GHK-Cu Molecular Weight, Sequence & CAS Reference

Overview of GHK-Cu (Glycyl-L-Histidyl-L-Lysine Copper Complex)

GHK-Cu is a naturally occurring tripeptide-copper complex consisting of L-glycyl-L-histidyl-L-lysine chelated with a divalent copper ion, Cu(II). Originally isolated from human plasma, GHK-Cu serves as a primary model in biomaterial, biochemical, and dermatological cell culture studies. Within our comprehensive catalog of research peptides, GHK-Cu represents one of the most thoroughly documented signaling peptides utilized in preclinical tissue architecture models.

As a high-affinity metal-binding peptide, the primary functional interest in GHK-Cu centers around its capability to deliver bio-available copper(II) ions to extracellular target sites. For high-throughput cell assays requiring exact stoichiometry, researchers utilize premium GHK-Cu reagent featuring validated purity profiles to maintain experimental reproducibility.

Amino Acid Sequence and Structural Topology

The primary amino acid sequence of the GHK peptide moiety is defined as Gly-His-Lys (single-letter code: GHK). In its structural orientation, the N-terminal glycine residue is linked to L-histidine, which connects to the C-terminal L-lysine residue via standard peptide bonds.

When complexed with copper, the coordination chemistry forms a square-planar geometry. The Cu(II) ion coordinates via the alpha-amino nitrogen of glycine, the peptide nitrogen of the glycine-histidine bond, the imidazole nitrogen of the histidine side chain, and an additional oxygen atom from a surrounding water molecule or buffer component. This specific spatial arrangement stabilizes the metal-peptide interface, protecting the copper ion from uncontrolled redox cycling in neutral aqueous solutions.

Molecular Formula and Mass Calculations

Accurate mass calculations are essential for quantitative analytical chemistry, high-performance liquid chromatography (HPLC), and mass spectrometry (MS) calibration. The molecular parameters of GHK vary depending on whether the molecule is evaluated in its free base uncomplexed form or as the copper-chelated salt.

Unbound GHK tripeptide has a molecular formula of C14H24N6O4 with a monoisotopic mass of 340.1859 Da and a average molecular weight of approximately 340.38 g/mol. Upon square-planar coordination with Cu(II) (copper atomic mass approx. 63.55 g/mol), two protons are lost from the ligand binding sites, resulting in the neutral complex formula C14H22CuN6O4.

The baseline formula weight for the neutral GHK-Cu complex is approximately 401.91 g/mol. However, commercial peptide synthesis commonly yields GHK-Cu as a salt (e.g., acetate or trifluoroacetate) with associated water molecules of hydration. Consequently, laboratory researchers must distinguish between the formula weight of the net complex and the total formula mass of the specific salt/hydrate form supplied.

CAS Registry Numbers and Chemical Identifiers

Chemical abstracts registry numbers provide distinct identification for regulatory compliance, safety datasheets (SDS), and material tracking. Because GHK can exist as a free peptide, a metal complex, or specific salt variations, multiple CAS numbers exist within chemical databases:

• GHK Free Tripeptide CAS: 49557-75-7 • GHK-Cu Complex (Glycyl-L-histidyl-L-lysine copper derivative) CAS: 89030-95-5 • GHK-Cu Acetate Salt CAS: 13039-35-5 / 89030-95-5 (context dependent)

When cross-referencing literature or ordering analytical standards, referencing CAS 89030-95-5 explicitly targets the divalent copper-chelated tripeptide entity. Chemical IUPAC nomenclature designates the molecule as copper(2+);(2S)-6-amino-2-[[(2S)-2-[(2-aminoacetyl)amino]-3-(1H-imidazol-5-yl)propanoyl]amino]hexanoate.

Salt Form Variations: Acetate vs. TFA Counter-Ions

Peptides manufactured via solid-phase peptide synthesis (SPPS) undergo cleavage and purification processes that introduce counter-ions to balance basic residues (such as the lysine side chain and histidine imidazole in GHK). The two most common counter-ion forms are Trifluoroacetate (TFA) and Acetate.

TFA salts retain strong ionic interactions with basic amino acids, yielding high stability but potentially interfering with sensitive cellular assays if counter-ion concentration is not controlled. Acetate salts replace TFA with acetic acid molecules, which is often preferred for cell culture models to minimize background cytotoxicity.

The choice of salt form directly impacts the Gross Molecular Mass of the delivered product. A vial containing 50 mg of gross GHK-Cu acetate salt will contain a lower mass of actual net peptide complex compared to pure free base calculations. Researchers must account for counter-ion content and moisture (hydration factor) when preparing exact millimolar working concentrations.

Calculating Net Peptide Content and Assay Preparation

Net Peptide Content (NPC) represents the actual percentage of the vial weight comprised of the targeted peptide sequence, excluding moisture and counter-ions (acetate or TFA). For instance, if an HPLC/MS analysis indicates an NPC of 84.5%, a 10 mg lyophilized cake contains 8.45 mg of active GHK-Cu complex.

To achieve accurate laboratory dilutions, researchers should use the lot-specific NPC value alongside our automated peptide reconstitution calculator. Correct concentration calculations ensure that molarity calculations in cell culture or enzyme inhibition assays reflect true ligand density rather than total salt weight.

Preclinical Research Applications and Biological Mechanisms

In preclinical model systems, GHK-Cu is widely studied for its tissue remodeling and regenerative properties. Research indicates that the GHK-Cu complex plays a key role in modulating extracellular matrix (ECM) synthesis and turnover.

In vitro data suggest that GHK-Cu stimulates the expression of messenger RNA for collagen types I and III, as well as elastin and glycosaminoglycans. Rodent and cell culture models demonstrate that GHK-Cu promotes accelerated wound closure, enhances dermal fibroblast proliferation, and regulates matrix metalloproteinase (MMP) secretion. Through these pathways, GHK-Cu is frequently researched for its potential to facilitate structured skin remodeling while reducing fibrotic scarring during tissue repair phases. Review broader mechanistic analyses in our preclinical research database.

Comparative Analysis: GHK-Cu and Related Remodeling Compounds

To contextualize GHK-Cu within experimental frameworks, researchers frequently compare its biochemical parameters against related remodeling peptides and metal-binding analogues. The uncomplexed unbound GHK sequence lacks the specific square-planar Cu(II) donor platform, exhibiting different binding kinetics and lower thermal stability in aqueous media.

Similarly, AHK-Cu copper peptide replaces the N-terminal glycine with alanine (Ala-His-Lys-Cu), altering lipophilicity and target receptor affinity in hair follicle cell lines. For lipid-encapsulated assays, lipophilic modifications like Pal-GHK lipopeptide attach a palmitoyl chain to the N-terminus, altering cell membrane permeability while removing direct copper-chelation dynamics. Understanding these structural variations allows researchers to select the precise peptide candidate for their specific assay target.

Analytical Verification via HPLC and Mass Spectrometry

Ensuring structural integrity and salt ratio accuracy requires rigorous analytical verification. At PX1 Research, every production lot undergoes High-Performance Liquid Chromatography (HPLC) to establish purity levels (typically >=98%) and Matrix-Assisted Laser Desorption/Ionization (MALDI-TOF) or ESI Mass Spectrometry to verify exact molecular weight.

In addition to sequence mass confirmation, raw materials are subjected to quantitative bacterial endotoxin testing (LAL assay) to guarantee suitability for sensitive cell culture environments. Researchers can access batch-specific chromatograms and mass spectra directly through our online lot-specific certificate of analysis portal.

Laboratory Storage, Handling, and Stability Protocols

Lyophilized GHK-Cu powder exhibits high physical stability when stored at -20°C in a desiccated environment protected from light. Due to the hygroscopic nature of peptide salts, vials should be allowed to equilibrate to room temperature prior to opening to prevent atmospheric moisture condensation.

Upon reconstitution in sterile bacteriostatic water or phosphate-buffered saline (PBS, pH 7.4), GHK-Cu solutions remain stable at 4°C for short-term experimental series (typically 2–4 weeks). For long-term storage of aliquots, -80°C is recommended. Avoid strong chelating agents (such as EDTA) in buffer formulations, as they will compete with the tripeptide for Cu(II) binding, causing premature dissociation of the complex. Laboratories requiring large-scale batching for automated platforms can request custom preparations through our bulk research quantities division.