GHK-Cu Reference: Copper Tripeptide-1 Chemistry, CAS and Handling

GHK-Cu is the copper(II) complex of the tripeptide glycyl-L-histidyl-L-lysine — a three-amino-acid sequence (Gly-His-Lys) that binds a single copper ion. It is one of the most studied short peptides in dermatological and matrix-biology research. This page is a chemistry and handling reference for the compound.

Identity and physical data

A note on the CAS number

This is worth flagging because it is frequently reported incorrectly. 49557-75-7 is the CAS registry number for the GHK tripeptide itself. The copper complex, GHK-Cu, has its own registry number: 89030-95-5. Many product listings use 49557-75-7 for the complex. If a Certificate of Analysis for a copper-complexed product cites only 49557-75-7, that is a documentation inconsistency worth asking about — the two are chemically distinct species with different molecular weights.

Why the material is blue

The colour is diagnostic. Free GHK is a white to off-white powder. The copper(II) complex is blue, and the intensity of the blue reflects the copper coordination. A product sold as GHK-Cu that arrives as a white powder is either not complexed or is complexed at a much lower ratio than labelled. This is one of the few visual quality checks available on a lyophilized peptide.

Coordination chemistry

In the complex, the copper(II) ion is coordinated by the imidazole nitrogen of the histidine residue, the terminal amino nitrogen of glycine and the deprotonated amide nitrogen of the glycyl-histidyl bond, with additional coordination from the lysine side. The resulting geometry is described as square-pyramidal.

The practical significance of the complexation is that bound copper is redox-silenced relative to free copper ions — the coordination environment stabilises the metal centre. This is why the complex, rather than a copper salt plus peptide mixture, is the form used in research.

Handling and storage

• Dry powder: store at −20 °C, sealed, protected from light and moisture. Stable long-term under these conditions.
• Before opening: allow the vial to reach room temperature so condensation does not form on cold powder.
• Reconstitution: bacteriostatic water is the standard solvent. See the reconstitution guide.
• In solution: refrigerate, protect from light, avoid repeated freeze-thaw cycles. Copper complexes are sensitive to strong reducing agents and to chelators such as EDTA, which will strip the metal from the peptide.
• pH: the complex is most stable near neutral to slightly alkaline pH. Strongly acidic conditions favour dissociation.

Research context

GHK was first isolated from human plasma and is present in plasma, saliva and urine. Reported plasma concentrations decline with age, from roughly 200 ng/mL around age 20 to roughly 80 ng/mL by age 60. The peptide has been studied extensively in extracellular-matrix biology and in dermatological research, and Copper Tripeptide-1 appears as an INCI-listed ingredient in cosmetic formulation. Research literature on the compound spans several decades and is available through PubMed.

What to check on the Certificate of Analysis

• HPLC chromatographic purity with the detection wavelength stated
• Mass spectrometry confirming the observed mass against the theoretical value
• Batch or lot identifier matching the vial label
• Whether the CAS number cited corresponds to the complex or the free peptide

Reading guide: how to read a peptide COA and what 99% purity means.

Availability

GHK-Cu 100 mg is supplied as lyophilized powder in a sealed vial with batch documentation on the product page. Bacteriostatic water is sold separately. Related short peptides in the catalog include SNAP-8 (Acetyl Octapeptide-3) and KPV.

Intended for laboratory and research use only. Not a medicine. Not for human or veterinary use, and not for diagnostic or therapeutic application.