GHK-Cu is a copper tripeptide studied across collagen, hair-follicle, wound-healing, and gene-expression research.

What the GHK-Cu literature partitions into

GHK-Cu is the glycyl-L-histidyl-L-lysine copper(II) complex — three amino acids carrying a single copper ion, with a molecular weight of 402.92 Da ^[3]. It was first isolated from human plasma by Loren Pickart in 1973 as a factor that made aged liver tissue synthesize proteins like younger tissue ^[3]. Read across forty years of publications, its reported activity does not scatter; it segments cleanly into a handful of research domains, which is why this site reads it as a diagram.

The largest slice is gene expression. Connectivity Map analyses report that GHK modulates expression of roughly 31.2% of human genes at a 50%-or-greater change threshold — 59% of those upward, 41% downward — with strong activation of the ubiquitin-proteasome, DNA-repair, and antioxidant programs ^[2]; the full GHK-Cu gene-expression findings sit on the mechanism page. The skin slice is the oldest and most directly measured: in human fibroblast cultures GHK-Cu stimulated collagen synthesis beginning between 10⁻¹² and 10⁻¹¹ M, peaking near 10⁻⁹ M, with no change in cell number ^[1]. The hair-follicle slice carries the strongest controlled human signal, a 45-patient trial in which a GHK-containing topical out-grew placebo over six months ^[4]. The remaining slices — wound-healing and angiogenesis, antioxidant and redox chemistry, and safety and regulatory status — round out the ring.

What unifies them is the copper. The matrix-remodeling activity is copper-dependent: the free GHK tripeptide does not reproduce GHK-Cu's stimulation of MMP-2 in fibroblast cultures, so the chelate, not the peptide alone, carries the effect ^[7]. That distinction — GHK vs GHK-Cu — is the thread that runs through every domain below, and the one most often blurred in popular write-ups.

GHK Copper Peptide: What the Tripeptide-Copper Complex Is

GHK copper peptide is the copper-bound form of the tripeptide glycine-histidine-lysine. The copper(II) ion is held in a 1:1 complex coordinated through the histidine imidazole nitrogen, the glycine α-amino nitrogen, and the deprotonated glycine-histidine amide nitrogen, leaving the lysine side chain free ^[6]. The GHK sequence is not synthetic in origin — it occurs endogenously inside the α-2(I) chain of type I collagen and in the matricellular protein SPARC/osteonectin, and proteolysis of SPARC releases GHK-family copper-binding peptides that stimulate angiogenesis ^[8].

The complex is strikingly stable. Its copper stability constant is on the order of log K ≈ 16.4 — far higher than free GHK — which limits the release of pro-oxidant free copper and keeps the chelate intact in solution ^[6]. The expected blue-violet color of a reconstituted GHK-Cu solution is the copper(II) d-orbital absorption signature of an intact complex; a brown or green shift indicates oxidation or precipitation ^[6]. This is the molecule that the rest of this site's research domains are built around.

Copper Peptides as a Research Class

Copper peptides are short peptides that chelate copper(II) and, in doing so, gain biological activity the bare peptide does not have. GHK-Cu is the most-studied member, but it is one of a small family: KGHK, a longer SPARC-derived fragment, is actually the more potent angiogenic peptide of the group in endothelial assays ^[8], and AHK-Cu, the alanyl analog, has been tested in hair-follicle models as a close structural cousin ^[13].

What defines the class is copper-dependence. The metal is not a passenger — in GHK-Cu it enables lysyl-oxidase-mediated collagen and elastin cross-linking and a superoxide-dismutase-like antioxidant chemistry, and the matrix-remodeling signal requires the copper-bound form to appear at all ^[7]. Positioning GHK-Cu within this class matters because much of the popular literature on "copper peptide" generalizes from GHK-Cu's data to copper peptides broadly, when the controlled evidence is mostly GHK-Cu-specific.

Copper Tripeptide-1 (the INCI name for GHK-Cu)

Copper Tripeptide-1 is the INCI cosmetic-ingredient name for GHK-Cu — the label term you see on skincare ingredient lists for copper-peptide content. The two names refer to the same molecule: CAS 89030-95-5, molecular formula C₁₄H₂₃CuN₆O₄⁺ ^[3]. Other synonyms in the literature include copper tripeptide-1, prezatide copper, and glycyl-histidyl-lysine copper. The INCI designation is the regulatory hinge for this compound: topical Copper Tripeptide-1 is a legal cosmetic ingredient with a long marketed record, while injectable or systemic GHK-Cu is unapproved and research-only ^[3]. The same three amino acids and the same copper ion sit behind both labels.

What Is Copper Peptide? A Working Definition

What is copper peptide, defined plainly: it is a peptide complexed to a copper(II) ion that thereby acts as both a copper chaperone — shuttling the metal to copper-dependent enzymes — and a signaling molecule in its own right. In the case of GHK-Cu, the peptide is a tripeptide of exactly three amino acids (glycine, histidine, lysine), and the complex stimulates dermal fibroblast synthesis of collagen, elastin, glycosaminoglycans, and the proteoglycan decorin at nanomolar concentrations ^[3]. The "copper" half is doing real chemistry: copper coordination is what enables most of the documented tissue-repair activity, which is why the free peptide and the copper complex are not interchangeable ^[7]. The full account of how GHK-Cu works follows the same copper-dependent logic.

What the Research Reports as Copper Peptide Benefits

The documented research outcomes for copper peptides cluster around matrix synthesis, angiogenesis, and wound closure — framed throughout this site as study findings in models, not as benefits promised to people. The foundational tissue-remodeling review reports that GHK-Cu increases protein synthesis of collagen, elastin, metalloproteinases, anti-proteases, VEGF, FGF-2, NGF, and the neurotrophins, while suppressing free radicals, thromboxane, TGF-β1, TNF-α, and protein glycation, and chemoattracting repair cells such as macrophages and capillary cells ^[6].

In skin specifically, a reviewed clinical figure reports topical GHK-Cu raised collagen production in 70% of treated women, versus 50% for vitamin C and 40% for retinoic acid ^[3]. In hair, a six-month controlled trial recorded a hair-count gain of up to +71.5 versus +9.6 for placebo ^[4]. These are the strongest documented copper-peptide benefits in the peer-reviewed record — and each is anchored to a specific study rather than to category folklore. The honest counterweights — the in-vitro-vs-human gap, the single-investigator concentration of much of the gene-expression literature, and the absence of systemic pharmacokinetic data — are laid out on the research page and in the FAQ.