Peptide reference
GHK-Cu
Glycyl-L-histidyl-L-lysine copper(II) · a naturally occurring copper-binding tripeptide
A three-amino-acid peptide found in human plasma that binds copper(II) with high affinity — and whose concentration falls markedly with age.
Residues
3
Complex formula
C14H22CuN6O4
Molecular weight
~403.9 g/mol
INCI name
Copper Tripeptide-1
Researched effects
GHK-Cu has more direct human data than most peptides in this category, but that data is overwhelmingly small topical cosmetic studies, not large clinical trials.
Collagen synthesis
Stimulates collagen production in dermal fibroblasts.
Elastin and glycosaminoglycans
Increased synthesis of dermal matrix components.
Decorin upregulation
A proteoglycan involved in ordered collagen fibril assembly.
Wound healing
Improved healing rates in animal wound models.
Skin appearance
Improvements in firmness, elasticity and fine lines in small cosmetic trials.
Antioxidant activity
Copper delivery to superoxide dismutase; reduction of lipid peroxidation.
Anti-inflammatory signalling
Modulation of inflammatory mediators.
Hair follicle stimulation
Increased follicle size and growth in models.
Broad gene expression modulation
Connectivity Map analysis reported GHK shifting the expression of a large number of human genes toward a healthier profile.
Sequence & coordination
Three residues, N-terminus to C-terminus, with copper(II) bound at the centre. Toggle the view to see what changes on binding.
Hover or focus a residue to inspect. Dashed lines are Cu(II) coordination bonds: to the N-terminal amine, to the imidazole nitrogen of His-2, and to the deprotonated backbone amide nitrogen between Gly-1 and His-2.
Amino acid composition
At three residues, composition is trivially even — each residue is exactly one third of the chain.
At length 3 each residue is exactly 33.3% — composition percentages are trivial here; the story is the roles.
Glycine · Structural
Free N-terminal amine donates to Cu(II).
Histidine · Aromatic
Imidazole nitrogen is the key Cu(II) anchor.
Lysine · Basic
Side-chain amine drives net positive charge and membrane affinity.
Structural properties
Four readouts characterising the tripeptide and its complex.
Readout · 01
High-affinity copper(II) binding
The defining property. GHK binds Cu(II) tightly enough to exchange copper with albumin in plasma.
Readout · 02
Net charge ≈ +2 (free peptide)
No acidic residues. The N-terminal amine and lysine side chain both carry positive charge at physiological pH.
Readout · 03
No cysteine, no proline
No disulphide bonds and no proline-driven backbone rigidity — a simple, small, flexible chain.
Readout · 04
Very small
3 residues, ~340 Da free / ~404 Da complexed — far smaller than typical bioactive peptides, central to topical formulation use.
Plasma decline with age
Widely cited figures from the foundational literature — population estimates, not a diagnostic reference range.
Plasma GHK falls from ~200 ng/mL around age 20 to ~80 ng/mL by age 60.
Proposed mechanisms
Pathways inferred from in vitro and animal work. Proposed rather than confirmed in humans.
Regulatory status
Established cosmetic ingredient.
Copper Tripeptide-1 is a recognised cosmetic ingredient used in topical skincare in the US, UK and EU.
Not an approved medicine.
No marketing authorisation as a drug; injectable use is not an approved route and is not a licensed medicinal use.
Evidence quality.
Topical human evidence exists but comes largely from small, industry-adjacent cosmetic studies. Systemic and injectable use is not supported by comparable data.