What is the difference between GHK and GHK-Cu?

GHK is the free tripeptide; GHK-Cu is the same peptide coordinated to copper(II). The complex is the species studied in most published dermal research, and the two have different molecular weights and activity profiles.

Why does GHK-Cu need protection from light and reducing agents?

The complex is light-sensitive, and reducing agents such as ascorbic acid reduce copper(II) and dissociate the complex. Chelators like EDTA competitively strip the copper, leaving free peptide instead of the intended species.

What does loss of blue colour in a GHK-Cu solution indicate?

The blue colour comes from the coordinated copper centre. Loss of colour indicates the complex has dissociated, and the solution should not be used for work that depends on the coordinated form.

Compound overviews · 6 min read

GHK-Cu and copper peptides in dermal research

The copper coordination that defines this class, reported effects on matrix remodelling, and the handling constraints that copper chemistry imposes in the laboratory.

A tripeptide with a metal centre

GHK is a three-residue peptide — glycyl-L-histidyl-L-lysine — that occurs naturally in plasma and whose concentration declines with age. Its research interest derives almost entirely from its high affinity for copper(II), which it coordinates to form the GHK-Cu complex.

The complex, not the free peptide, is the active species in most published work. This distinction matters commercially: GHK and GHK-Cu are separate products with different molecular weights, different appearance — GHK-Cu is a distinctive blue — and different reported activity profiles.

Reported activity in dermal models

The published literature describes effects on extracellular matrix turnover: stimulation of collagen and glycosaminoglycan synthesis in fibroblast culture, modulation of matrix metalloproteinase and TIMP expression, and antioxidant behaviour attributed in part to the copper centre's role in superoxide dismutase-like activity.

A separate strand of work reports gene-expression modulation across a broad transcript set in cultured fibroblasts, and effects on wound-margin behaviour in animal models. As with most of this class, the evidence base is preclinical and in vitro.

Handling copper chemistry

GHK-Cu imposes constraints that peptide-only compounds do not. It is light-sensitive and should be handled in amber vessels or protected from ambient light. It is incompatible with strong reducing agents, including ascorbic acid, which reduces copper(II) and dissociates the complex — a common and easily missed source of failed experiments in combined-formulation work.

It also chelates. In buffers containing EDTA or other chelating agents the copper is competitively stripped, leaving free peptide and free chelate rather than the intended complex. Check buffer composition before assuming a null result reflects biology.

Solutions are blue; loss of colour indicates the complex has dissociated and the material should not be used for work that depends on the coordinated form.

Frequently asked questions

What is the difference between GHK and GHK-Cu?: GHK is the free tripeptide; GHK-Cu is the same peptide coordinated to copper(II). The complex is the species studied in most published dermal research, and the two have different molecular weights and activity profiles.
Why does GHK-Cu need protection from light and reducing agents?: The complex is light-sensitive, and reducing agents such as ascorbic acid reduce copper(II) and dissociate the complex. Chelators like EDTA competitively strip the copper, leaving free peptide instead of the intended species.
What does loss of blue colour in a GHK-Cu solution indicate?: The blue colour comes from the coordinated copper centre. Loss of colour indicates the complex has dissociated, and the solution should not be used for work that depends on the coordinated form.