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Molecular Weight
Purity
Storage
Appearance
Solubility
01
AHK-Cu is the copper(II) complex of the tripeptide L-alanyl-L-histidyl-L-lysine (AHK). It is a close structural relative of GHK-Cu: the two peptides are identical except at the first residue, where alanine takes the place of glycine.
That single extra methyl group sits right next to the N-terminal amine that anchors the copper ion, which makes AHK-Cu a useful partner compound for GHK-Cu. Comparing the pair shows how a small change near the binding site affects copper coordination, complex stability, chromatographic behaviour and redox properties. It is supplied as a lyophilized reference material for in vitro coordination chemistry, comparative metal-binding work and analytical method development.
02
AHK keeps the His-Lys portion of the GHK sequence unchanged, so the overall copper-binding pattern is expected to match that of GHK-Cu. The difference lies in the steric environment at the N-terminus.
Position 1: alanine vs glycine
Glycine has only a hydrogen as its side chain; alanine carries a methyl group. This adds a little bulk beside the N-terminal amine and creates a chiral centre at residue 1, which is absent in GHK.
Copper binding site
Copper is held by three nitrogen donors from the peptide: the N-terminal amine, the deprotonated Ala–His amide nitrogen and the histidine imidazole nitrogen, forming a roughly square-planar chelate. The lysine side-chain amine lies outside this primary chelate.
Mass relationship to GHK-Cu
The extra CH₂ makes AHK-Cu about 14 Da heavier than GHK-Cu (415.94 vs 401.91 g/mol), so the two are readily told apart by mass spectrometry.
03
Research use of AHK-Cu is largely comparative: it is studied alongside GHK-Cu to isolate the effect of one amino-acid change on copper chemistry.
Copper affinity
Potentiometric titration and isothermal titration calorimetry are used to measure and compare copper binding constants for AHK and GHK under the same conditions.
Copper exchange
Competition experiments with other ligands, such as EDTA, serum albumin or other peptides, show how readily copper is released or transferred from each complex.
Redox properties
Cyclic voltammetry compares the Cu(II)/Cu(I) potentials of the two complexes, showing how the coordination environment affects copper redox behaviour.
All characterisation described here is limited to solution chemistry and cell-free analytical systems.
04
Structure–property comparisons
Paired with GHK-Cu to study how the identity of residue 1 influences copper binding, geometry and redox behaviour.
Chromatographic selectivity
The alanine methyl group makes AHK-Cu slightly more hydrophobic, so it typically elutes after GHK-Cu in reversed-phase HPLC. The pair is useful for testing column selectivity and gradient design.
Speciation modelling
Included in titration series with GHK-Cu to build pH-dependent speciation models for copper–tripeptide systems.
Comparative stability testing
Run side by side with GHK-Cu under identical stress conditions to compare copper retention and degradation over time.
05
Storage
Store the lyophilized solid at −20 °C in a sealed, desiccated container away from light. Let the vial reach room temperature before opening to avoid condensation.
Visual check
The blue colour indicates intact copper coordination. Fading toward colourless suggests copper loss or decomposition.
pH
As with GHK-Cu, the complex weakens under acidic conditions as the histidine nitrogen is protonated, while strongly alkaline conditions favour copper hydroxide formation. Near-neutral, mildly buffered aqueous conditions are typical for analytical work.
Incompatibilities
Strong chelators such as EDTA remove copper from the peptide, and reducing agents (ascorbate, DTT, TCEP) reduce Cu(II) and destabilise the complex. Avoid both unless studying the free peptide.
Solutions
Prepare solutions fresh where possible. For short-term storage, aliquot and keep cold to limit freeze–thaw cycles.
06
AHK-Cu is analysed with the same metallopeptide methods used for GHK-Cu, with extra care when both are present in one sample.
HPLC
Reversed-phase C18 with an acidic mobile phase is standard. A shallow gradient usually separates AHK-Cu from GHK-Cu. Acidic conditions can partly dissociate the complex, so the peptide result is often read alongside copper content.
Mass spectrometry
ESI-MS shows the copper isotope doublet (two peaks 2 Da apart in roughly a 69:31 ratio). The 14 Da offset from GHK-Cu makes the two compounds easy to distinguish at standard resolution.
Copper content
The theoretical copper content of the 1:1 complex is about 15.3% by mass. Measured values are often lower because of counter-ions and residual water, so copper is usually confirmed by ICP or atomic absorption.
UV–visible spectroscopy
The broad visible absorption band responsible for the blue colour confirms copper coordination and can be compared directly with a GHK-Cu reference.
07
Only at the first amino acid: AHK-Cu has alanine where GHK-Cu has glycine. This adds a methyl group next to the copper-binding N-terminus, making AHK-Cu about 14 Da heavier and slightly more hydrophobic.
Yes. AHK-Cu is slightly more hydrophobic, so under the same reversed-phase conditions it usually elutes after GHK-Cu, and a shallow gradient generally separates the two.
Mass spectrometry shows the copper isotope doublet and a mass about 61.5 Da higher than free AHK. The blue colour and visible absorption band also confirm the copper is bound.
Usually by potentiometric titration or isothermal titration calorimetry, measuring both peptides under identical buffer, temperature and ionic-strength conditions so the values can be compared directly.
No. It is supplied strictly as a reference compound for laboratory and analytical research and is not for human or animal use.
AHK-Cu Research Reference. (2026). Pure Peptides Labs Research Catalogue. Retrieved from https://purepeptideslabs.net/research-catalogue/copper-peptides/ahk-cu/
Materials listed on this platform are supported by independent testing and published documentation for laboratory research contexts.
