The difference in one sentence
Both are tripeptides that bind copper. GHK-Cu begins with glycine, AHK-Cu with alanine. That single amino acid is the entire structural distinction.
Composition
GHK-Cu is glycyl-L-histidyl-L-lysine complexed with copper(II). The GHK sequence occurs naturally in human plasma, and its concentration declines with age — which accounts for much of the scientific interest.
AHK-Cu is alanyl-L-histidyl-L-lysine, likewise complexed with copper. The histidine and lysine positions are identical to GHK; only the first residue differs.
| Feature | GHK-Cu | AHK-Cu |
|---|---|---|
| Sequence | Glycyl-histidyl-lysine | Alanyl-histidyl-lysine |
| First residue | Glycine | Alanine |
| Occurrence | Naturally present in human plasma | Synthetic analogue |
| Research focus | Skin matrix, collagen (in vitro) | Hair follicle cells (in vitro) |
Why that one position matters
In a tripeptide, one residue is a third of the molecule. The histidine imidazole ring is the principal copper-binding site in both, but the first position influences the spatial orientation of the complex and therefore how it behaves in solution.
The practical consequence: despite near-identical formulas, the literature treats them within separate research lines rather than as interchangeable.
What the research addresses
Research into GHK-Cu is the more extensive of the two and concentrates on skin matrix and collagen synthesis in in-vitro models.
Research into AHK-Cu is smaller in volume and is more often described in the context of hair follicle cells. Both literatures are preclinical.
What this article does not cover
No statements about efficacy, cosmetic outcomes, dosing or which is superior. Our copper peptides are supplied strictly for laboratory research.
Further
See GHK-Cu · Knowledge base · reconstitutie
For in-vitro laboratory research only. Not for human consumption. Not cosmetic or medical advice.
Last updated: August 2026