GHK-Cu Peptide: How It Differs From GHK
GHK and GHK-Cu are often treated as the same thing, and both turn up regularly among the research peptides people in the UK search for, but they are not the same. GHK is a tiny peptide made of three amino acids: glycine, histidine and lysine. GHK-Cu is that same peptide holding on to a copper ion. The copper changes how the molecule behaves, so it helps to know which one a study is talking about.
What Is GHK?
GHK is glycyl-L-histidyl-L-lysine, three amino acids joined together, with a weight of about 340 daltons (see the PubChem record). It was first described in 1973 by Pickart and Thaler, who found it in human serum and showed it helped liver cells survive in culture. A later review from Pickart's group says it was isolated from a blood protein called albumin. The same three-amino-acid sequence also appears in type I collagen. Our introduction to GHK-Cu covers how the copper form is usually described.
How Does GHK Hold Copper?
In 1980, Pickart's group reported that GHK binds copper(II) and increases copper uptake in cultured liver tumour cells, and they suggested it works as a copper carrier. The copper is held by three nitrogen atoms: one from the amino group at the start of the chain, one from the link between glycine and histidine, and one from the ring on histidine. A fourth spot stays open and is usually taken by a water molecule. In the lab, the complex absorbs light at around 606 nm.
How Tightly Is the Copper Held?
Very tightly. At pH 7.4 the binding is strong enough that the dissociation constant sits well below one picomolar. It loosens as conditions become more acidic, to about 20.9 picomolar at pH 6.5. A second GHK molecule can join the copper complex, but only weakly. Because binding changes with pH and with what else is in the solution, the form and purity of the material matter, and the reports on our lab reports page show how a given batch was checked.
Cells keep free copper very low because loose copper can produce damaging hydroxyl radicals. Carrier proteins such as Atox1, CCS and Cox17 move it where it is needed, as summarised in this review of copper transport in cells. One chemistry study also found that copper bound to albumin is almost impossible to reduce in serum, while copper bound to GHK can be reduced by glutathione.
What Have Cell and Animal Studies Reported?
In 1988, Maquart and colleagues found that GHK-Cu increased collagen production in cultured fibroblasts. The effect started at about one trillionth of a mole per litre, peaked near one billionth, and did not change the number of cells. Later lab work reported that GHK and GHK-Cu also affected the breakdown of collagen and glycosaminoglycans.
In a 1993 rat study that used implanted wound chambers, GHK-Cu raised collagen and glycosaminoglycan content, while a control tripeptide did nothing.
Some gene-expression claims about GHK come from Connectivity Map searches. These compare patterns in cell-line data and show matches, not measured effects.
Because the two forms behave differently, any methods section should state which was used. The copper form is the one supplied as GHK-Cu copper peptide 100mg lyophilised.
Important: This article is for scientific information only. The peptides discussed are intended exclusively for scientific and laboratory research and are not intended for human or veterinary consumption, administration, diagnosis, treatment or therapeutic use.