Peptide Reference Desk
GHK-Cu vs AHK-Cu: two copper peptides, two evidence files
GHK-Cu and AHK-Cu are related copper-binding tripeptides, but their sequences, literature depth and product specifications are not interchangeable.
One residue changes the name—and the record
GHK-Cu is the copper complex of glycyl-histidyl-lysine. AHK-Cu uses alanine in the first position. Both sit comfortably under “copper peptides,” but that category does not give them one sequence, one expected mass or one evidence base.
Search popularity is uneven
GHK-Cu has moved into mainstream skincare searches in 2026. AHK-Cu appears more often in hair and follicle discussions, with a thinner published record. That imbalance should be stated rather than filled with claims borrowed from GHK-Cu.
| Field | Keep separate |
|---|---|
| Peptide identity | GHK sequence versus AHK sequence |
| Copper measurement | Elemental copper and peptide content |
| Complex state | Declared stoichiometry and formulation conditions |
| Evidence | Exact peptide tested, not “copper peptide” generally |
Blue is not a release test
Color can suggest a copper-containing material, but it cannot establish identity, concentration or intact complex. A useful file combines peptide identity, copper assay, chromatographic purity and formulation information.
Verify with primary records
Use the primary paper, current regulator label or lot-linked analytical file for the claim it supports. A search result is a route to evidence, not the evidence itself.