What Is GHK-Cu?
GHK-Cu is the copper(II) chelate of the tripeptide Glycyl-L-Histidyl-L-Lysine (GHK), a sequence identified endogenously in human plasma, saliva, and urine. The tripeptide was first isolated and characterised by Pickart and Thaler in the 1970s during investigations into plasma factors affecting hepatocyte proliferation. Its molecular formula is C14H24CuN6O4, with a molecular weight of 403.92 Da for the copper complex.
The compound is water-soluble, forms a stable blue solution in aqueous media, and has been widely used as a model compound in coordination chemistry and biological chemistry research.
Copper Coordination Chemistry
The biological activity of GHK is inextricably linked to its coordination of copper(II) ions. The tripeptide acts as a tridentate ligand, binding Cu2+ through the α-amino terminus, the deprotonated amide nitrogen of the glycine–histidine peptide bond, and the imidazole nitrogen of the histidine side chain. This square-planar coordination geometry confers exceptional thermodynamic stability, with a reported association constant (log Ka) of approximately 16.4 for the GHK–Cu2+ complex.
This high-affinity copper binding has important implications for copper transport research: GHK–Cu acts as a carrier capable of delivering Cu2+ ions to cuproenzymes and copper-dependent metalloenzymes under physiological ionic conditions. Comparative binding studies position GHK–Cu with a higher copper affinity than albumin under certain pH conditions, making it a useful research model for intracellular copper trafficking studies.
Antioxidant and Redox Properties
Copper-binding peptides can in principle act as either pro-oxidant or antioxidant species, depending on coordination geometry and local redox environment. Research on GHK–Cu has demonstrated:
- Superoxide Dismutase (SOD)-Like Activity: The Cu2+/Cu+ redox cycle within the GHK–Cu complex enables catalytic dismutation of superoxide radicals (O2•−) in cell-free assays, mimicking the activity of Cu/Zn-SOD. The mechanism involves Cu2+ reduction by O2•− followed by re-oxidation, generating H2O2 and O2.
- Lipid Peroxidation Studies: GHK–Cu has been investigated in liposome membrane models, where it has shown inhibitory activity against iron-catalysed lipid peroxidation, attributed to competitive metal chelation rather than direct radical scavenging.
- Fenton Reaction Research: By sequestering free copper ions, GHK can reduce the availability of Cu2+ for participation in Fenton-type reactions — a mechanism studied in the context of oxidative stress biology.
Extracellular Matrix and Collagen Research
GHK–Cu has been extensively used as a research tool in dermal biology and connective tissue research, where copper-dependent enzymes play key structural roles:
- Lysyl Oxidase Activation: Lysyl oxidase (LOX) is a copper-dependent amine oxidase essential for crosslinking of collagen and elastin fibres. Research has shown that GHK–Cu can serve as a copper source for LOX-dependent crosslinking reactions in fibroblast culture models, enabling mechanistic investigation of ECM assembly.
- Collagen Synthesis in Fibroblast Models: Cell culture studies using dermal fibroblast lines have reported upregulation of collagen type I and type III mRNA expression in response to GHK–Cu treatment, with proposed mechanisms involving TGF-β pathway modulation.
- MMP and TIMP Regulation: GHK–Cu has been observed to modulate the balance of matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) in fibroblast assays, a relationship studied in the context of ECM turnover and remodelling research.
Gene Expression Research
Broad transcriptomic analysis using microarray and RNA-seq approaches in cell culture models has identified GHK–Cu as a compound that influences expression of a wide gene set. Published datasets report modulation of genes associated with inflammation response pathways (NF-κB targets), DNA repair mechanisms, and mitochondrial function in a concentration-dependent manner. These datasets are available in public repositories and form a basis for further mechanistic hypothesis generation in molecular biology research.
Research Grade Specifications
GHK-Cu supplied by PeptidesNextDay is manufactured to ≥98% purity as confirmed by reverse-phase HPLC. ESI mass spectrometry confirms the expected [M+H]+ ion at m/z 341.1. The compound is supplied as a lyophilised blue powder and is freely soluble in sterile water. Storage is recommended at −20 °C, protected from light. As with all copper-containing compounds, preparation should be conducted using metal-free plasticware and buffers where experimental accuracy requires minimal background copper interference.
All batches are independently tested by a UKAS-accredited laboratory, with a full certificate of analysis provided at time of dispatch.