GHK-Cu

GHK-Cu is the copper(II) complex of the tripeptide glycyl-L-histidyl-L-lysine (Gly-His-Lys). Alphex supplies it as a blue lyophilised powder in 50 mg and 100 mg vials from UK stock, for laboratory and in-vitro research. Every batch is tested by reverse-phase HPLC at an independent laboratory, and the certificate is published in our public COA library before the batch is listed.

For research purposes only. This product is supplied exclusively for scientific laboratory research and analytical applications. It is not intended for human or animal use, and must not be misused in any way that contravenes regulations or applicable laws.

What GHK-Cu is

GHK is one of the shortest biologically studied peptides: three residues, glycine, histidine and lysine, joined by two peptide bonds. On its own the free tripeptide is a colourless compound with a molecular weight of 340.4 g/mol. GHK has a high affinity for copper(II), and the complex it forms, GHK-Cu, is the form most of the research literature works with. In the complex the copper ion is held by the nitrogen of the histidine imidazole ring, the free amino group of glycine and a deprotonated backbone amide nitrogen between glycine and histidine. That coordination is what gives GHK-Cu its colour: the powder is blue, and a solution is blue to blue-violet depending on concentration and pH.

The distinction between the free tripeptide and the copper complex matters for anyone comparing suppliers. They are different substances with different masses, different colours and different chemistry. A white or off-white powder sold as GHK-Cu is either the free tripeptide or something else, whatever the label says. The copper complex has a molecular weight of 403.9 g/mol, and that is the figure a certificate or specification for GHK-Cu should be consistent with.

You will also see GHK-Cu listed under other names. "Copper tripeptide-1" is the cosmetic-ingredient name. "Prezatide copper" is the non-proprietary name, and some listings describe the material as prezatide copper acetate, because synthetic peptides are commonly isolated as acetate salts. Naming conventions vary between catalogues, so the sequence, the colour and the mass basis are a better check than the name on the vial.

Specification notes

The full specification table for this product, including sequence, molecular formula, molecular weight, CAS number and storage, is printed further down this page. A few points about what those figures mean in practice:

• Mass basis. The 50 mg and 100 mg figures are the nominal fill of lyophilised material in the vial. They are not a net peptide content figure, and Alphex certificates do not report net peptide content. Counter-ions and residual water make up part of the mass of any lyophilised peptide.
• Purity. The purity specification is 99+% by reverse-phase HPLC with UV detection. That figure is the share of the UV signal at the detection wavelength that sits in the main peak. It measures how much of the detectable material is the target compound relative to related impurities. It is not a measure of copper content.
• Appearance. A blue lyophilised cake or powder, which may break up in transit. A loose powder is normal; a green tint, brown discolouration or visible moisture is not.
• Vial. Glass vial with a rubber septum and crimp seal, vacuum-sealed for transit.

Where GHK-Cu appears in the research literature

GHK-Cu has one of the larger literatures of any short peptide, almost all of it in cell culture, tissue models or analytical chemistry. Laboratories typically use it in:

• Gene-expression profiling. Microarray and connectivity-mapping studies that record how the expression of large gene sets changes in cultured cells exposed to the complex.
• Fibroblast and matrix assays. In-vitro work that measures collagen, glycosaminoglycan and metalloproteinase expression in dermal fibroblast cultures.
• Copper coordination chemistry. Studies of the binding constants, the species present at different pH values, and how the peptide exchanges copper with other ligands such as albumin.
• Oxidation chemistry. Assays of the complex's behaviour in redox systems and as a copper carrier.
• Formulation science. Stability of the complex in different vehicles, which is one reason GHK-Cu is used in larger quantities than most research peptides and is sold in 50 mg and 100 mg vials.

None of this literature establishes a use for the material outside a research setting. Alphex supplies GHK-Cu as a laboratory reagent and does not provide protocols, application guidance or advice on use beyond the bench.

Handling and storage in the lab

Sealed vials

Store sealed vials at -20 C for long-term storage, or at 2-8 C if the vial will be opened within a few weeks. GHK-Cu is light sensitive: keep it in the original vial in the dark, or wrap the vial to exclude light. The powder is hygroscopic, so let a cold vial reach room temperature before you open or puncture it. Opening a cold vial pulls condensation onto the powder, and water uptake makes weighing less accurate and accelerates degradation.

Reconstitution

The complex is highly water-soluble. Bacteriostatic water, sterile water or a suitable buffer can all be used, depending on the assay. Add the solvent slowly down the inside wall of the vial and swirl gently rather than shaking. A clear blue solution is expected.

Copper coordination depends on pH, which is the most common source of problems with GHK-Cu stocks:

• Strongly acidic conditions protonate the coordinating nitrogens and release copper from the peptide.
• Strongly alkaline conditions can precipitate copper as copper hydroxide.
• Most laboratories work between about pH 6 and 7.5.
• Chelating agents such as EDTA and high concentrations of citrate will strip the copper. Avoid them unless that is the point of the experiment.

Stock solutions

Keep reconstituted stock at 2-8 C in the dark and use it within a few weeks. For longer storage, split it into single-use aliquots and freeze at -20 C so each aliquot is thawed only once. A colour shift from blue towards green, cloudiness or a precipitate points to copper loss or degradation, and that stock should be discarded rather than used for quantitative work.

Concentration is simple arithmetic: mass divided by volume. Reconstituting a 50 mg vial with 5 mL gives a nominal 10 mg/mL stock. Using the complex's molecular weight of 403.9 g/mol, that is about 24.8 mM. Remember that this is a nominal figure based on vial fill, not on net peptide content.

How the batch certificate works

Every Alphex batch is sent to Vanguard Laboratory, an independent analytical laboratory, before it is listed. The laboratory runs reverse-phase HPLC with UV detection and reports the purity of the main peak with the chromatogram. Vanguard is accredited to ISO/IEC 17025:2017 by A2LA under certificate 6377.01. The chromatographic purity result is not represented as an accredited-scope test.

Both the 50 mg and 100 mg vials currently on sale are from lot 0010, vial label #0010-GHK. The certificate for that lot was run on a 50 mg vial, and the laboratory reported purity of greater than 99.80% (plus or minus 0.18%) by HPLC-UV/VIS on 27 December 2025.

To check your own vial, open the COA library and type in the batch code printed on the vial label. The library shows the full certificate image, the laboratory reference, the date and the status of each lot. Superseded lots stay in the library, and so does a lot that failed our 99+% acceptance threshold, marked Rejected.

Be clear about what the certificate covers. It is an RP-HPLC purity result. It does not report mass spectrometry, endotoxin, water content or net peptide content, and Alphex does not claim those tests for its batches.

Checking GHK-Cu from any supplier

GHK-Cu is sold for laboratory research and as a cosmetic-science ingredient, so quality and labelling vary widely. Whoever you buy from, these checks take a few minutes:

1. Colour. The powder should be blue. White or off-white material is not the copper complex.
2. Mass basis. The specification should be consistent with the complex at 403.9 g/mol, not the free tripeptide at 340.4 g/mol.
3. Certificate. Look for a certificate with a lot number that matches the vial label, a chromatogram, a purity figure and the name of the issuing laboratory.
4. Method. Check which test the certificate actually reports, and do not assume it covers anything else.
5. Solution behaviour. A fresh solution in a near-neutral vehicle should be clear and blue. Persistent cloudiness or a green tint on first reconstitution is a reason to stop and query the batch.

The same checklist, extended to every compound, is in our note on how to read a research peptide COA.

Vial sizes

Both sizes currently on sale are from lot 0010. The 50 mg vial suits a stock that will be used up within its useful life once reconstituted. Concentrations are nominal, based on vial fill rather than net peptide content.

Further reading

• GHK-Cu copper peptide: chemistry, research uses, handling and COA
• GHK versus GHK-Cu: free tripeptide and copper complex
• Light-sensitive peptides: which ones and how to handle them
• How to read a research peptide COA

Alphex GHK-Cu is supplied to laboratories and researchers for in-vitro research only. Delivery is UK only, by Royal Mail Tracked 24, which aims for the next working day.