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Research use only
· 7 min read
A naming mess so bad that a chunk of the GHK-Cu listings online are quietly citing the wrong molecule. The compound itself is straightforward enough - the copper(II) complex of the tripeptide glycyl-L-histidyl-L-lysine, a three-residue sequence that nature apparently found useful enough to put in blood plasma. The database situation is less tidy. PubChem carries two records with the same constitutional skeleton, and searching for GHK will happily surface either one depending on what day it is. This post lays out the verified identifiers, the coordination chemistry, the study designs in the published literature, and what a researcher needs to know at the bench. Supplied by Kovalabs strictly as a research reagent; everything below describes what published studies have investigated, not any human use.
| Compound | GHK-Cu (copper complex of glycyl-L-histidyl-L-lysine) |
|---|---|
| Parent peptide / synonyms | GHK; Gly-His-Lys; INCI Copper tripeptide-1 |
| Class / mechanism | Copper(II)-binding tripeptide coordination complex |
| Molecular formula (free GHK) | C14H24N6O4 |
| Molecular weight (free GHK) | 340.38 g/mol |
| CAS (free GHK / Copper tripeptide-1 parent) | 49557-75-7 |
| PubChem CID (free GHK, L,L) | 73587 |
| Neutral 1:1 complex (descriptive) | C14H22CuN6O4, approx. 401.9 g/mol |
GHK is glycyl-L-histidyl-L-lysine: glycine, L-histidine and L-lysine in sequence (Gly-His-Lys). The stereodefined L,L peptide resolves in PubChem to CID 73587, molecular formula C14H24N6O4, molecular weight 340.38 g/mol, InChIKey MVORZMQFXBLMHM-QWRGUYRKSA-N. That record also carries CAS 49557-75-7 and the INCI designation Copper tripeptide-1. The CID, CAS, formula and molecular weight are mutually consistent for the free peptide, so that triple is the right anchor for citation.
Here is the trap. PubChem carries a second record, CID 342538, with the identical constitutional skeleton (InChIKey prefix MVORZMQFXBLMHM) but the stereochemistry left unspecified, suffix -UHFFFAOYSA-N. It is not the same stereochemical entity. The one to cite is CID 73587, the stereodefined L,L peptide; CID 342538 is a different record and should not be used as a reference for the copper complex.
The copper complex itself does not resolve to a single authoritative PubChem record. It is distributed across cationic, neutral and anionic protonation states and across 1:1 and bis-peptide stoichiometries, and the literature reports divergent CAS numbers across them. Because no single CID, CAS and formula triple co-resolves to one canonical GHK-Cu record, the complex is described here as the neutral 1:1 stoichiometry C14H22CuN6O4 (approximately 401.9 g/mol), and a disputed CID is not reported rather than guessing. The free-peptide identifiers above remain the verified citation anchor. The GHK-Cu product page links to batch documentation; the full research-use position is at our Research disclaimer.
| Property | Free GHK tripeptide | Neutral 1:1 GHK-Cu complex |
|---|---|---|
| Identity | Glycyl-L-histidyl-L-lysine | Cu(II) coordinated to GHK |
| Molecular formula | C14H24N6O4 | C14H22CuN6O4 (descriptive) |
| Molecular weight | 340.38 g/mol | approx. 401.9 g/mol |
| PubChem CID | 73587 (verified, L,L) | No single canonical CID (split by charge / stoichiometry) |
| CAS | 49557-75-7 | Variously listed; not a single canonical value |
| Metal centre | None | One Cu(II) in an N-donor coordination sphere |
GHK is defined by its copper-binding behaviour. The free peptide binds Cu(II) with an affinity comparable to the copper transport site on serum albumin, placing it among the naturally occurring high-affinity copper(II) chelators of blood plasma alongside the albumin DAHK motif. That is a coordination-chemistry property of the molecule, described here without any physiological outcome attached to it.
The coordination sphere has been characterised spectroscopically over several decades. An optical, EPR and electron spin-echo study of the 1:1 Cu(II) complex at neutral pH found the copper ion equatorially coordinated by nitrogen donors, with one nitrogen located in the histidyl imidazole ring (Freedman et al., Biochemistry, 1982; PMID 6291585). A later combined X-ray and solution study by Hureau et al. (Chemistry - A European Journal, 2011; PMID 21780203) resolved the geometry further: the monomeric complex in solution binds Cu(II) through three nitrogen ligands - the N-terminal amine, a deprotonated amide nitrogen and the imidazole nitrogen - with the fourth equatorial position occupied by a labile carboxylate oxygen. In the solid state the complex is dimeric rather than monomeric, a structural difference worth noting when comparing solution and crystallographic data. The same study reported the redox behaviour: the Cu(II)-GHK complex is inert under moderate redox potentials but can be reduced to Cu(I) at around -0.62 V with subsequent release of the copper ion.
These structural facts explain why the free peptide and the copper complex are treated as distinct chemical species. Forming the neutral 1:1 complex replaces coordinating protons with the metal centre, changing both formula and mass - which is also why reporting the copper-complex identifiers separately from the free-peptide identifiers is not pedantry but a practical necessity for any researcher trying to characterise a batch.
The following entries summarise the design and named endpoints of published work. No result, effect size, benefit, or human outcome is asserted; each entry is reported as study design and endpoint name only.
In a dermal-fibroblast culture model, Simeon et al. (Life Sciences, 2000; PMID 11045606) applied GHK-Cu to cells with endpoints being the measured levels of matrix metalloproteinase-2 protein and mRNA and the secretion of TIMP-1 and TIMP-2, compared against copper ions and GHK alone. A separate fibroblast study by Pollard et al. (Archives of Facial Plastic Surgery, 2005; PMID 15655171) cultured normal and irradiated primary human dermal fibroblasts in serum- and growth-factor-free media with or without GHK-Cu; the endpoints were population-doubling time and the measured autocrine levels of basic fibroblast growth factor, transforming growth factor beta-1 and vascular endothelial growth factor.
The most-cited animal work is not large - 72 rats, randomised to saline or one of two GHK-Cu concentrations in an ACL-reconstruction model (Fu et al., Journal of Orthopaedic Research, 2015; PMID 25731775), measuring knee-laxity side-to-side difference, graft pull-out stiffness and ultimate load, gait parameters and histological score. The trial measured what it measured; nothing a marketing page would quote is asserted here. A physico-chemical study by Bossak-Ahmad et al. (International Journal of Molecular Sciences, 2020; PMID 32867146) characterised a ternary Cu(II) complex of GHK with trans-urocanic acid by circular dichroism and electron spin resonance, with endpoints of binding affinity and complex stoichiometry.
These are published study designs and endpoint names only; no result or biological effect is asserted.
GHK-Cu is typically supplied as a lyophilised solid. As a generic bench procedure, lyophilised material is reconstituted by adding a measured volume of an appropriate laboratory solvent down the vial wall and allowing it to dissolve without vigorous agitation, with the volume chosen to give a target working concentration for the assay in hand. This describes preparation of a research reagent and is not a preparation method for any use in humans or animals. For the general workflow, see the Reconstitution guide.
On storage, lyophilised GHK-Cu is generally held sealed at around -20 degrees C, protected from light and moisture; reconstituted solution is kept refrigerated, protected from light, and used within a defined working window for analysis. Repeated freeze-thaw cycles and prolonged light or air exposure are avoided to preserve the copper-peptide complex. These are indicative figures and vary between suppliers, so the batch-specific Certificate of Analysis governs any given lot.
Peptide identifiers are easy to get wrong on paper, and a vial that states one thing is not the same as a vial that is one thing. That gap is what a Certificate of Analysis closes: research-grade GHK-Cu is characterised by HPLC for peptide purity, and a complete Certificate of Analysis for the complex confirms both peptide identity and purity and the copper content of the batch, giving lot-level traceability. For batch-level identity and purity data on other peptides in the catalogue, see their product pages and the corresponding Certificates of Analysis.
Tier one is the firm ground: the chemistry. GHK is a verified tripeptide, glycyl-L-histidyl-L-lysine, with a clean free-peptide identifier triple (CID 73587, CAS 49557-75-7, C14H24N6O4) and a coordination sphere resolved by spectroscopy and X-ray work; its copper(II) binding and presence among the chelators of blood plasma are well characterised. Tier two is softer: the mechanism and structure-activity work sits in dermal-fibroblast cultures and a single rat ACL-reconstruction model, reported by design and endpoint name only - and a cell in a dish is not a person. Tier three is the weakest: there is no human outcome data summarised here at all. It is not a licensed medicine, and it has not been shown to produce defined outcomes in humans. Curiosity is warranted; certainty is not.
GHK-Cu supplied by Kovalabs is a research chemical intended solely for laboratory investigation by qualified researchers. It is not a medicine, a cosmetic, a food or a supplement, and it is not for human or veterinary use, administration or consumption. Nothing in this post describes or implies a therapeutic effect, clinical benefit, dose, or route of administration; published studies are summarised by design and endpoint name only, with no outcome asserted. Full terms are set out in our Research disclaimer.
GHK-Cu is the copper(II) complex of the tripeptide glycyl-L-histidyl-L-lysine (Gly-His-Lys), grouped by its copper-coordination chemistry as a copper-binding tripeptide. Kovalabs supplies it for research use only, not for human or veterinary use.
For the stereodefined L,L free peptide, cite PubChem CID 73587, CAS 49557-75-7, molecular formula C14H24N6O4 and molecular weight 340.38 g/mol. Avoid CID 342538, which shares the same constitutional skeleton but is the stereochemically unspecified form and is not the correct record for the L,L peptide.
The copper complex is split across multiple PubChem records by protonation state and by 1:1 versus bis-peptide stoichiometry, with divergent CAS numbers in the literature. No single CID, CAS and formula triple co-resolves cleanly, so the neutral 1:1 stoichiometry is described as C14H22CuN6O4 (about 401.9 g/mol) without reporting a disputed CID.
Structural studies describe the monomeric solution complex binding Cu(II) through three nitrogen ligands - the N-terminal amine, a deprotonated amide nitrogen and the imidazole nitrogen - with a labile oxygen at the fourth equatorial site in the solid state (Freedman et al., 1982; Hureau et al., 2011).
Published work includes in-vitro fibroblast assays with matrix metalloproteinase-2 and growth-factor endpoints, an animal ACL-reconstruction model, and physico-chemical characterisation of ternary copper coordination. These are reported here as study designs and endpoint names only; no effect, benefit or human outcome is asserted.
It is typically supplied lyophilised, reconstituted in an appropriate laboratory solvent to a target assay concentration as a bench procedure, and stored cold and protected from light. Purity is verified by HPLC and confirmed alongside copper content on the batch Certificate of Analysis. See Reconstitution guide and Certificates of Analysis.