What is GHK-Cu?
The molecular reference for this catalog describes the structure as glycyl-L-histidyl-L-lysine coordinated to copper(II), and the formula C14H24CuN6O4 makes the metal an integral part of the molecule rather than an additive. Coordination involves the amino terminal nitrogen, the deprotonated amide nitrogen, and the histidine imidazole, which makes the complex square planar and intensely blue. The colour is a direct readout of an intact complex.
The free tripeptide occurs in plasma and is reported to decline with age, which is what drew attention to it. In fibroblast culture the complex has been examined for effects on collagen and glycosaminoglycan synthesis markers, metalloproteinase expression, and copper dependent enzyme activity, and rodent wound models have studied granulation tissue formation in the animals used (Pickart and Margolina, 2018).
What is not settled is how much of the observed activity belongs to the peptide and how much to copper delivery itself, since copper salts alone alter many of the same readouts. Redox cycling of copper in culture medium can also generate reactive species independently of any receptor pathway.
Reconstitution & handling
Sterile or bacteriostatic water is added slowly down the vial wall, and the powder dissolves within seconds to a clear blue solution. Chelating buffers and reducing agents are avoided, since both strip or reduce the coordinated copper, and concentrated phosphate precipitates copper species. Concentration is simple division, so 2 mL added to a 50 mg vial yields 25 mg per millilitre.
Storage & stability
Sealed vials are stored at -20 °C, protected from light and moisture, and equilibrated to room temperature before opening, as the hygroscopic complex readily takes up water. Reconstituted solution is refrigerated at 2 to 8 °C in amber or foil wrapped vials because the copper complex is photosensitive, aliquoted for single use, and protected from repeated freezing and thawing. Contact with stainless steel and with reducing agents such as ascorbate or thiols is avoided, and any shift from blue toward green or colourless indicates degradation.
How it's tested
Lots are analysed by reversed phase HPLC at 214 and 220 nm and reported at 99 percent or greater, with the visible absorbance band near 620 nm serving as a direct measure of the intact copper complex. Mass spectrometry confirms identity against the theoretical mass of 403.92 from C14H24CuN6O4, and the copper isotope pattern is distinctive. Copper content is verified separately so the metal to peptide ratio is correct.