GHK-Cu is the copper(II) complex of the tripeptide glycyl-L-histidyl-L-lysine — a naturally occurring human plasma peptide with an unusually high affinity for copper ions, studied for more than fifty years in extracellular matrix, wound-repair and skin biology. The copper is not an additive; it is part of the molecule's identity. A vial of GHK-Cu is distinctly blue, and the colour comes directly from the coordinated Cu(II) ion. Any material sold under this name that arrives as a white powder is the uncomplexed peptide, not the copper complex.
This page explains where GHK came from, how the copper coordination works, what mechanisms are reported for it, the research areas it appears in, and how the material is specified and handled. GHK-Cu is supplied here for laboratory and formulation research only.
GHK-Cu at a glance
| Property | Value |
|---|---|
| Peptide sequence | Gly-His-Lys (GHK) |
| Complexed form | GHK-Cu(II), 1:1 peptide-to-copper |
| CAS number | 89030-95-5 |
| Molecular formula | C14H24N6O4·Cu |
| Molecular weight | 403.93 g/mol (complex) |
| Appearance | Blue lyophilized powder; blue solution |
| Copper coordination | Histidine imidazole nitrogen, N-terminal amine, backbone amide nitrogen |
| Discovery | Identified in human plasma in the early 1970s |
| Sizes supplied | 50 mg, 100 mg, 200 mg vials; also serum, cream and scalp solution formats |
| Purity specification | ≥99% by RP-HPLC with lot-matched COA |
Origin and structure: a plasma tripeptide that carries copper
GHK was identified in the early 1970s by Loren Pickart during work on why plasma from young donors behaved differently from plasma from older donors in liver tissue culture. The active fraction resolved to a tripeptide, glycyl-histidyl-lysine, and subsequent work established that its biological behaviour depended on copper. Reported plasma concentrations decline substantially with age — commonly cited as roughly 200 ng/mL in the third decade of life falling to around 80 ng/mL by the seventh — and this observation underpins much of the ageing-related literature that followed.
The copper affinity is structural rather than incidental. Three donor atoms come together to form a square-planar-type coordination site around Cu(II): the imidazole nitrogen of the histidine side chain, the free alpha-amino group at the glycine N-terminus, and a deprotonated backbone amide nitrogen. The resulting complex is stable enough to hold copper in circulation but exchangeable enough to hand it to higher-affinity cellular acceptors such as albumin and copper chaperone proteins. That combination — high affinity plus exchangeability — is what distinguishes a copper peptide from an inert copper salt.
Practically, this means the complex and the free tripeptide are different products. Free GHK is a white powder with a molecular weight near 340 g/mol; the copper complex weighs 403.93 g/mol and is blue. They are not interchangeable in an experiment, and colour is the fastest identity check available.
How GHK-Cu is thought to work
No single receptor has been established for GHK-Cu, and the mechanisms reported in the literature operate at several levels at once.
Copper delivery and redox chemistry
The most concrete proposal is that GHK acts as a physiological copper transporter, delivering Cu(II) to cells and to copper-dependent enzymes. Copper is a cofactor for lysyl oxidase, which cross-links collagen and elastin, and for superoxide dismutase, so a delivery mechanism plausibly connects the peptide to matrix maturation and to redox handling without requiring a dedicated receptor.
Extracellular matrix signalling
In fibroblast culture, published work has reported increases in collagen, elastin, glycosaminoglycan and proteoglycan synthesis in the presence of GHK-Cu, together with modulation of matrix metalloproteinases and their tissue inhibitors. The picture drawn in this literature is of coordinated remodelling — both synthesis and controlled breakdown — rather than simple accumulation.
Gene expression
A distinct strand uses transcriptome-wide profiling. Published analyses of cultured cells exposed to GHK have reported changes across large numbers of genes, with enrichment in matrix, repair and antioxidant categories. These are broad, hypothesis-generating datasets, and the usual cautions about interpreting expression signatures from cell culture apply in full.
Hair follicle biology
Work on follicle organ culture and rodent models has examined follicle size and growth-phase behaviour, and this is the strand that connects GHK-Cu with related copper tripeptides such as AHK-Cu. The two are compared directly in GHK-Cu vs AHK-Cu.
The honest summary is that GHK-Cu has a large, old and mostly in-vitro literature, plus formulation studies in cosmetic science, and comparatively little controlled human trial evidence of the kind that would support any clinical claim.
What research has examined
Skin and matrix research (cell, ex vivo, some human formulation studies). Fibroblast collagen synthesis, dermal matrix composition, and cosmetic formulation studies measuring skin surface parameters. This is the largest applied body of work.
Wound-repair models (rodent, ex vivo). Studies have examined closure rate, angiogenesis and inflammatory cell recruitment in animal models, with a literature stretching back to the 1980s.
Hair research. Follicle culture and animal work, generally at lower volume than the skin literature.
Ageing and gene expression. The age-related decline in plasma GHK is the starting point for a body of work using expression profiling and cell senescence readouts.
Formulation science. Because copper complexes interact with common cosmetic ingredients — notably strong reducing agents and certain chelators — a practical literature exists on stability, pH windows and compatibility. This is directly relevant to anyone working with the GHK-Cu serum, cream or scalp solution formats.
Forms and sizes we supply
Raw GHK-Cu is stocked in 50 mg (USD 60), 100 mg (USD 90) and 200 mg (USD 155) lyophilized vials. These sizes are much larger than typical peptide vials for a straightforward reason: formulation and topical-model work consumes material by the tens of milligrams rather than the microgram. At 403.93 g/mol, a 100 mg vial contains roughly 248 micromoles, a very large molar quantity. Prepared formats and the full copper range sit under copper peptides, and buying checks are in our GHK-Cu buying guide.
Reconstitution and storage in a laboratory context
The arithmetic is simple and the numbers are unusually large. A 100 mg vial reconstituted with 10 mL of diluent gives 10 mg/mL, equivalently 10,000 mcg/mL, and approximately 24.8 mM. A 1% w/v formulation solution is 10 mg/mL by definition, which makes GHK-Cu one of the few peptides where stock concentrations map directly onto formulation percentages.
Three handling points are specific to the copper complex. First, the solution should be blue; loss of colour indicates loss of the complex. Second, copper(II) is redox-active, so avoid contact with strong reducing agents and with chelators that will strip copper from the peptide. Third, pH matters more than for most peptides, because the coordination site depends on a deprotonated backbone amide — strongly acidic conditions destabilise the complex. Lyophilized powder is stored at −20 °C, protected from light and moisture; solutions are refrigerated, protected from light and aliquoted so a single container is not repeatedly warmed and re-chilled. Broader guidance is in the peptide storage guide.
Purity, COA and how to read one
Each lot is purified by reversed-phase HPLC to at least 99% with a certificate matched to the vial lot number. GHK-Cu requires one check that most peptides do not: confirmation that the material actually is the copper complex. The colour is the first indicator, and the reported molecular weight is the second — 403.93 g/mol for the complex against roughly 340 g/mol for the free tripeptide. Where copper content is reported as a percentage, it can be compared with the theoretical value for a 1:1 complex. Beyond that, the standard checks apply: read the chromatogram for a single well-resolved peak rather than accepting a headline figure, confirm the lot number matches the vial, and note whether net peptide content is stated separately from gross weight. Our COA reading guide covers these in detail.
Regulatory status
GHK-Cu is used as a cosmetic ingredient in finished products in many markets, but the raw material supplied here is not an approved drug, not a dietary supplement, and not a finished cosmetic. It is research-grade material for laboratory and formulation investigation by qualified researchers, and is not intended for human or veterinary administration. Published skin and matrix findings describe cell systems, animal models and cosmetic formulation studies, and do not constitute therapeutic claims.
Related peptides and further reading
AHK-Cu is the closest structural relative in this catalogue, and the two are compared directly in the linked comparison above. For wider context, see the peptides for skin research overview, and for the history of the molecule, our long-form piece on fifty years of copper peptide research.