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Compound deep-dive
GHK-Cu explained: the blue copper peptide.
Glycyl-histidyl-lysine bound to a single copper ion. First isolated from human plasma by Pickart in 1973. Fifty years of peer-reviewed research, a vivid cobalt-blue colour that tells you whether the synthesis is real, and a handful of supplier red flags that almost no buyer knows to check for.
What GHK-Cu actually is
GHK is a tripeptide: three amino acids in sequence – glycine, histidine, lysine – with the standard one-letter code GHK. On its own, GHK is a clear or very pale colourless powder. Bind a single copper(II) ion to it and the colour shifts to the deep cobalt blue that gives the complex its visual signature.
The copper sits at the centre of a square-planar coordination geometry, held in place by the imidazole nitrogen of the histidine side chain together with the deprotonated amide nitrogens of the peptide backbone. The free amino terminus and the carboxylate also participate in the coordination sphere. The result is a thermodynamically stable Cu(II)-peptide complex that is the form GHK takes in vivo at physiological pH.
| Sequence | Gly-His-Lys (single-letter: GHK) |
| Free-tripeptide MW | 340.39 g/mol |
| Copper-bound complex | GHK + Cu²⁺ (the form supplied as “GHK-Cu”) |
| CAS number (GHK-Cu) | 89030-95-5 |
| Coordination geometry | Square planar around Cu(II), histidine imidazole + backbone amides |
| Visible colour | Vivid saturated cobalt / royal blue |
| UV-Vis absorption | Broad d-d band centred around 590-620 nm |
| Stability (lyophilised) | 24+ months at 2–8 °C, sealed and protected from light |
| Light sensitivity | Photolabile – ship and store in amber glass |
How GHK-Cu was discovered
The story starts in 1973 with a biochemist called Loren Pickart, then at the University of California, San Francisco. Pickart was studying why human blood plasma from older donors lost the ability to keep cultured human liver cells in a healthy state, while plasma from younger donors maintained them indefinitely. The young-donor activity tracked with a small molecule that could be size-fractionated – too small to be a protein, but biologically active.
Pickart isolated the active fragment and identified it as a three-amino-acid peptide: glycyl-histidyl-lysine. Subsequent work demonstrated that the active species in solution was the copper(II) complex, GHK-Cu, and that the tripeptide was acting (at least in part) as a copper-transport vehicle – picking up Cu(II) from albumin in the bloodstream and shuttling it to cells where copper-dependent enzymes need it.
That fundamental observation has been the seed for fifty years of follow-up research across copper biology, dermatology, wound-research models, and gene-expression studies in cultured cells. We don’t make any therapeutic claim about it – the literature is for laboratory and in-vitro contexts only – but if you want to read the foundational papers, the seminal modern review is Pickart and Margolina, “Regenerative and Protective Actions of the GHK-Cu Peptide in the Light of the New Gene Data” (2018), International Journal of Molecular Sciences.
Why the colour matters
The colour IS the test.
Cu(II) in a nitrogen-rich coordination environment like GHK absorbs light strongly in the 590-620 nm region of the visible spectrum – the orange-red part of the rainbow. The eye sees the complement of what’s absorbed, which is why the powder appears intensely blue.
If the GHK is correctly synthesised and the copper is genuinely bound, the lyophilised cake should be a vivid, saturated cobalt blue. Like a deep ink. There should be no ambiguity about its colour from across the room.
Pale, washed-out, sky-blue, beige, off-white or “white-with-a-tint” powder labelled as GHK-Cu is one of the most common counterfeits in the market. It usually means one of three things: the copper was never coordinated (you’re being shipped raw GHK with a label that lies), the GHK itself is impure, or the sample has degraded under light or moisture during storage.
This is genuinely useful as a buyer because it’s a check you can do before you even open the Certificate of Analysis. Hold the vial up to a bright window. If it isn’t deep cobalt blue, walk away.
What to look for on the Certificate of Analysis
If you’ve read our walk-through of how to read a Janoshik HPLC report, you already know the structure. For GHK-Cu specifically, three things matter beyond the standard purity check:
1. The single dominant peak at the GHK-Cu retention time
On a reversed-phase HPLC chromatogram, GHK-Cu typically elutes earlier than free GHK because the copper complex changes the molecule’s polarity. You should see one tall peak (target) and a flat baseline elsewhere, with purity reported as 99%+ in the analytical summary. Multiple comparable peaks in the chromatogram suggest a mixture of GHK forms (fully copper-bound, partially copper-bound, free GHK) which is not what you ordered.
2. Mass spectrometry confirmation of the copper complex
Where the lab includes MS data, the molecular ion for GHK-Cu lands around m/z 401 in positive ion mode (the GHK ligand at 340.39 g/mol plus a single Cu²⁺ centre, minus two protons displaced by deprotonated amide nitrogens). If the only mass observed corresponds to free GHK, the copper isn’t there – end of story.
3. Storage and shipping conditions noted on the COA
Reputable labs note the receiving condition of the sample (refrigerated, ambient, frozen) and the analysis date. Because GHK-Cu is photolabile, a sample analysed weeks after production with no cold-chain handling notes should at minimum prompt a question to the supplier about storage between testing and shipping.
Storage and handling at your bench
- Refrigerate at 2–8 °C in the original sealed vial. Do not freeze the lyophilised cake; freeze-thaw cycles can cause the cake to fragment and increase surface area exposed to ambient moisture.
- Keep away from direct light. Amber glass vials are not optional for this compound. Even brief incidental exposure to bright sunlight or strong UV is best avoided.
- Reconstitute with bacteriostatic water by adding the water slowly down the inside wall of the vial and gently swirling (do not shake or vortex) until the cake fully dissolves. The resulting solution should be a clear deep blue with no precipitate.
- Reconstituted shelf life is shorter than the lyophilised form; refer to the published peer-reviewed analytical literature for the specific assay or research context you are running.
Common red flags when sourcing
Walk-away signals when buying GHK-Cu
- The powder shown in the supplier’s product photos is white, off-white, beige, or pale sky-blue – rather than vivid saturated cobalt blue.
- No batch-specific Certificate of Analysis included with the order, only a generic “we test our products” statement on the website.
- The COA has no verification key and no link to the issuing lab’s verification portal.
- Mass spectrometry confirmation is absent or shows only the GHK ligand mass without the copper-bound complex mass.
- The supplier ships GHK-Cu in clear glass vials rather than amber, with no temperature-controlled packaging.
- The lyophilised cake arrived as a fine loose powder rather than a solid puff or disc – freeze-drying done correctly produces a porous cake, not granules.
- The supplier offers GHK-Cu at a suspicious discount to the broader market rate. Real GHK-Cu requires copper-coordination chemistry done correctly and is not the cheapest peptide to synthesise.
Where this fits in the wider picture
GHK-Cu sits in the regenerative-research family alongside compounds like BPC-157, TB-500, and Thymosin Alpha-1. The chemistry is completely different from the others: GHK-Cu is the only one where a transition-metal coordination is essential to the molecule’s identity. That’s both what makes it interesting (a built-in colour test, a clear MS signature, a well-defined coordination geometry) and what makes counterfeits easier to spot if you know what to look for.
If you’re picking between GHK-Cu and the others for a particular research context, our side-by-side write-ups cover the chemistry and selection criteria:
- GHK-Cu vs BPC-157 – copper tripeptide vs pentadecapeptide
- GHK-Cu vs NAD+ – copper-binding vs nicotinamide cofactor
What we supply
We stock GHK-Cu as a lyophilised cake in 50mg and 100mg amber-glass vials, independently HPLC-verified by Janoshik Analytical. The Janoshik Certificate of Analysis ships in the box with every order where one is available for the current batch, and the report is also published on our Purity page for independent reference. If you’d like to see the product page with current pricing, vial-or-pen format, sizing options, and the integrated dose calculator, it’s at /peptides/ghk-cu.html.
Research use only. The compound information described above is drawn from peer-reviewed analytical and biochemical literature and is provided for laboratory and in-vitro research context. Pure Peptides Lab Ltd does not provide therapeutic claims, dosing guidance, administration protocols, or any content relating to human or veterinary use.
Marcus, founder of Pure Peptides Lab Ltd. UK-registered research-peptide supplier, Companies House number 16876166 . Writing on the technical side of the market that most suppliers prefer to leave fuzzy. Questions? WhatsApp or email - real human reply.