Copper Peptides

Copper peptides are a small and unusual category: the research subject is not a peptide alone but a metal complex, and that distinction drives everything about how the material is identified, handled and analysed. Supplied as lyophilised powder for laboratory research use only.

The free peptide and the complex are different substances

GHK is a tripeptide — glycyl-L-histidyl-L-lysine, C₁₄H₂₄N₆O₄, 340.38 g/mol, CAS 49557-75-7. GHK-Cu is that tripeptide coordinated to copper(II) — C₁₄H₂₃CuN₆O₄, about 402.92 g/mol, CAS 89030-95-5, the registry number for copper tripeptide-1.

The two CAS numbers are frequently used interchangeably in supplier listings, and they should not be: one describes an organic tripeptide and the other a coordination compound roughly 62 Da heavier. Anyone comparing certificates should check which registry number and which mass a document reports, because a certificate for the free peptide says nothing about whether copper is present or bound.

Why coordination chemistry matters analytically

The copper is held by the imidazole nitrogen of the histidine side chain, the terminal amine and a backbone nitrogen. That has consequences an ordinary peptide does not have:

• The complex has a visible absorption band, which is why GHK-Cu material is blue rather than white. Colour is therefore a crude but real indicator, and an off-colour or patchy cake is worth photographing on arrival.
• Copper complexes behave differently on a reverse-phase column than the free peptide, so a chromatogram of one is not comparable to a chromatogram of the other.
• Copper is redox active, which makes the complex more sensitive to conditions that would leave a plain tripeptide alone.
• Mass spectrometry of a metal complex shows the copper isotope pattern, which is a useful confirmation that the metal is actually present rather than assumed.

Our note on GHK-Cu and copper coordination covers this in more detail, and reading an HPLC chromatogram covers what to look for in the trace.

In this category

GHK-Cu in 50 mg and 100 mg vials. GHK-Cu is also a component of the larger multi-peptide blends — it is the 50 mg component in both GLOW and KLOW, which is worth knowing when comparing a blend’s price against a single-compound vial.

Analysis and handling

Products are third-party tested for HPLC purity; certificates are published on product pages and on the certificates of analysis page, and vials are matched to their certificate by cap and crimp colour. Because copper is redox active, storage discipline matters more here than for a plain tripeptide — see how peptides degrade.

Supplied for laboratory research use only. Not approved by the FDA; not manufactured to pharmaceutical GMP standards; not for human or veterinary use.