GHK-Cu

What is GHK-Cu?

GHK-Cu is the copper(II) complex of the tripeptide glycyl-L-histidyl-L-lysine (C₁₄H₂₄CuN₆O₄, 403.9 g/mol, CAS 89030-95-5). The free tripeptide GHK occurs naturally in human plasma, saliva and urine, and was first isolated from plasma by Loren Pickart in 1973. Cu(II) is held in a square-planar coordination sphere by the N-terminal amine, the deprotonated glycyl amide nitrogen and the histidine imidazole, at a stability constant (log K approximately 16.4) close to that of the copper transport site on human serum albumin. This near-parity is the basis for the model of ghkcu as a physiological copper shuttle rather than an inert chelator. Supplied as lyophilised powder for in-vitro research use only.

GHK-Cu vs Copper-Free GHK

GHK and GHK-Cu are two distinct species, not two names for one compound. GHK is the free tripeptide (C₁₄H₂₄N₆O₄, 340.4 g/mol, CAS 49557-75-7); GHK-Cu carries one bound Cu(II) ion and is 63.5 g/mol heavier. The distinction is experimentally load-bearing. Molar calculations differ, the copper complex is blue while the free peptide is colourless, and the equilibrium between them shifts with the free copper, competing chelators, phosphate content and reducing agents present in the medium. Published work exists on both forms independently, including studies on copper-free GHK, so a protocol should state which species is intended and control the copper content of the medium accordingly. Researchers comparing GHK-Cu against other copper-binding sequences such as AHK-Cu should note that the loose trade term copper peptide covers several chemically different ligands.

GHK-Cu Research Applications

GHK-Cu appears in two largely separate research literatures. The first is extracellular matrix biology, where fibroblast culture and rat wound-chamber studies from the Maquart and Simeon groups (1988-2000) reported stimulation of collagen synthesis, sulfated glycosaminoglycan synthesis and small proteoglycan expression, alongside upregulation of matrix metalloproteinase-2 and its tissue inhibitors, a simultaneous increase in both matrix deposition and matrix turnover. Related in-vitro work reported increased integrin expression and p63 positivity in keratinocyte culture. The GHK motif occurs within the alpha-2(I) chain of type I collagen, so it is generally classified as a matrikine. The second literature is transcriptomic: Connectivity Map analyses reported by Pickart and colleagues indicate GHK alters expression of on the order of 4,000 human genes, and Campbell et al. (Genome Medicine, 2012) used that dataset to identify GHK as inversely correlated with an emphysema-related lung destruction signature, then examined collagen remodelling in cultured lung fibroblasts. More recent preclinical work has examined GHK-Cu in rodent models of pulmonary fibrosis, silicosis and airway remodelling, with oxidative stress and inflammatory signalling as the reported endpoints. Copper delivery to copper-dependent enzymes including lysyl oxidase and superoxide dismutase is the mechanism most commonly proposed to link these observations.

Reconstitution Guide

Allow vials to reach room temperature, then sterilise the rubber stopper of both the peptide vial and the bacteriostatic water vial with an alcohol swab. Slowly draw your bacteriostatic water into a sterile insulin syringe, then inject it gently down the inner glass wall of the peptide vial, never directly onto the lyophilised powder. Once added, gently swirl the vial in a slow circular motion until fully dissolved. Never shake or vortex. The solution should be clear and colourless. Label the vial with the reconstitution date and store immediately. GHK-Cu solution will be blue to blue-violet once reconstituted, from the d-d transition of the Cu(II) centre. This is expected. A colourless or green-tinged solution indicates the complex has been disrupted rather than simply diluted, and visible absorption spectrophotometry around 500-600 nm is the standard bench check on complex integrity. Reconstitute away from direct light and use glass or high-grade polypropylene labware, avoiding prolonged contact with chelating or metallic surfaces that can strip Cu(II) from the tripeptide.

See our full peptide reconstitution guide and reconstitution calculator for step-by-step protocol.

Storage Instructions

Lyophilised vials should be stored at -20°C, protected from light and moisture, and remain stable for up to 24 months. Once reconstituted with bacteriostatic water, store the solution at 2-8°C (standard refrigerator) and use within approximately 3 months. For storage beyond that, prepare single-use aliquots at -20°C, where reconstituted peptide remains stable for up to 6 months. Avoid repeated freeze-thaw cycles and always handle under sterile laboratory conditions. GHK-Cu is photolabile as a copper(II) peptide complex, so keep both lyophilised vials and reconstituted solution protected from UV and fluorescent light, using amber or foil-wrapped vessels for aliquots. Freeze-thaw cycling can disrupt the copper coordination sphere in addition to degrading the peptide backbone, so single-use aliquots are preferable to repeated access of a single stock.

Frequently Asked Questions

Research References

• Growth-modulating plasma tripeptide may function by facilitating copper uptake into cells (Nature, 1980)
• GHK-Cu stimulates matrix metalloproteinase-2 expression by fibroblast cultures (Life Sci, 2000)
• A gene expression signature of emphysema-related lung destruction and its reversal by the tripeptide GHK (Genome Med, 2012)
• GHK Peptide as a Natural Modulator of Multiple Cellular Pathways in Skin Regeneration (Biomed Res Int, 2015)

Related Research Compounds

• → GHK-Cu 50mg
• → BPC-157 5mg
• → Bacteriostatic Water 10ml