex. For a lab, the practical point is simple: copper content and the copper-to-peptide ratio are identity fields, not optional extras.
Where GHK sits in the literature
The GHK sequence was first reported in 1973 by Pickart and Thaler, who isolated it from human serum during cell-culture work on liver cells (Pickart & Thaler, 1973). Since then, GHK has become a standard model in copper coordination chemistry: a short, well-defined peptide that shows how histidine-containing sequences bind copper and how the resulting complexes behave in redox reactions (Hureau et al., 2011).
That history explains why the identity record matters so much. A tripeptide of about 340 Da and a copper complex of about 400 Da are both called "GHK" in casual use, so every record needs to say which one it means. Lot paperwork should make that choice explicit on the first line, before any purity or mass figure is given.
Why the free peptide and the complex get confused
Three habits commonly lead to paperwork errors with this material:
- One name for two materials. "GHK" and "GHK-Cu" are used interchangeably on labels and in spreadsheets, so a certificate for the free peptide can end up filed against a vial of the complex.
- Borrowed molecular weights. Public tables often list the free peptide first. Copying the first number into a COA template gives the complex the wrong weight.
- Silent counter-ions. Acetate or chloride salts add mass that a bare formula leaves out. Without a salt statement, two correct-looking certificates for the same material can disagree.
The fix in each case is the same: one name per material in the inventory system, one formula weight that matches the stated form, and a certificate that names the salt and the copper content alongside the mass.
Quality markers specific to GHK-Cu
- Complex vs free peptide. The certificate should confirm the copper-complexed form, not just the GHK peptide.
- Copper content. Look for a stated copper percentage, or a copper-to-peptide ratio, with the method used.
- Identity by mass spectrometry. Spectra can show the free peptide (about 340 Da) and copper-containing ions. The certificate should explain which ions were assigned.
- Purity by HPLC. Ask for the method ID, column and wavelength.
- Counter-ion and water. Salt form changes the formula weight. See HPLC area percent vs net peptide content.
- Appearance. Expect a blue color for the copper complex. A white powder sold as "GHK-Cu" calls for questions.
Our guide on how to read lot documents shows where each of these fields sits on a certificate, and the COA library has complete examples for catalog listings.
Handling and storage as laboratory material
- Store sealed vials cold (−20 °C is typical), dry and away from light, as the lot paper states.
- Limit humidity and repeated warming. Copper complexes take part in redox chemistry, so keep the material away from strong reducing or oxidizing agents during storage.
- Record receipt date, storage location and lot number against the certificate.
- Follow institutional rules for copper-containing waste.
Receiving checklist for a GHK-Cu lot
Before the vial goes into stock, confirm:
- The carton, the order and the invoice name the same catalog listing.
- The lot number on the vial appears on the certificate.
- The certificate states the copper-complexed form, the salt, and the copper content or copper-to-peptide ratio.
- Mass spectrometry results are assigned, and the HPLC method is identified.
- The material is blue and the vial is sealed and dry.
If the certificate describes only free GHK, or omits copper content, record the lot as "identity unresolved" and ask for a revised certificate.
Next step: Request the lot certificate for the GHK-Cu listing before you order.
Related reading
References
- Pickart L, Thaler MM. Nat New Biol. 1973;243(124):85–87. https://pubmed.ncbi.nlm.nih.gov/4349963/
- Hureau C, Eury H, Guillot R, et al. X-ray and solution structures of Cu(II) GHK and Cu(II) DAHK complexes: influence on their redox properties. Chemistry. 2011;17(36):10151–10160. https://pubmed.ncbi.nlm.nih.gov/21780203/
- PubChem Compound Summary, CID 73587 (Gly-His-Lys): C14H24N6O4, MW 340.38. https://pubchem.ncbi.nlm.nih.gov/compound/73587
- PubChem Compound Summary, CID 139035031 (copper tripeptide record): C14H21CuN6O4−, MW 400.9. https://pubchem.ncbi.nlm.nih.gov/compound/139035031
For research use only. Not for human or veterinary use.