Research area

Copper peptides

Copper peptides are short peptides that bind copper(II) through a histidine imidazole and neighbouring nitrogens, forming blue complexes; GHK-Cu and AHK-Cu are the two listed by Vesta.

GHK (glycyl-histidyl-lysine) is a naturally occurring tripeptide with a high affinity for copper(II). Its copper complex has been studied for its coordination chemistry, including crystallographic work that uses the copper-binding tripeptide as a phasing tag, and for its use in skin biology and cosmetic-science research. AHK-Cu, in which alanine replaces glycine, has a much smaller literature.

Because the active species is a metal complex, a copper peptide is more than a peptide: the stoichiometry, the oxidation state of copper and the counter-ion all matter to the result of an experiment.

Compounds in this group

Compound	Type	Formula	Average mass (g/mol)	Listings
AHK-Cu	Peptide-copper(II) complex	C₁₅H₂₆N₆O₄	354.40	2
GHK-Cu	Peptide-copper(II) complex	C₁₄H₂₄N₆O₄	340.38	4

Analytical points for this group

Ask for a copper assay (for example ICP or colorimetry) in addition to HPLC purity; the peptide mass alone does not show how much copper is bound.
In mass spectrometry the complex shows a doublet pattern from the copper isotopes 63Cu and 65Cu.
The molecular weight on a COA depends on the form (free acid, acetate, hydrochloride) and on whether copper is present at a 1:1 ratio.
Copper(II) peptide solutions are typically blue; an unusual colour can indicate a different species.

Guides

ExplainerPeptide Counter-Ions and Net Peptide Content: Why the Powder Weighs More Than the Peptide

TFA and acetate counter-ions, bound water and net peptide content explained, with a worked example of how a 1000 Da peptide becomes a 1228 Da salt.

ExplainerPeptide Purity vs Vial Content: Why the Numbers Differ

Why a high HPLC area percentage does not establish peptide quantity, net vial mass, identity, water content, or counterion content.

GuideHow to Read a Peptide Certificate of Analysis (COA)

A practical laboratory checklist for reviewing peptide identity, purity, content, batch details, methods, and third-party verification on a COA.

Frequently asked questions

Which compounds are in the copper peptides group?

AHK-Cu, GHK-Cu.

How should a batch of a copper peptides compound be checked?

Ask for a copper assay (for example ICP or colorimetry) in addition to HPLC purity; the peptide mass alone does not show how much copper is bound. In mass spectrometry the complex shows a doublet pattern from the copper isotopes 63Cu and 65Cu.

Other research areas

All compound references →