Copper peptides: AHK-Cu vs GHK-Cu.
Copper peptides are short peptides bound to a copper(II) ion, and the two most often named are GHK-Cu and AHK-Cu. Their tripeptides differ by a single amino acid: alanine instead of glycine at the N-terminus. GHK-Cu has a large literature behind it; AHK-Cu has far less. Here is what separates them.
What the name covers.
Copper peptide is the common name for a small peptide that holds a copper(II) ion. The best known is GHK-Cu, the copper complex of glycyl-L-histidyl-L-lysine, a tripeptide that occurs naturally in human plasma and binds copper with high affinity. AHK-Cu is a synthetic analog made by swapping the first amino acid. Most of what is known about copper peptides comes from GHK-Cu work in cell culture and preclinical models, which is why the two are so often compared.
One residue apart.
| AHK-Cu | GHK-Cu | |
|---|---|---|
| Peptide | Ala-His-Lys (AHK) | Gly-His-Lys (GHK) |
| Residue 1 | Alanine, with a methyl side chain | Glycine, with no side chain |
| Origin | Synthetic analog | Naturally occurring; found in human plasma |
| Free tripeptide formula | C15H26N6O4 | C14H24N6O4 |
| Free tripeptide mass | 354.4 g/mol | 340.4 g/mol |
| Copper complex | AHK bound to copper(II) | GHK bound to copper(II), 400.90 g/mol as the complex |
| Published research | Little; its main primary study is a 2007 in vitro hair follicle study | Extensive, across cell culture, preclinical and structural work |
| At Helion | Not supplied | GHK-Cu 50mg (CU50) |
Tripeptide formulas and masses from Helion's peptide molecular weight calculator, matching PubChem; the GHK-Cu complex mass from PubChem.
How the tripeptides hold copper.
GHK is a naturally occurring, high-affinity copper(II) chelator found in blood plasma. Structural work found that in solution it binds copper through three nitrogen atoms: the N-terminal amino group, the amide nitrogen between glycine and histidine, and the imidazole ring of histidine, with a labile oxygen in the fourth position. AHK keeps the same layout of a free N-terminal amine followed by histidine; its only change is the extra methyl group on the first residue.
Very different depth.
GHK-Cu is one of the most widely cited peptides in cell-culture and preclinical work on skin, connective tissue and gene expression. AHK-Cu's record is much thinner. Its best-known primary study, from 2007, tested it on cultured human hair follicles and on dermal papilla cells, the specialized fibroblasts at the base of the follicle: at picomolar to nanomolar concentrations it increased follicle elongation ex vivo and dermal papilla cell proliferation in vitro.
Data do not transfer between the two. Although they differ by one methyl group, each is a separate molecule, and results published for one describe that molecule only.
Mass and sequence.
The 14.03 g/mol gap between AHK and GHK, one CH2 group, is easy for mass spectrometry to resolve, so the identity test on a lab report tells them apart. Check the expected masses in the calculator, preloaded with AHK or GHK. The amino acid chart lists the alanine and glycine residues side by side.
GHK-Cu, tested by lot.
Helion does not supply AHK-Cu. It supplies GHK-Cu 50mg (CU50): lot CU501 tested at 99.92% HPLC purity at ILS Laboratories, with the report in the COA Portal, for laboratory research use only.
Specs and storage by compound.
Questions (8)
What are copper peptides?
Short peptides bound to a copper(II) ion. GHK-Cu, the copper complex of the plasma tripeptide glycyl-L-histidyl-L-lysine, is the best known; AHK-Cu is a synthetic analog.
Is GHK-Cu a copper peptide?
Yes. GHK-Cu is the original and most studied copper peptide: the tripeptide GHK with a bound copper(II) ion.
What is AHK-Cu?
The copper(II) complex of the tripeptide L-alanyl-L-histidyl-L-lysine (AHK), a synthetic analog of GHK with alanine in place of glycine.
What is the difference between AHK-Cu and GHK-Cu?
One amino acid: AHK starts with alanine, GHK with glycine. GHK is naturally occurring and widely studied; AHK-Cu has a much smaller literature.
Is AHK-Cu the same as GHK-Cu?
No. They are different molecules with different masses: the free tripeptides weigh 354.4 and 340.4 g/mol.
What is the molecular weight of AHK?
354.4 g/mol for the free tripeptide (C15H26N6O4); the copper complex is heavier.
How does GHK bind copper?
In solution, through the N-terminal amino group, the amide nitrogen between glycine and histidine, and histidine's imidazole ring, with a labile oxygen in the fourth position.
Does Helion sell AHK-Cu?
No. Helion supplies GHK-Cu 50mg (CU50) for laboratory research use only.
Published studies (4)
- The effect of tripeptide-copper complex on human hair growth in vitro
- X-ray and solution structures of Cu(II) GHK and Cu(II) DAHK complexes: influence on their redox properties
- Regenerative and Protective Actions of the GHK-Cu Peptide in the Light of the New Gene Data
- Glycyl-l-histidyl-l-lysine prevents copper- and zinc-induced protein aggregation and central nervous system cell death in vitro
Citations from PubMed for reference. They describe the compound in the literature, not any Helion lot, and nothing here is guidance on use.