GHK-Cu is a copper tripeptide studied across collagen, hair-follicle, wound-healing, and gene-expression research.
One small copper-binding peptide, six research domains, every quantitative claim cited. This is a diagram of what the published literature measured — a reading of the record, with nothing sold and no clinic behind it.
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.
Open the downside ledger
The new effects and safety ledger starts with what can go wrong, then sets the reported upsides beside the cited limits.