What Is GHK-Cu? Copper Peptide Chemistry and Research

GHK-Cu is a small copper-binding peptide complex formed from the tripeptide glycyl-L-histidyl-L-lysine (Gly-His-Lys, GHK) and a divalent copper ion (Cu²⁺). The GHK tripeptide itself has the molecular formula C₁₄H₂₄N₆O₄ and an average molecular weight of about 340.4 Da; the GHK-Cu complex is C₁₄H₂₁CuN₆O₄ with an average molecular weight of about 400.9 Da. It was first isolated from human plasma by Loren Pickart in 1973 and has since been studied in in-vitro and preclinical models of collagen synthesis, extracellular-matrix remodelling, gene-expression modulation, and antioxidant chemistry. GHK-Cu is not an FDA-approved drug; the research-grade material is sold under For Research Use Only labelling.

Updated August 30, 2026 · Peptide Research Guides · ~9 min read

GHK, GHK-Cu, and Copper Peptides — Getting the Terminology Right

Three names circulate in the literature and in vendor catalogs, and they refer to different chemical species. Getting the terminology right is the first step in reading any GHK-Cu study or COA correctly.

Term	What it refers to	Approximate MW	CAS
GHK	The free tripeptide glycyl-L-histidyl-L-lysine, no copper.	~340.4 Da (C₁₄H₂₄N₆O₄)	49557-75-7
GHK-Cu	The 1:1 complex of GHK with a divalent copper ion (also called copper tripeptide, copper tripeptide-1, prezatide copper).	~400.9 Da (C₁₄H₂₁CuN₆O₄)	89030-95-5
Copper peptides	A broader category of peptides that coordinate copper; GHK-Cu is the best-characterized member.	—	—

When a study, a COA, or a product page refers to “GHK-Cu,” it should be the copper-bound complex (~400.9 Da). A vial labelled “GHK” without the copper is the free tripeptide (~340.4 Da). The two are not interchangeable in an experiment that depends on the copper redox chemistry, and a mass-spectrometry result should be interpreted against the correct reference mass.

How GHK-Cu Was Discovered

The GHK sequence was first isolated in 1973 by Loren Pickart during work on factors in human plasma that affected the phenotype of aged versus young hepatocytes. Pickart identified a small tripeptide fraction from human plasma albumin that produced a marked change in the cultured cells and later identified the sequence as glycyl-histidyl-lysine. Subsequent work by Pickart and by other groups established that GHK binds Cu²⁺ with high affinity through its imidazole nitrogen, its N-terminal amine, and a deprotonated amide nitrogen, producing the GHK-Cu complex that dominates most of the biological literature on the molecule.

What the Preclinical Literature on GHK-Cu Reports

The published in-vitro and preclinical literature on GHK-Cu spans roughly five decades and has been reviewed in the peer-reviewed press by Pickart and by other groups. Reported observations include effects on extracellular-matrix protein synthesis in cultured fibroblasts, wound-healing endpoints in rodent skin models, modulation of gene-expression profiles in cell culture, and antioxidant and metal-chelation chemistry attributable to the copper coordination. It is important to describe these findings in the language the primary literature actually uses:

Collagen and extracellular-matrix expression. In fibroblast cell culture, GHK and GHK-Cu have been reported to influence expression of collagen and small proteoglycans (for example decorin) at low nanomolar concentrations, with modulation of both extracellular-matrix component levels and remodelling-related transcripts. These are cell-culture and animal-model observations, not human clinical trial endpoints.
Wound-healing models. Preclinical rodent wound-healing work has reported associations between GHK-Cu application and altered wound-closure kinetics, angiogenic and infiltrative changes, and modulation of growth-factor expression. These are preclinical findings that have not, in aggregate, translated to a general regulatory approval for wound care.
Gene-expression modulation. Larger transcriptome studies using cultured human fibroblasts have reported changes in expression of multiple gene groups after GHK exposure, spanning DNA-repair, cytoskeletal, and immune-modulatory categories. As with any in-vitro transcriptomic signal, the biological significance depends on the model and the concentration.
Copper coordination and antioxidant chemistry. The GHK-Cu complex “silences” a portion of the redox activity of free Cu²⁺, which is often cited as the mechanistic explanation for how GHK-Cu can deliver copper to cells without the toxicity of an equivalent free-copper concentration.

Human clinical evidence for GHK-Cu is limited relative to its preclinical footprint and is heavily concentrated in topical cosmetic use rather than in systemic pharmacology. Statements framing GHK-Cu as an established treatment for a specific human disease, or as an FDA-approved drug, are not supported by the current literature.

Is GHK-Cu FDA-Approved?

No. GHK-Cu is not an FDA-approved drug. It appears in cosmetic ingredient lists as copper tripeptide-1 and is regulated as a cosmetic ingredient in that context, not as a drug. A GHK-Cu research vial sold under For Research Use Only labelling is a laboratory chemical for in-vitro and preclinical work; it is not a medicine and is not intended for human use. See What Is a Research Peptide? for how RUO labelling and FDA approval relate to one another.

Research Handling of a GHK-Cu Vial

GHK-Cu is typically supplied as a lyophilized blue-tinted powder (the blue colour reflects the Cu²⁺ d-d transitions of the complex) in sealed multi-use vials. Sealed lyophilized vials are generally held at −20 °C or −80 °C; reconstituted solution is refrigerated for short-term use and aliquoted at −20 to −80 °C where the formulation allows. Actual usable life in solution depends on the peptide sequence, formulation, buffer chemistry, oxygen exposure, and freeze–thaw handling — the copper coordination adds redox considerations that a purely organic peptide does not have. The batch Certificate of Analysis is the authoritative reference for the vial in the researcher’s hand.

Two verification steps apply before use:

Read the batch Certificate of Analysis. Confirm HPLC purity, mass-spectrometric identity, appearance (a blue-tinted lyophilized powder is expected for the copper complex), water content, and endotoxin data for cell-based work. See How to Read a Peptide COA.
Match the reported mass to the expected mass. The GHK-Cu complex is close to ~400.9 Da; the free GHK tripeptide is close to ~340.4 Da. A mass that matches the free peptide on a vial labelled “GHK-Cu” means the copper is not incorporated. See How to Reconstitute Research Peptides for the benchtop protocol.

Common Misconceptions About GHK-Cu

“GHK and GHK-Cu are the same molecule.” They are not. GHK is the free tripeptide; GHK-Cu is the copper-bound complex. They have different molecular weights and different chemistry.
“GHK-Cu is an approved anti-aging drug.” It is not FDA-approved as a drug. It appears in cosmetic ingredient lists and in the preclinical literature; that is not the same as an approved indication.
“Copper peptides regrow hair.” The primary literature contains preclinical observations relating to hair-follicle biology in animal and cell models. That is different from a general clinical claim; the current evidence for a specific human hair-regrowth indication is limited.
“All GHK-Cu vials are identical.” They are not. The counterion, water content, colour, and (critically) whether the copper is actually coordinated all vary with the manufacturer. The batch COA is the arbiter, not the label.

Key Takeaways

GHK is the free tripeptide glycyl-L-histidyl-L-lysine (~340.4 Da). GHK-Cu is the 1:1 complex with Cu²⁺ (~400.9 Da). The two names refer to different chemical species.
The sequence was first isolated by Loren Pickart in 1973 from human plasma albumin; the copper complex has been the focus of most subsequent biological research.
Preclinical literature reports effects on extracellular-matrix expression, gene-expression modulation, wound-healing endpoints, and copper-associated antioxidant chemistry in cell and animal models.
GHK-Cu is not an FDA-approved drug; it appears in cosmetic ingredient lists as copper tripeptide-1.
Research verification is by batch COA: HPLC purity, mass matching the copper complex (~400.9 Da), appearance, water content, and endotoxin where relevant.

Frequently Asked Questions

What does GHK-Cu stand for?

GHK-Cu is the 1:1 complex of the tripeptide glycyl-L-histidyl-L-lysine (GHK) with a divalent copper ion (Cu²⁺). GHK is the sequence in single-letter amino-acid code (Gly-His-Lys); Cu is the coordinated copper. The complex is also called copper tripeptide, copper tripeptide-1, or prezatide copper.

What is the molecular weight of GHK and GHK-Cu?

The free GHK tripeptide has a molecular formula of C₁₄H₂₄N₆O₄ and an average molecular weight of approximately 340.4 Da. The GHK-Cu complex has a molecular formula of C₁₄H₂₁CuN₆O₄ and an average molecular weight of approximately 400.9 Da; the difference reflects the coordinated copper and the deprotonation of a coordinating nitrogen.

Who discovered GHK-Cu?

The GHK sequence was first isolated from human plasma albumin by Loren Pickart in 1973 during work on factors that changed the behaviour of aged versus young hepatocytes in culture. The copper-binding chemistry was characterized in the years that followed and became the focus of most subsequent biological research.

Is GHK-Cu the same as copper peptide?

Not exactly. “Copper peptide” is a broad term for peptides that coordinate copper. GHK-Cu is a specific copper peptide — the tripeptide GHK complexed with Cu²⁺ — and is the best-characterized member of the category. Other copper-binding peptides exist, and product pages that use “copper peptide” as a generic label may not always mean GHK-Cu specifically.

Is GHK-Cu FDA-approved?

No. GHK-Cu is not FDA-approved as a drug. It appears in cosmetic ingredient lists as copper tripeptide-1 and is regulated in that context as a cosmetic ingredient, not as a medicine. A GHK-Cu research vial is a laboratory chemical sold under For Research Use Only labelling and is not intended for human use.

How is GHK-Cu different from GHK?

GHK is the free tripeptide (Gly-His-Lys, ~340.4 Da) with no coordinated metal. GHK-Cu is the same tripeptide bound to a divalent copper ion (~400.9 Da). Much of the biological literature that is often cited as “GHK” work is really on the GHK-Cu complex, because the copper coordination is central to the redox and gene-expression observations. A vial that is labelled one way and analyzes as the other is mislabelled.

Why is GHK-Cu blue?

The blue colour comes from d-d electronic transitions of the coordinated Cu²⁺ ion in the GHK-Cu complex. Free GHK is colourless; a colourless powder on a vial labelled “GHK-Cu” is a visual signal that the copper is either absent or incompletely coordinated and warrants a look at the batch COA.

How should a GHK-Cu research vial be stored?

Sealed lyophilized GHK-Cu vials are typically held at −20 °C or −80 °C. Reconstituted GHK-Cu is refrigerated for short-term use and aliquoted at −20 to −80 °C where the formulation allows. Because the biology depends on the copper coordination, oxygen exposure and buffer chemistry deserve attention beyond what a purely organic peptide would need. The batch stability data on the COA is the authoritative reference for a specific vial.

References

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;243(124):85–7. Original isolation of the GHK sequence from human plasma. Indexed at PubMed.
Pickart L, Vasquez-Soltero JM, Margolina A. GHK Peptide as a Natural Modulator of Multiple Cellular Pathways in Skin Regeneration. Biomed Res Int 2015;2015:648108. Peer-reviewed review of GHK and GHK-Cu preclinical biology. Indexed at PubMed.
Pickart L, Margolina A. Regenerative and Protective Actions of the GHK-Cu Peptide in the Light of the New Gene Data. Int J Mol Sci 2018;19(7):1987. Review focused on the transcriptome-modulation literature. PMCID PMC6073405.
Simeon A, Wegrowski Y, Bontemps Y, Maquart FX. Expression of glycosaminoglycans and small proteoglycans in wounds: modulation by the tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu(2+). J Invest Dermatol 2000;115(6):962–8. Cell-culture and rodent wound-model characterization of GHK-Cu effects on extracellular-matrix components. Indexed at PubMed.
Chemical Entities of Biological Interest (ChEBI) / ChemicalBook. Copper tripeptide-1 (CAS 89030-95-5). Molecular formula C₁₄H₂₁CuN₆O₄, average molecular weight ~400.9.
Chemical Entities of Biological Interest (ChEBI) / ChemicalBook. GHK peptide (CAS 49557-75-7). Molecular formula C₁₄H₂₄N₆O₄, average molecular weight ~340.4.

Research use disclaimer. All peptides sold by AppealLabs are labelled FOR RESEARCH USE ONLY · NOT FOR HUMAN CONSUMPTION. Content on this page describes chemistry, discovery, and preclinical scientific literature only and is not medical advice. Nothing here should be interpreted as diagnosing, treating, curing, or preventing any disease, or as guidance for human use of GHK-Cu.