Scientifically reviewed by Dr Stephan Hansberg
GHK-Cu vs AHK-Cu: copper peptides compared (2026)
GHK-Cu and AHK-Cu are copper(II) complexes of tripeptides that differ by one amino acid. A side-by-side comparison of identity, origin, research depth and regulatory status, why they are mixed up, and which Celyfe pens contain GHK-Cu.
Key takeaways
- •GHK-Cu is copper bound to glycyl-histidyl-lysine; AHK-Cu is copper bound to alanyl-histidyl-lysine. The only difference is glycine versus alanine at position 1.
- •GHK was identified in human serum in 1973 and has a large cell and skin-model literature; AHK-Cu is a synthetic analogue with one main primary study (human hair follicles ex vivo, 2007).
- •GHK-Cu also has an INN (prezatide copper) and a cosmetic ingredient name (copper tripeptide-1); AHK-Cu has neither in the sources we checked.
- •Neither is an approved medicine. The TGA names GHK-Cu as an example of an unapproved peptide product in its 2026 compliance focus; AHK-Cu has not been named by any regulator we checked.
- •Celyfe's GLOW and KLOW pens contain GHK-Cu 75mg. No Celyfe pen contains AHK-Cu.
The short answer
GHK-Cu and AHK-Cu are both small copper peptides, and they differ by a single amino acid: GHK-Cu starts with glycine and AHK-Cu starts with alanine. GHK-Cu occurs naturally in human plasma and has been studied for five decades, while AHK-Cu is a synthetic analogue with a very small published literature.
Because the copper is bound by the same histidine and lysine region in both, they are chemically close, but research on GHK-Cu cannot be assumed to transfer to AHK-Cu.
Side by side
Identifiers checked against PubChem. Both peptides appear in PubChem both as the free tripeptide and as copper complexes, so we list the free peptide formula and the record for the copper complex separately.
| Property | GHK-Cu | AHK-Cu |
|---|---|---|
| Peptide | Gly-His-Lys (GHK) | Ala-His-Lys (AHK) |
| Other names | Prezatide copper (INN), copper tripeptide-1, Cu-GHK | Alanyl-histidyl-lysine copper |
| Free peptide formula and mass | C14H24N6O4, 340.38 g/mol | C15H26N6O4, 354.41 g/mol |
| Free peptide CAS / CID | 49557-75-7 / 73587 | 126828-32-8 / 7408502 |
| Copper complex CAS / CID | 89030-95-5 / 71587328 (prezatide copper) | 682809-81-0 / 168431292 (monohydrochloride) |
| Natural occurrence | Found in human plasma (Pickart and Thaler, 1973) | No peer-reviewed report of natural occurrence found |
| Depth of literature | Large: cell, skin and animal models, reviews | Very small: one main primary study |
| FDA | Not an approved drug; not reviewed in July 2026 | Not an approved drug; not reviewed in July 2026 |
| AU TGA | Not named in the Poisons Standard; named by the TGA as an example of an unapproved peptide product (2026) | Not named |
| WADA 2026 | Not named | Not named |
Research by model
Representative studies, with model stated. Cell and ex vivo findings do not establish effects in people.
| Peptide | Research area | Model | Example study (year, PMID) |
|---|---|---|---|
| GHK | Identification in human serum; liver cell culture | Cell | Pickart and Thaler, Nat New Biol (1973), PMID 4349963 |
| GHK | Association with copper and iron in plasma | Human plasma and cell culture | Pickart and Thaler, J Cell Physiol (1980), PMID 6246126 |
| GHK-Cu | Oxidative stress and ageing-related research overview | Review | Pickart et al., Oxid Med Cell Longev (2012), PMID 22666519 |
| GHK-Cu | Gene expression data and tissue models | Review of cell and animal work | Pickart and Margolina, Int J Mol Sci (2018), PMID 29986520 |
| AHK-Cu | Hair follicle elongation, dermal papilla cell proliferation | Human hair follicles ex vivo and cultured human cells | Pyo et al., Arch Pharm Res (2007), PMID 17703734 |
The key differences
Chemistry. Alanine carries one extra methyl group compared with glycine, so AHK is 14 Da heavier than GHK. That small change sits next to the N-terminal amine, which takes part in copper binding, so the two complexes are similar but not identical. Mass spectrometry tells them apart easily.
Evidence. GHK-Cu has decades of cell, skin and animal-model research and a body of cosmetic use. AHK-Cu's peer-reviewed evidence rests largely on Pyo and colleagues' 2007 ex vivo hair follicle and dermal papilla cell work.
Regulatory attention. GHK-Cu has drawn regulator attention because of its popularity: the TGA lists it among examples of unapproved peptide products, which it has made a compliance priority in 2026. AHK-Cu has not been named in any of the sources we checked.
Why they are commonly confused
Both are marketed as copper peptides, both are blue copper(II) complexes, and their three-letter names differ by one letter. Identifier mix-ups add to the confusion: PubChem assigns CAS 49557-75-7 to the free GHK peptide, while prezatide copper, the copper complex, has CAS 89030-95-5, and supplier listings do not always keep the two apart. A certificate for any copper peptide should say whether it reports the free peptide or the copper complex.
Telling them apart on a certificate
Because the two complexes look alike and their names differ by one letter, identity testing is what separates them. A useful certificate for a copper peptide names the peptide sequence, states whether the result refers to the free peptide or the copper complex, gives an identity result by mass spectrometry (GHK and AHK differ by 14 Da), and reports HPLC purity for the named batch. A certificate that gives only a CAS number is not enough, given how often the free-peptide and complex numbers are swapped in listings.
Which Celyfe pens contain which
GHK-Cu is in two Celyfe pens, each a pre-filled, pre-mixed 3ml cartridge shipped cold-chain and kept at 2 to 8 C. No Celyfe pen contains AHK-Cu.
| Pen | Copper peptide | Full composition | Certificate |
|---|---|---|---|
| GLOW (/products/glow-pen) | GHK-Cu 75mg | GHK-Cu 75mg + BPC-157 15mg + TB-500 15mg | Being re-issued; listed in /coa when published |
| KLOW (/products/klow-pen) | GHK-Cu 75mg | GHK-Cu 75mg + BPC-157 15mg + TB-500 15mg + KPV 15mg | Being re-issued; listed in /coa when published |
| WOLVERINE, NAD+ | None | See product pages | WOLVERINE C26071 and NAD+ A26085 published in /coa |
Sources
Primary and official sources checked October 2026:
- PubChem: Glycyl-L-histidyl-L-lysine, CID 73587; Prezatide copper, CID 71587328; Ala-His-Lys, CID 7408502; AHK-Cu, CID 168431292 (pubchem.ncbi.nlm.nih.gov)
- 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
- Pickart L, Thaler MM. Growth-modulating tripeptide (glycylhistidyllysine): association with copper and iron in plasma. J Cell Physiol, 1980. PMID 6246126
- Pickart L et al. The human tripeptide GHK-Cu in prevention of oxidative stress and degenerative conditions of aging. Oxid Med Cell Longev, 2012. PMID 22666519
- 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. PMID 29986520
- Pyo HK et al. The effect of tripeptide-copper complex on human hair growth in vitro. Arch Pharm Res, 2007. PMID 17703734
- TGA safety alert: Understanding your responsibilities when importing, compounding and supplying unapproved peptide products, April 2026 (tga.gov.au)
- Therapeutic Goods (Poisons Standard, October 2026) Instrument 2026, F2026L01327 (legislation.gov.au)
- WADA: Prohibited List 2026, in force 1 January 2026 (wada-ama.org)
Research use only
Celyfe supplies research peptides for laboratory and research use only. Nothing on this page is guidance on use in humans or animals.
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