What Is GHK-Cu? The Copper Tripeptide Explained
What is GHK-Cu? In short, it is the copper complex of a three-amino-acid peptide, glycyl-L-histidyl-L-lysine. It is one of the most widely studied small peptides, appears in cosmetic ingredient lists as copper tripeptide-1, and is a staple of laboratory research on copper-binding peptides. This explainer covers its structure and history, how it binds copper, the research formats it comes in, and practical handling notes. It does not make claims about effects in people.
In this guide
What is GHK-Cu? Five facts at a glance
- Peptide: GHK, the tripeptide Gly-His-Lys
- Complex: GHK bound to a copper(II) ion
- Other names: copper tripeptide-1 (cosmetic ingredient name), prezatide copper
- Molecular formula of GHK: C14H24N6O4 (about 340 g/mol before copper is bound)
- Appearance: copper complexes of GHK are typically blue to blue-violet
PubChem lists the copper complex under prezatide copper.
How GHK was discovered
GHK was first reported in 1973 by Loren Pickart and colleagues, who were studying a factor in human plasma that affected the behaviour of liver cells in culture (Pickart and Thaler, Nature New Biology, 1973). The active factor was identified as the tripeptide glycyl-L-histidyl-L-lysine. Later work showed that GHK binds copper strongly, and the copper complex became the main form studied.
GHK occurs naturally in human plasma, saliva and urine. That natural occurrence is part of why it attracted so much research interest.
How GHK binds copper
GHK has a high affinity for copper(II). The metal is held mainly by nitrogen atoms from the glycine and histidine residues, including the imidazole ring of histidine, forming a compact, stable complex. Because GHK binds copper so strongly, it can take copper from weaker binding sites, which is why it is often discussed as a copper-transport or copper-delivery molecule in the research literature.
For laboratory work, the distinction between GHK (the free peptide) and GHK-Cu (the complex) matters, and it is central to answering what is GHK-Cu in a practical sense. Check which form you are buying and which form a protocol specifies.
Where GHK-Cu appears in research
GHK-Cu has been studied for decades in cell-culture and animal models, particularly around skin, connective tissue and tissue remodelling, and it is a common ingredient in cosmetic formulation research. A 2018 review by Pickart and Margolina summarises that body of work and adds analyses of gene-expression data (International Journal of Molecular Sciences, 2018).
Two cautions apply when reading this literature. First, much of it comes from cell and animal models, which do not establish effects in people. Second, a large share of the published work involves the peptide’s original discoverer, so independent replication is worth looking for. Nexaph supplies GHK-Cu strictly as a research material and makes no claims about its effects.
GHK-Cu and AHK-Cu
AHK-Cu is the copper complex of Ala-His-Lys. It differs from GHK-Cu by a single residue: alanine replaces glycine at the first position. The two are often compared in cosmetic-formulation research because the small change alters the peptide’s properties while keeping the histidine and lysine residues. Nexaph supplies AHK-Cu in cosmetic-grade 1g ampules.
Lyophilized vs cosmetic-grade formats
GHK-Cu is commonly supplied in two forms for research:
- Lyophilized vials: freeze-dried powder in small sealed vials, typically used for bench-scale research. Nexaph supplies GHK-Cu lyophilized as 50mg or 100mg per vial, 10 vials per kit.
- Cosmetic or topical grade: larger quantities intended for cosmetic-formulation work. Nexaph supplies GHK-Cu cosmetic grade as five 1g ampules.
GHK-Cu also appears in multi-peptide blends, which list each component’s amount per vial: Beauty Blend (GHK-Cu with KPV), Glow Blend (GHK-Cu, TB4 and BPC-157) and KLOW Blend (Glow’s three plus KPV).
What to check in GHK-Cu documentation
Because GHK-Cu is a peptide–metal complex, its documentation has a few extra points to check compared with an ordinary peptide:
- Peptide or complex? Confirm whether the identity and purity results refer to the free peptide GHK, the GHK-Cu complex, or both. Mass spectrometry can detect either, depending on conditions.
- Copper content: GHK and copper are usually combined in roughly a one-to-one molar ratio. A certificate that reports copper content lets you check that the material is the complex and not a mixture with excess free copper salt.
- Appearance: the expected blue to blue-violet colour is a quick visual check. Colourless material suggests free peptide; a strongly green tint is worth asking about.
- Counter-ions and water: as with other lyophilized peptides, these affect how much of the powder weight is the active complex.
If any of these points is not covered, ask the supplier before you rely on the batch. For Nexaph kits, quote the SKU (the batch code) when you email support. Our general guide to reading a peptide certificate of analysis covers the rest of the document.
Handling and storage notes
- Expect a blue colour. It comes from the copper complex and is normal.
- Store lyophilized GHK-Cu sealed, cold, dry and away from light, and let vials reach room temperature before opening. Our guide on how to store lyophilized peptides explains why.
- Record the batch code. For Nexaph kits, the SKU on the product page is the batch code; quote it to request documentation.
Frequently asked questions
Is GHK-Cu the same as copper tripeptide-1? Yes. Copper tripeptide-1 is the cosmetic ingredient name for the copper complex of GHK.
What is GHK-Cu: a peptide or a metal complex? Both: GHK is the peptide, and GHK-Cu is that peptide bound to copper(II).
Can GHK-Cu from Nexaph be used on people or animals? No. Nexaph products are sold for laboratory research only and are not for human or animal use. See what “research use only” means.
Explore the full copper and cosmetic peptides range. This article is for laboratory research and educational purposes and is not medical advice.