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Molecular Weight
Purity
Storage
Appearance
Solubility
01
GHK-Cu is the copper(II) complex of the tripeptide glycyl-L-histidyl-L-lysine (GHK). The free peptide was first identified in human plasma in the early 1970s and is notable for its high affinity for divalent copper, forming a stable 1:1 complex under near-neutral conditions.
Because the copper centre dominates its spectroscopic, chromatographic and mass-spectrometric behaviour, GHK-Cu is a practical model compound for metallopeptide chemistry. It is supplied here as a lyophilized reference material for in vitro work on peptide–metal coordination, speciation and analytical method development.
02
The peptide backbone is a simple three-residue sequence, Gly-His-Lys, with a free N-terminal amine and C-terminal carboxylate. Crystallographic studies show copper bound in a roughly square-planar arrangement by three nitrogen donors from a single peptide:
Glycine α-amino nitrogen
The free N-terminal amine provides the first anchoring point for the metal.
Deprotonated Gly–His amide nitrogen
Copper binding promotes loss of the amide proton, creating a strong backbone donor.
Histidine imidazole nitrogen
Completes a tridentate chelate with two fused five- and six-membered rings.
The fourth equatorial position is occupied by a carboxylate oxygen (from a neighbouring molecule in the solid state) or by solvent in solution. The lysine side-chain amine is not part of the primary chelate and remains free, which leaves it available for derivatisation or secondary interactions.
03
Research use of GHK-Cu centres on the chemistry of the complex itself rather than on attributed biological effects.
pH-dependent speciation
Potentiometric and spectroscopic titrations map the transition from free peptide and aqueous Cu(II) at low pH to the fully coordinated complex near neutral pH.
Ligand exchange
GHK-Cu is used to study copper transfer between small peptides and larger copper-binding proteins such as serum albumin under controlled in vitro conditions.
Redox behaviour
Cu(II)/Cu(I) cycling within the peptide framework is examined by cyclic voltammetry and EPR spectroscopy, including the effect of coordination on redox potential.
All characterisation described here is limited to solution chemistry and cell-free analytical systems.
04
Metallopeptide reference standard
Used as a well-defined copper–peptide standard when developing or validating methods for metal-containing peptides.
Chromatographic method development
Copper can interact with residual silanols on silica columns, so GHK-Cu is useful for testing column chemistry and mobile-phase conditions that preserve the intact complex.
Mass spectrometry calibration check
The natural ⁶³Cu/⁶⁵Cu isotope pattern provides an easy built-in check of mass accuracy and isotope modelling.
Metal-catalysed oxidation models
Employed in controlled degradation studies of how bound copper influences oxidation of co-present peptides or substrates.
05
Storage
Store the lyophilized solid at −20 °C in a sealed, desiccated container away from light. Allow the vial to reach room temperature before opening to prevent condensation.
Visual check
The blue colour reflects intact copper coordination. Fading toward colourless suggests copper loss or decomposition.
pH
Coordination weakens at acidic pH as the histidine nitrogen becomes protonated, while strongly alkaline conditions favour copper hydroxide formation. Near-neutral, mildly buffered aqueous conditions are typical for analytical work.
Incompatibilities
Strong chelators (for example EDTA) strip copper from the peptide, and reducing agents (ascorbate, DTT, TCEP) reduce Cu(II) and destabilise the complex. Avoid both unless studying the free peptide.
Solutions
Prepare solutions fresh where possible. If short-term storage is needed, aliquot and keep cold to limit repeated freeze–thaw cycles.
06
Metallopeptides need a slightly different analytical approach from ordinary peptides, because both the peptide and its metal content must be confirmed.
HPLC
Reversed-phase C18 with acidic mobile phase is standard. End-capped or low-metal columns reduce peak tailing. Note that acidic conditions can partially dissociate the complex, so the peptide peak is often assessed alongside copper content.
Mass spectrometry
ESI-MS shows the characteristic copper isotope doublet, two peaks 2 Da apart in roughly a 69:31 ratio, which distinguishes the complex from free GHK.
Copper content
The theoretical copper content of the 1:1 complex is about 15.8% by mass. Reported values on certificates are often lower because the material contains counter-ions (such as acetate) and residual water, so copper is usually confirmed by ICP or atomic absorption.
UV–visible spectroscopy
The complex shows a broad visible absorption band responsible for its blue colour; loss of this band indicates dissociation.
07
GHK is the free tripeptide glycyl-histidyl-lysine. GHK-Cu is the same peptide bound to a copper(II) ion in a 1:1 ratio. The two have different CAS numbers, molecular weights and analytical profiles.
The blue colour comes from the copper(II) centre held by the peptide. It is a useful visual indicator that the complex is intact; a colourless solution suggests copper has been lost.
15.8% is the theoretical value for the pure complex. Real material also contains counter-ions such as acetate and some residual water, which lowers the measured copper percentage.
Identity is typically confirmed by mass spectrometry, including the copper isotope pattern. Purity is assessed by HPLC, and copper content by ICP or atomic absorption.
No. It is supplied strictly as a reference compound for laboratory and analytical research and is not for human or animal use.
GHK-Cu Research Reference. (2026). Pure Peptides Labs Research Catalogue. Retrieved from https://purepeptideslabs.net/research-catalogue/copper-peptides/ghk-cu/
Materials listed on this platform are supported by independent testing and published documentation for laboratory research contexts.
