The Gly-His-Lys sequence, copper coordination, solubility and storage considerations for GHK-Cu as a standard.
Sequence and metal binding
GHK-Cu is built on the tripeptide Gly-His-Lys, where the imidazole side chain of histidine, together with backbone nitrogen atoms, provides the principal donor groups for binding copper(II). This coordination geometry defines the complex and underlies its distinctive spectroscopic signature in the visible region.
Composition and mass
The complex carries the molecular formula C14H24N6O4Cu and a molecular weight near 403.9 g/mol. The presence of copper makes elemental and spectroscopic analysis particularly informative, since the metal contributes characteristic features absent from the free peptide of the same sequence.
Solubility and color
GHK-Cu is water-compatible for laboratory preparation and shows a blue coloration in solution arising from copper d-d transitions. The intensity and stability of this color depend on pH and on the integrity of the metal-peptide coordination, factors a researcher monitors when preparing standards.
Stability considerations
Because the material is a metal complex, its stability depends on maintaining copper coordination; strongly chelating buffers or extreme pH can perturb the complex. The lyophilized solid is stored cold, dry and protected from light, and working solutions are prepared fresh and handled gently to preserve the complex.