GHK-Cu: Copper Tripeptide Identity, Matrix Research and What the Literature Covers

Evidence at a glance

Cell culture and topical human studies

GHK-Cu has a large in vitro literature and topical human skin studies behind it. Injected use has not been studied in controlled trials.

Why researchers are interested

It is a copper carrier. Copper is required by the enzymes that cross link collagen and elastin, and the peptide delivers it in a form cells can take up. Levels of GHK in plasma fall sharply with age, which is the basis for the interest in replacing it.

What the research found

• More collagen and elastinStimulated production in fibroblast cultures, including MMP-2 expression
• Better skin appearanceTopical studies reported improvements in firmness and in the appearance of fine lines
• Wound healing in animalsFaster healing and tissue remodelling in animal models (Pickart, 2008)
• Broad gene expression effectsShifted expression across a wide set of repair related genes (Pickart, 2014)

Reported in the literature

• Topical cosmetic studies report good tolerability, with irritation the main effect noted.
• No controlled safety data exists for injected use. The evidence base is topical and in vitro.
• It is a copper complex, so systemic exposure raises a copper load question that the published work does not answer.

Findings are summarised from the sources listed under References on this page, and from approved product labelling where a compound has one. These are outcomes observed in published studies, not effects claimed for any person, and nothing here is a recommendation for human use.

← All research guides

GHK-Cu is the copper(II) complex of the tripeptide glycyl-L-histidyl-L-lysine, studied in tissue-remodeling, matrix-biology and gene-expression research. This guide covers the identity of both the peptide and its copper complex, what the published literature examined, and how the material is handled in a laboratory. It is written for researchers and is not medical guidance.

What GHK-Cu is

GHK is a tripeptide, glycine-histidine-lysine, that occurs naturally in human plasma and whose reported plasma concentration declines with age. That observation is a large part of why its copper complex became a frequent subject of biochemical and cell-culture research.

The copper complex is the form supplied for research, and it is characteristically blue — the colour comes from the coordinated copper(II), not from any additive.

Two compounds, two CAS numbers

This is the detail most listings get wrong, including many that say GHK-Cu. The free peptide and its copper complex are different compounds with different registry numbers, formulas and masses. Both were checked against PubChem on 2 October 2026.

• GHK, the copper-free tripeptide — CAS 49557-75-7, PubChem CID 73587, C₁₄H₂₄N₆O₄, 340.38 g/mol.
• GHK-Cu, the copper(II) complex — CAS 89030-95-5, PubChem CID 71587328, C₁₄H₂₃CuN₆O₄⁺, 402.92 g/mol.

The practical consequence is a roughly 62 g/mol difference. A molar calculation run with the free-peptide mass against material that is actually the copper complex will be wrong, which is a real source of error when preparing solutions. Confirm which form a specification describes before computing concentrations.

Research-use note: GHK-Cu is a research chemical supplied strictly for laboratory research. It is not an approved drug, cosmetic, or supplement and is not for human or animal consumption. Every finding below comes from cell-culture, biochemical or animal-model work.

What the published literature covers

The GHK literature spans biochemical, cell-culture and genomic work, and a large share of it comes from one research group, which is itself worth knowing when weighing the evidence.

• Siméon et al. (Life Sciences, 2000) — reported that the GHK-Cu complex stimulates matrix metalloproteinase-2 (MMP-2) expression in fibroblast cultures. MMP-2 is an enzyme involved in remodelling the extracellular matrix, so this sits at the matrix-biology end of the literature.
• Pickart (J Biomater Sci Polym Ed, 2008) — a review of GHK and tissue remodeling, and the usual entry point to the field.
• Pickart et al. (BioMed Research International, 2014) — examined GHK in relation to broad patterns of gene expression.

The gene-expression work is the most frequently quoted and the most frequently overstated. Figures describing the proportion of human genes whose expression shifts in the presence of GHK come from analyses of expression data in specific cell systems. They describe correlations observed in those datasets; they are not a demonstration of an outcome in an organism, and they are routinely recycled online as though they were.

Mechanisms under investigation

Published work has examined GHK-Cu in relation to extracellular-matrix proteins including collagen and the matrix metalloproteinases, and as a copper-carrying ligand, since copper is a cofactor for enzymes involved in connective-tissue cross-linking. The copper is not incidental to the molecule; it is coordinated by the peptide, and the complex is what the matrix-biology studies examined.

These remain active areas of laboratory investigation rather than settled conclusions.

GHK-Cu as a blend component

GHK-Cu is the largest component by mass of the four-peptide KLOW blend, at 50 mg of the 80 mg total — 62.5% of the vial. Because it dominates the blend by mass, it is also the component whose literature is most often cited as though it applied to the blend as a whole. Strong evidence for GHK-Cu is evidence for GHK-Cu. The full breakdown is in our KLOW research guide.

Form, reconstitution and storage

GHK-Cu is supplied as a lyophilized powder, characteristically blue. Standard laboratory practice is to reconstitute with bacteriostatic water, swirl rather than shake until dissolved, and store the reconstituted solution refrigerated at 2–8 °C. The lyophilized powder is kept frozen and protected from light, and repeated freeze-thaw cycles are avoided. Our walkthrough covers the general procedure: how to reconstitute peptides.

(General lab-handling notes, not usage instructions, and no substitute for the protocol in force in the receiving laboratory.)

For research use only

All products and information referenced here are intended strictly for laboratory and scientific research use only. They are not for human or animal consumption and are not drugs, foods, supplements, cosmetics, or medical devices. Nothing here should be interpreted as medical advice, and no outcome in a person is described, implied or promised. Products are supplied against a stated purity specification.

Explore GHK-Cu and related research peptides

• GHK-Cu — specifications and stated purity
• KLOW 80 mg — the blend in which GHK-Cu is 50 mg of 80 mg
• KPV 10 mg — another KLOW component
• Full research catalog

Common questions about GHK-Cu

Why is GHK-Cu blue?

GHK-Cu is the copper(II) complex of the tripeptide glycyl-histidyl-lysine, and the copper gives the lyophilized powder its characteristic blue color.

Does GHK occur naturally?

Yes. GHK is found in human plasma, and published work reports that its levels decline with age, one reason its copper complex drew research interest.

Which blend contains GHK-Cu?

KLOW combines GHK-Cu with BPC-157, TB-500 and KPV. GHK-Cu is also sold on its own.

References

1. Siméon A, et al. The tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu2+ stimulates matrix metalloproteinase-2 expression by fibroblast cultures. Life Sci. 2000. PubMed
2. Pickart L. The human tri-peptide GHK and tissue remodeling. J Biomater Sci Polym Ed. 2008. PubMed
3. Pickart L, et al. GHK and DNA: resetting the human genome to health. Biomed Res Int. 2014. PubMed
4. Compound identity verified against the PubChem database, retrieved 2 October 2026. PubChem