Does lysine bind the copper?

No. Coordination comes from the N-terminal amine, a backbone nitrogen and the histidine imidazole. Lysine contributes charge and solubility.

Would any His-containing tripeptide bind copper this way?

No. The site depends on the specific spacing between the N-terminal amine and the histidine, which this sequence provides.

Is complex formation pH-dependent?

Yes, because a backbone amide proton must be displaced for binding, and that deprotonation is pH-sensitive.

GHK Copper Peptide Molecular Structure

The short answer

GHK is a linear tripeptide: glycine, histidine, lysine, joined by two peptide bonds. Its N-terminal amine, the first backbone nitrogen and the histidine imidazole form a three-nitrogen copper-binding site, with lysine contributing charge but not coordination.

Key facts

Peptide bonds: Two
Free GHK formula: C14H24N6O4
Complex formula: C14H23CuN6O4+
Coordinating residues: Glycine (amine), histidine (imidazole)
Non-coordinating: Lysine side chain
Geometry: Square-planar Cu(II)

Why the order of residues matters

The copper-binding site depends on glycine being N-terminal and histidine sitting at position three. That spacing places three nitrogen donors at the right distances to coordinate a single metal ion. Rearranging the same three residues would not produce the same site, which is why GHK is specifically this sequence and not any tripeptide containing histidine.

What each residue contributes

Glycine provides the free N-terminal amine and, having no side chain, imposes no steric obstruction on the binding site. Histidine provides the imidazole nitrogen, the strongest donor in the set. Lysine contributes a positively charged side chain that affects solubility and how the molecule interacts with negatively charged surfaces, but takes no part in coordinating copper.

Research material referenced

GHK-Cu 100mg, third-party HPLC tested

Buy GHK-Cu · £24.99

The geometry

Copper(II) favours square-planar coordination. Three nitrogens from the peptide occupy three positions and a fourth is available to solvent or another donor. That arrangement is stable and well defined, which is what makes the complex a discrete chemical species with its own CAS number rather than a loose association.

The proton that leaves

One backbone amide nitrogen must be deprotonated to act as a donor. That is why the complex weighs 62.54 Da more than free GHK rather than the 63.55 of a copper atom, and it means complex formation is pH-sensitive: the deprotonation has to be energetically accessible.

Size, in context

At three residues GHK is among the smallest bioactive peptides in common research use, smaller than Selank at seven, MOTS-c at sixteen, and vastly smaller than the incretin analogues at around forty. That compactness is part of why its chemistry is so well defined: there is very little molecule to do anything unexpected.

Frequently asked questions

Does lysine bind the copper?: No. Coordination comes from the N-terminal amine, a backbone nitrogen and the histidine imidazole. Lysine contributes charge and solubility.
Would any His-containing tripeptide bind copper this way?: No. The site depends on the specific spacing between the N-terminal amine and the histidine, which this sequence provides.
Is complex formation pH-dependent?: Yes, because a backbone amide proton must be displaced for binding, and that deprotonation is pH-sensitive.

Extended research context

The GHK-Cu (Copper Peptide) deep dive

Deep dive: why the copper ion matters

The GHK tripeptide (Gly-His-Lys) coordinates a Cu²⁺ ion through the imidazole nitrogen of histidine, the terminal α-amino group of glycine, and a deprotonated peptide-bond nitrogen. This near-square-planar geometry is what gives the complex its characteristic deep-blue colour and its redox-modulating chemistry. Uncomplexed GHK is a different molecule pharmacologically. Nearly every peer-reviewed study attributes activity to the copper-bound form, which is why suppliers ship the pre-complexed GHK-Cu rather than plain GHK.

GHK-Cu in the transcriptomic literature

The most-cited modern papers on GHK-Cu come from the Pickart & Margolina group and independent transcriptomic re-analyses. GHK-Cu has been reported to modulate expression of >4,000 human genes at nanomolar concentrations in Broad Institute Connectivity Map re-analyses, including genes involved in DNA repair, antioxidant defence, and ECM remodelling. This gene-signature-level activity is the reason GHK-Cu appears in so many research reviews outside of dermatology.

Analytical fingerprinting of GHK-Cu

On reverse-phase HPLC, GHK-Cu elutes as a well-defined peak; free GHK and copper-free peptide impurities are distinguishable. UV-Vis at ~520 nm confirms the copper d-d transition band. Reputable suppliers publish both HPLC (≥98% area) and mass-spec identity (~340 Da complex, 340.4 free peptide) on the batch CoA.

Research applications

▸In vitro fibroblast and keratinocyte gene-expression studies
▸ECM turnover assays (collagen, elastin, decorin, MMP profiling)
▸Wound-healing scratch assays in cell culture models
▸Antioxidant-mechanism studies (copper redox modulation)
▸Formulation R&D: cosmetic and topical carrier compatibility research

Handling checklist

✓Store lyophilised vial at 2–8 °C, protected from light
✓Reconstitute with bacteriostatic or sterile water; expect a blue-tinted solution
✓Avoid contact with reducing agents (ascorbic acid destabilises Cu²⁺)
✓Aliquot reconstituted solution for freeze/thaw minimisation
✓Verify blue colour and CoA HPLC ≥98% before use

Common research-handling mistakes

Learnt from thousands of researcher orders across our UK labs.

✗ Buying GHK without copper

Fix: Confirm the CoA reads GHK-Cu (copper-bound); free GHK is a different pharmacology.

✗ Mixing with vitamin C in solution

Fix: Ascorbate reduces Cu²⁺ to Cu⁺ and destabilises the complex, keep them separate.

✗ Exposing to sunlight

Fix: Store in amber vial or foil-wrapped container at 2–8 °C.

Continue researching

Peer-reviewed guides, comparators and matched reference materials.

Primary sources & clinical trials

Peer-reviewed research and registered trials from PubMed, ClinicalTrials.gov, PubChem, FDA and NIH. All links open in a new tab and point to the primary source, so every claim can be verified at origin.

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Written and reviewed by

The UK Peptides Editorial Team · Research library, UK Peptides

The editorial team is responsible for supplier selection, batch release decisions and the content published in this research library. Every article here is sourced to primary literature and every product page to a signed third-party certificate. Corrections are made in place and the review date updated.

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The Molecular Structure of GHK and Its Copper Complex