# GHK-Cu: The Copper Peptide Behind Hair and Skin Research > GHK-Cu is a copper-binding tripeptide studied for collagen synthesis, hair-follicle activity and broad gene modulation. A capsule-by-capsule digest of the copper-peptide literature, cited study by study. Each finding sorted into a clean capsule, each number tied to its study, and every honest evidence gap tagged in plain sight. The hair-follicle work leads; the collagen and gene-expression record follows. ## What GHK-Cu is, in one capsule GHK-Cu is glycyl-L-histidyl-L-lysine chelated one-to-one to a copper(II) ion, with a molecular weight of 402.92 Da and the CAS number 89030-95-5. It is the same molecule cosmetic chemists list as Copper Tripeptide-1. The GHK sequence is not synthetic in origin: it occurs inside the alpha-2 chain of type I collagen and circulates in human plasma, where Loren Pickart first isolated it in 1973 as a factor that made aged liver tissue synthesize protein like younger tissue [6]. Plasma GHK does not stay constant across a lifetime. It declines from roughly 200 ng/mL (about 10⁻⁷ M) at age 20 to roughly 80 ng/mL by age 60 [3]. That decline is the backdrop for most of the interest in the peptide: the question driving the research is whether restoring GHK locally can restore the tissue-repair signaling that falls with it. This site reads the published answer to that question one capsule at a time, with [GHK-Cu research findings](/research) sorted by tissue and every quantitative claim cited. Two distinctions run through everything below, so it is worth fixing them now. First, GHK and GHK-Cu are not interchangeable: GHK is the free tripeptide (MW 340.38, CAS 49557-75-7), and copper coordination is required for most of the documented matrix-remodeling activity, so the form a study used matters [6]. Second, the strongest evidence is topical and dermatologic; systemic and injectable claims rest on rodent and in-vitro work without validated human pharmacokinetics. Those gaps are tagged, not hidden. ## What Is a Copper Peptide? A copper peptide is a short chain of amino acids bound to a copper(II) ion, where the copper is not a contaminant but the functional core. In GHK-Cu the copper is held through the histidine imidazole nitrogen, the glycine alpha-amino nitrogen and a deprotonated amide nitrogen, leaving the lysine side chain free [6]. That coordination gives the complex a very high copper stability constant, log K around 16.4, far above the free peptide — which is what keeps the copper from circulating as a loose pro-oxidant and instead delivers it as a managed payload [6]. The copper is what does the chemistry. It enables lysyl-oxidase-mediated cross-linking of collagen and elastin, and it carries superoxide-dismutase-like antioxidant activity. Strip the copper away and the peptide loses its signature effects: free GHK does not reproduce the MMP-2 stimulation that the copper complex produces in fibroblast cultures. So when a label or a study says "copper peptide," the copper is the point, and the question to ask of any product or paper is whether the complex is intact — a detail the [copper peptide skin research](/skin-research) section returns to. ## GHK Copper Peptide: What It Is The phrase GHK copper peptide is the consumer-facing name for the exact molecule described above: the GHK tripeptide carrying its copper. It is the active behind a large share of copper-peptide serums and the subject of the dermatology and hair literature digested here. In research models it stimulates dermal fibroblasts to synthesize collagen, elastin, dermatan sulfate, chondroitin sulfate and the proteoglycan decorin, while rebalancing matrix metalloproteinases against their TIMP inhibitors toward measured remodeling rather than tissue breakdown [3][6]. The reach extends past the skin. A Connectivity Map analysis reports that GHK modulates about 31.2% of human genes at a 50%-or-greater change threshold, raising 59% of the affected genes and lowering 41%, with strong upregulation of the ubiquitin-proteasome system (41 genes up, one down) plus DNA-repair and antioxidant gene sets [2]. The often-repeated "about 4,000 genes" line is an extrapolation; the figure that the threshold table actually supports is on the order of 2,100 genes [2]. This digest uses the verified number. ## Copper Tripeptide-1 (the INCI Name for GHK-Cu) Copper Tripeptide-1 is the INCI cosmetic-ingredient name for GHK-Cu — the term you will find on a serum's ingredient list rather than in a journal. It is the same complex with the same identifiers: PubChem CID 71587328, FDA UNII 6BJQ43T1I9, DrugBank DB14683. The distinction between the lab name and the cosmetic name is purely labeling convention; the molecule is identical. The naming matters for one practical reason. Topical Copper Tripeptide-1 is a legal, widely marketed cosmetic ingredient with a long safety record, while injectable or systemic GHK-Cu is not an approved drug by any route. The cosmetic name and the research-peptide name describe the same chemistry but very different regulatory positions — a line this digest keeps visible throughout, including the [copper peptide side effects and safety](/faq) discussion. ## Where the research is strongest, and where it isn't The most replicated finding is the simplest: GHK-Cu raised collagen synthesis in human fibroblast cultures dose-dependently between 10⁻¹² and 10⁻⁹ M, peaking near 10⁻⁹ M, with no change in cell number — a specific metabolic effect, not mere proliferation (Maquart 1988) [1]. On hair, the strongest controlled human signal comes from a 6-month trial of 45 men with androgenetic alopecia, where a 5-ALA + GHK topical complex raised hair count by 52.6 and 71.5 against 9.6 for placebo — though it tested a combination, not pure GHK-Cu [4]. The honest counterweight: there is no validated human pharmacokinetic profile — no measured half-life, Cmax or bioavailability — for injectable or systemic GHK-Cu, and the dosing protocols that circulate in community settings have no peer-reviewed basis. Much of the foundational mechanistic literature also traces to a single investigator and colleagues, so independent replication of the broader gene-expression and anti-aging claims is still limited. The two leads of this digest are the [copper peptide hair growth research](/hair-research) and the [copper peptide skin research](/skin-research); the [GHK-Cu citations and references](/references) page lists every source behind them. --- The GHK-Cu copper-peptide record sorted into clean capsules — each hair, collagen and gene-expression finding paired with its source and its honest gap, with no clinic on the line and nothing here on a shelf.