What is GHK-Cu's molecular weight?

402.92 Da for the copper complex, 340.38 Da for the free peptide. Sources frequently quote the free peptide's mass while labelling it as the complex.

Is GHK the same as GHK-Cu?

No. GHK is the free tripeptide; GHK-Cu is that peptide with copper(II) bound, displacing a proton. They differ by 62.54 Da.

Loren Pickart, in 1973, from the albumin fraction of human plasma while studying why young plasma altered protein synthesis in older liver tissue.

What Is GHK-Cu? The Glycyl-Histidyl-Lysine Copper Complex

The short answer

GHK-Cu is a copper(II) complex of the tripeptide glycyl-L-histidyl-L-lysine, first isolated from human plasma albumin fraction by Loren Pickart in 1973. The free peptide has a molecular weight of 340.38 Da; the copper complex is 402.92 Da, the difference being copper bound in place of a displaced proton.

Key facts

Peptide sequence: Gly-His-Lys (GHK)
Free peptide MW: 340.38 Da (C14H24N6O4)
Copper complex MW: 402.92 Da (C14H23CuN6O4+)
GHK CAS: 49557-75-7
GHK-Cu CAS: 89030-95-5
PubChem CID (GHK): 73587
PubChem CID (GHK-Cu): 71587328
Isolated: 1973, human plasma albumin fraction

Two molecules, one name

GHK and GHK-Cu are routinely used interchangeably and they are not the same substance. GHK is the free tripeptide glycyl-histidyl-lysine at 340.38 Da. GHK-Cu is that peptide with a copper(II) ion bound, at 402.92 Da. The 62.54 Da difference is copper's atomic mass minus one proton, because binding displaces a hydrogen. Which one a paper studied matters, and the two are not always distinguished carefully in secondary writing.

Where it came from

Loren Pickart isolated the peptide from the albumin fraction of human plasma in 1973, in the course of work on a different question: why plasma from young donors, added to liver tissue from older donors, caused that tissue to synthesise proteins in a pattern more characteristic of younger tissue. The active fraction turned out to be a tripeptide. It carried the working name liver cell growth factor for a period, and is also indexed as prezatide.

Research material referenced

GHK-Cu 100mg, third-party HPLC tested

Buy GHK-Cu · £24.99

Why the copper matters

The histidine imidazole and the terminal amine give GHK a binding site with high affinity for copper(II), and the peptide is generally described as functioning as a copper carrier rather than as a peptide acting alone. That framing has a consequence often missed: much of the reported activity is attributed to delivering copper to enzymes that need it, which makes GHK-Cu as much a metal-delivery system as a signalling peptide.

What the literature reports

Published work describes effects on extracellular matrix biosynthesis, wound-repair models, antioxidant activity via copper delivery, and broad modulation of gene expression. Pickart and Margolina reported in BioMed Research International in 2015 that GHK modulates expression of more than 4,000 human genes, using the Broad Institute Connectivity Map. Nearly all of this is in vitro or animal work.

The declining-with-age observation

Plasma GHK concentrations are reported to fall with age, which is the observation the compound's anti-ageing framing rests on. It is a correlation in an observational measurement, and it does not establish that restoring the concentration reverses anything. A distinction that most writing about GHK-Cu does not make.

Regulatory position

GHK-Cu holds no marketing authorisation from the MHRA, EMA or FDA as a medicine. Copper tripeptide-1 is a recognised cosmetic ingredient name, which means topical products containing it are regulated as cosmetics. A different framework entirely from medicines, and not a route by which research material becomes a licensed product. Material supplied here is for laboratory research only.

Frequently asked questions

What is GHK-Cu's molecular weight?: 402.92 Da for the copper complex, 340.38 Da for the free peptide. Sources frequently quote the free peptide's mass while labelling it as the complex.
Is GHK the same as GHK-Cu?: No. GHK is the free tripeptide; GHK-Cu is that peptide with copper(II) bound, displacing a proton. They differ by 62.54 Da.
Who discovered it?: Loren Pickart, in 1973, from the albumin fraction of human plasma while studying why young plasma altered protein synthesis in older liver tissue.

Extended research context

The GHK-Cu (Copper Peptide) deep dive

Deep dive: why the copper ion matters

The GHK tripeptide (Gly-His-Lys) coordinates a Cu²⁺ ion through the imidazole nitrogen of histidine, the terminal α-amino group of glycine, and a deprotonated peptide-bond nitrogen. This near-square-planar geometry is what gives the complex its characteristic deep-blue colour and its redox-modulating chemistry. Uncomplexed GHK is a different molecule pharmacologically. Nearly every peer-reviewed study attributes activity to the copper-bound form, which is why suppliers ship the pre-complexed GHK-Cu rather than plain GHK.

GHK-Cu in the transcriptomic literature

The most-cited modern papers on GHK-Cu come from the Pickart & Margolina group and independent transcriptomic re-analyses. GHK-Cu has been reported to modulate expression of >4,000 human genes at nanomolar concentrations in Broad Institute Connectivity Map re-analyses, including genes involved in DNA repair, antioxidant defence, and ECM remodelling. This gene-signature-level activity is the reason GHK-Cu appears in so many research reviews outside of dermatology.

Analytical fingerprinting of GHK-Cu

On reverse-phase HPLC, GHK-Cu elutes as a well-defined peak; free GHK and copper-free peptide impurities are distinguishable. UV-Vis at ~520 nm confirms the copper d-d transition band. Reputable suppliers publish both HPLC (≥98% area) and mass-spec identity (~340 Da complex, 340.4 free peptide) on the batch CoA.

Research applications

▸In vitro fibroblast and keratinocyte gene-expression studies
▸ECM turnover assays (collagen, elastin, decorin, MMP profiling)
▸Wound-healing scratch assays in cell culture models
▸Antioxidant-mechanism studies (copper redox modulation)
▸Formulation R&D: cosmetic and topical carrier compatibility research

Handling checklist

✓Store lyophilised vial at 2–8 °C, protected from light
✓Reconstitute with bacteriostatic or sterile water; expect a blue-tinted solution
✓Avoid contact with reducing agents (ascorbic acid destabilises Cu²⁺)
✓Aliquot reconstituted solution for freeze/thaw minimisation
✓Verify blue colour and CoA HPLC ≥98% before use

Common research-handling mistakes

Learnt from thousands of researcher orders across our UK labs.

✗ Buying GHK without copper

Fix: Confirm the CoA reads GHK-Cu (copper-bound); free GHK is a different pharmacology.

✗ Mixing with vitamin C in solution

Fix: Ascorbate reduces Cu²⁺ to Cu⁺ and destabilises the complex, keep them separate.

✗ Exposing to sunlight

Fix: Store in amber vial or foil-wrapped container at 2–8 °C.

Continue researching

Peer-reviewed guides, comparators and matched reference materials.

Primary sources & clinical trials

Peer-reviewed research and registered trials from PubMed, ClinicalTrials.gov, PubChem, FDA and NIH. All links open in a new tab and point to the primary source, so every claim can be verified at origin.

UKP

Written and reviewed by

The UK Peptides Editorial Team · Research library, UK Peptides

The editorial team is responsible for supplier selection, batch release decisions and the content published in this research library. Every article here is sourced to primary literature and every product page to a signed third-party certificate. Corrections are made in place and the review date updated.

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What Is GHK-Cu? The Copper Complex Isolated in 1973