Compound Profile: GHK-Cu

GHK is the tripeptide glycyl-L-histidyl-L-lysine, molecular formula C14H24N6O4, molecular weight approximately 340.4 g/mol. GHK-Cu is its complex with a copper(II) ion, giving a molecular weight of roughly 403.9 g/mol. It is supplied as a blue lyophilised powder that dissolves to give a blue solution; the colour is intrinsic to the copper complex and is expected.

The peptide was isolated from human plasma in 1973 by Loren Pickart, who observed that plasma from younger donors had an effect on liver cells in culture that plasma from older donors lacked, and traced the activity to this tripeptide. Its concentration in plasma declines with age, an observation that has shaped much of the subsequent research.

GHK binds copper(II) with high affinity through the imidazole nitrogen of histidine, the terminal amine of glycine and the deprotonated amide nitrogen between them, forming a square-planar complex. The lysine side chain is not involved in copper binding and remains free. This binding geometry gives the complex its blue colour, with an absorption maximum in the visible region, and is the basis for its description in the literature as a copper-delivery molecule.

The largest body of work concerns skin and connective tissue. In fibroblast culture GHK-Cu is reported to increase synthesis of collagen, elastin and glycosaminoglycans, and it appears in numerous wound-model studies in animals. Gene-expression profiling studies have examined its effect on large numbers of genes in cultured cells. It is a standard reference compound in cosmetic formulation research and appears in a wide range of topical products. As with other research peptides, controlled human data outside the cosmetic context is limited.

GHK-Cu is analysed by reversed-phase HPLC for purity and by mass spectrometry for identity, with the copper complex giving a characteristic signature. The visible blue colour is itself a crude identity check: a colourless powder sold as GHK-Cu is either the free peptide or a different compound. Regent Peptides supplies GHK-Cu in 50 mg and 100 mg vials, UK manufactured, with every batch independently tested by Janoshik Analytical.

The complex is stable as a lyophilised solid when kept dry, cold and in the dark. In solution it should be refrigerated. Because copper can interact with reducing agents and some buffers, laboratories preparing solutions for assay work normally use plain sterile or bacteriostatic water and avoid thiol-containing additives.