GHK is the free glycine-histidine-lysine tripeptide with inherent copper-chelating capacity; GHK-Cu is its copper(II) complex, which is the biologically active form responsible for most published wound-healing, antioxidant, and gene-regulatory effects.
Research reference only — all information on this page summarises peer-reviewed scientific literature and does not constitute medical advice. View full compound profiles: GHK · GHK-Cu
Mechanism Comparison
GHK (Gly-His-Lys) is an endogenous tripeptide first isolated from human plasma by Loren Pickart in 1973. Its histidine imidazole and glycine amine groups form a high-affinity copper(II) chelation site. In biological contexts, GHK circulates primarily as GHK-Cu, its copper-bound complex, and plasma GHK-Cu levels decline significantly with age — from approximately 200 ng/mL at age 20 to below 80 ng/mL after age 60. GHK-Cu has been shown to modulate over 4,000 human genes in microarray studies (Pickart & Margolina, 2018), upregulating wound-repair genes (COL1A1, TGF-β1, VEGF) and downregulating inflammatory and oncogenic pathways. The copper cofactor is not merely a structural addition — it is mechanistically essential. Studies comparing GHK to GHK-Cu have demonstrated that the copper-bound form produces significantly greater fibroblast activation, collagen synthesis stimulation, and tissue contraction than the free peptide. However, GHK alone retains some biological activity, including copper transport and modest pro-healing effects, particularly at high concentrations.
Side-by-Side Attributes
| Attribute | GHK | GHK-Cu |
|---|---|---|
| Structure | Free tripeptide: Gly-His-Lys | Copper(II) complex of GHK: GHK + Cu²⁺ |
| Copper dependency | Copper-free; functions as copper chelator and carrier | Copper-bound; copper cofactor is mechanistically active |
| Biological potency | Lower in most wound-healing assays; retains copper-delivery and modest gene activity | Higher in fibroblast activation, collagen synthesis, and VEGF upregulation |
| Gene regulatory scope | Limited published data on free GHK gene effects | Modulates >4,000 human genes in microarray studies; broad regenerative profile |
| Research applications | Copper transport studies, baseline comparison control | Wound healing, skin aging, hair growth, antioxidant, anti-inflammatory, gene modulation |
| Common research format | Free acid or acetate salt | Copper(II) chelate (blue/green solution) |
| Cosmetic use | Uncommon | Widely used in cosmetic serums and wound-care preparations |
| Regulatory status | Research compound; not FDA-approved | Research compound; not FDA-approved; cosmetic ingredient (not drug use) |
Key Research Points
- 1GHK is a copper-chelating tripeptide with inherent but modest biological activity; GHK-Cu is the physiologically relevant copper-bound form responsible for the majority of published tissue-repair and gene-regulatory effects.
- 2Plasma GHK-Cu levels decline with age (from ~200 ng/mL at age 20 to <80 ng/mL after age 60), supporting interest in its role in age-associated decline in tissue repair capacity.
- 3GHK-Cu has been shown to modulate over 4,000 human genes in microarray analysis, including upregulation of collagen synthesis, VEGF, and wound-repair genes, and downregulation of inflammatory and oncogenic pathways.
- 4The copper cofactor in GHK-Cu is not a passive structural component — it is mechanistically required for full fibroblast activation and most published biological effects; GHK alone does not replicate the potency of the complex.
- 5GHK-Cu is widely used as a cosmetic ingredient (not subject to FDA drug approval requirements in that context), giving it a much larger commercially available research supply than most research peptides.
Frequently Asked Questions
What is the difference between GHK and GHK-Cu?
GHK is the free tripeptide (glycine-histidine-lysine) with high affinity for copper(II) ions but without copper bound. GHK-Cu is its physiologically active copper(II) complex. Most published biological effects — collagen synthesis, VEGF upregulation, wound healing, and gene regulatory activity — have been demonstrated with the copper-bound form. GHK alone retains copper-transport function and some biological activity, but at substantially lower potency in direct comparisons.
Does GHK-Cu need copper supplementation to work?
No additional copper supplementation is typically used in GHK-Cu research. GHK-Cu arrives as a pre-formed copper(II) complex; the copper is already incorporated. Studies examining GHK-Cu's activity do not require exogenous copper co-administration. The distinction matters primarily when using free GHK (without copper), where the biological effect depends on whether sufficient endogenous copper is available for complexation.
Is GHK-Cu safe for topical cosmetic use?
GHK-Cu has an extensive cosmetic safety record as a topical ingredient and is listed in the International Nomenclature of Cosmetic Ingredients (INCI) as "Copper Tripeptide-1." Topical cosmetic use does not constitute medical or therapeutic use and is evaluated under cosmetic safety frameworks, not FDA drug approval requirements. Research on systemic administration (subcutaneous or intravenous) is more limited, and no systemic therapeutic indication has received regulatory approval.
Full compound profile
GHK
Full compound profile
GHK-Cu