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Molecular Weight
Purity
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01
GHK-Cu (glycyl-L-histidyl-L-lysine copper(II) complex) is a metallopeptide in which the backbone Gly-His-Lys coordinates a divalent copper ion through a well-characterised multi-point binding geometry. First isolated from human plasma and subsequently synthesised for research use, GHK-Cu has a molecular weight of 403.93 g/mol and is registered under CAS number 49557-75-7. The copper coordination produces a distinctive blue to blue-green colour in the and concentrated solutions, providing a visual quality indicator.
As a metal- complex, GHK-Cu presents unique analytical requirements compared to standard organic peptides, including copper isotope pattern analysis, pH-dependent coordination , and metal-mediated redox chemistry. This material is supplied for controlled laboratory investigation of -metal interaction models, coordination chemistry studies, and chromatographic method development for metallopeptide species.
02
The coordination chemistry of GHK-Cu has been resolved by X-ray crystallography and solution-state NMR spectroscopy, revealing a square-planar Cu(II) binding geometry involving four nitrogen donors.
N-terminal amine (Gly1)
The primary amine of glycine provides the first coordination point, with deprotonation facilitated by the proximal copper ion.
Deprotonated amide nitrogen (Gly1-His2 bond)
Copper coordination promotes ionisation of the backbone amide, creating a strong equatorial donor.
Histidine imidazole Nπ (His2)
The imidazole ring nitrogen completes the three-nitrogen equatorial chelate, forming a particularly stable five-membered chelate ring.
Lysine amine (Lys3)
The ε-amino group of lysine may participate in axial coordination or remain protonated depending on pH and solution conditions.
This multi-point coordination produces a thermodynamically stable complex with a conditional constant (log K) of approximately 16.4 at physiological pH. The Cu(II) d⁹ electronic configuration generates characteristic d-d absorption bands near 600 nm, giving the complex its blue colour. For mass spectrometric purposes, the copper isotope pattern (63Cu at 69.2% and 65Cu at 30.8%, separated by 2 Da) provides an unambiguous diagnostic signature.
03
Laboratory research on GHK-Cu centres on the coordination chemistry and redox behaviour of the -metal complex rather than attributed biological mechanisms.
Copper coordination equilibria
Potentiometric titration studies characterise the pH-dependent speciation of GHK-Cu, mapping the transition from free and aqueous Cu2+ at low pH through mixed protonation states to the fully coordinated complex at neutral pH.
Redox cycling potential
Cu(II)/Cu(I) cycling within the framework is examined using cyclic voltammetry and electron paramagnetic resonance (EPR) spectroscopy. The redox potential of the coordinated copper is shifted relative to free aqueous copper, with implications for catalytic oxidation of nearby organic substrates.
Metallopeptide-protein interaction
In cell-free assays, GHK-Cu has been studied for its capacity to modulate collagen-related enzyme activities through copper donation or direct interaction. These studies characterise binding constants and kinetic parameters under defined conditions.
All mechanistic characterisation is confined to solution-phase analytical experiments and cell-free biochemical assays.
04
GHK-Cu is applied in laboratory settings that require metallopeptide reference standards and copper-coordination research models.
Metal-peptide speciation analysis
Potentiometric titration, UV-visible spectrophotometry, and EPR spectroscopy experiments use GHK-Cu to characterise copper- equilibria across pH ranges.
Chromatographic method development
GHK-Cu challenges standard reversed-phase methods due to potential copper interaction with silanol groups on the stationary phase. Method development focuses on mobile phase additives (EDTA, triethylamine) that suppress metal-silanophilic interactions while maintaining complex integrity.
Isotope pattern reference
The 63Cu/65Cu isotope doublet serves as a built-in mass calibration verification tool during LC-MS analysis of metallopeptide samples.
Oxidative stress model
In controlled degradation studies, GHK-Cu provides copper-mediated oxidation of co-formulated peptides (particularly methionine-containing sequences), serving as a model system for understanding metal-catalysed degradation.
All applications are confined to analytical chemistry and experimental contexts.
05
Storage:
-20°C, , desiccated. The blue-green colour of the intact complex provides a visual indicator; colour fading toward white suggests copper dissociation.
pH sensitivity:
Copper coordination is strongly pH-dependent. Below pH 4, protonation of the imidazole nitrogen weakens the chelate, and free Cu2+ ions may be released. Above pH 8, copper hydroxide precipitation becomes a competing process. Maintain reconstituted solutions between pH 4 and 6 for optimal complex .
Reconstitution:
Dissolve in mildly acidic water or acetate buffer (pH 5–6). Verify the characteristic blue colour persists in solution as confirmation of intact coordination. Colourless solutions indicate copper loss.
Redox sensitivity:
Cu(II) in the complex can be reduced to Cu(I) by common reducing agents (ascorbate, DTT, TCEP), dissociating the complex. Avoid reducing conditions during sample preparation.
Container selection:
Low-binding polypropylene tubes are essential. Glass containers may adsorb copper ions and alter the -to-metal stoichiometry. EDTA-treated glassware should be avoided as EDTA strips copper from the complex.
06
Metallopeptide analysis requires modified approaches compared to standard characterisation.
HPLC:
Reversed-phase C18 with 0.1% TFA provides acceptable separation, but copper-silanophilic interactions may cause peak tailing on older or highly active silica columns. End-capped, metal-free columns are preferred. Mobile phase supplementation with 0.05 mM EDTA suppresses secondary interactions but strips copper from the complex — use only when analysing the free .
Mass spectrometry:
ESI-MS in positive-ion mode yields a singly charged [M+H]+ ion with the diagnostic copper isotope pattern: two peaks separated by 2 Da with approximately 2.2:1 intensity ratio (63Cu:65Cu). This pattern distinguishes the intact metallopeptide from free GHK , which shows a standard carbon/nitrogen isotope envelope.
UV-Vis spectrophotometry:
The d-d transition band near 600 nm (molar absorptivity approximately 100 M⁻¹cm⁻¹) enables direct monitoring of copper coordination status. Loss of the 600 nm band indicates dissociation.
Purity assessment:
Evaluate both purity ( at 214 nm) and copper content (ICP-OES or atomic absorption) to confirm stoichiometric 1:1 -to-copper ratio. Free copper and free should each be below defined limits.
Analytical Data & Molecular Properties
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Materials listed on this platform are supported by independent testing and published documentation for laboratory research contexts.