The molecule and its copper chelate
GHK-Cu’s behavior starts with its structure: a short glycyl-L-histidyl-L-lysine chain that folds around one copper(II)…
Three amino acids that grip a single copper ion
GHK-Cu’s behavior starts with its structure: a short glycyl-L-histidyl-L-lysine chain that folds around one copper(II) ion, holding it through nitrogen donors rather than leaving it loose in solution. Spectroscopy on the dissolved complex places the copper equatorially coordinated by two or three nitrogen atoms, one of them in the histidine imidazole ring. That coordination is what turns a reactive metal into a controlled, deliverable cargo.
This unit reads the molecule residue by residue, explains why its copper affinity is so unusually high, and shows why a chelate behaves nothing like a copper salt. Settled analytical chemistry here, not biology, is the firmest ground in the whole course.
Key terms
The copper chelate, in 3D
The linear G-H-K sequence folds into a compact copper chelate: nitrogen donors from the peptide backbone, which is the spine the three building blocks are strung together on, and from the histidine side chain, which is the piece that hangs off one of those building blocks, wrap a single copper(II) ion. Each building block in a chain like this is called a residue. Click an atom to see the role it plays. The diagram draws the common textbook picture, which a 2015 review states: the glycine amino nitrogen, the deprotonated amide nitrogen of the glycine-histidine peptide bond (the link joining those two building blocks), and the histidine imidazole nitrogen, with no lysine nitrogen among them, adding that in solution lysine carboxyl groups of neighboring complexes may take part. Read it as a schematic: the fetched spectroscopy reports two or three coordinating nitrogens, and electron spin-echo work places one of them in the histidyl imidazole ring; it does not assign the others residue by residue.
Coordination is the whole story: a bare copper salt leaves the metal loose, while this chelate holds it through defined nitrogen contacts. The same spectroscopy is explicit that the solid-state form, with oxygen-bridged copper pairs, does not exist in solution, so the crystal picture and the dissolved molecule are not the same object. That is why GHK-Cu is studied as a delivery system for copper rather than a copper supplement.