GHK-Cu: A Primer on the Copper Tripeptide

GHK is a tripeptide — Glycyl-L-histidyl-L-lysine — first isolated from human plasma in 1973. In its naturally occurring form, the peptide carries a single copper(II) ion bound through the histidine imidazole, the N-terminal amine, and the α-carboxylate of glycine. The complex is referred to as GHK-Cu, the copper tripeptide.

What’s interesting about it

GHK plasma concentrations decline with age — from roughly 200 ng/mL at age 20 to about 80 ng/mL by age 60. This decline correlates loosely with reductions in cutaneous repair capacity. The correlation has driven research interest in GHK-Cu as both a cosmetic ingredient and a tissue-research compound.

Reported activity

In published in vitro and animal studies, GHK-Cu has been associated with:

• Stimulation of collagen and elastin synthesis in fibroblast cultures
• Upregulation of decorin and glycosaminoglycan production
• Modulation of metalloproteinase expression (MMP-1, MMP-2)
• Anti-inflammatory effects in oxidative-stress models
• Hair-follicle modulation in scalp-tissue assays

A frequently cited 2010 transcriptomic study reported that GHK-Cu affected the expression of nearly a third of all human genes in cultured fibroblasts — though the magnitude of those effects, and their translation to in vivo settings, is debated.

Cosmetic vs research formulation

GHK-Cu is a regulated cosmetic ingredient in many jurisdictions and appears in skincare products at concentrations typically below 1%. As a research compound, it is supplied as the lyophilized complex and reconstituted in buffered solution.

Stability

The copper-peptide bond is pH-sensitive. Below pH 4 the complex dissociates; above pH 8 the copper can precipitate. Reference solutions are commonly buffered to pH 6.5-7.0. Light degrades the complex over time — store in amber vials, refrigerated.

Sourcing notes

Look for suppliers that quantify both peptide purity (HPLC) and copper content. The molar ratio should be 1:1; excess free copper is a contamination flag.