GHK-Cu

1 Identity

Copper(II) coordination complex of an endogenous tripeptide ligand. A metal complex, not a peptide - which is why the panel is P5 and not P1. CAS 89030-95-5 for the 1:1 complex and 300801-03-0 for the mono-acetate (both commonly published). The metal-free parent is a separate record in this catalog: GHK, INCI tripeptide-1.

Sequence

Ligand: H-Gly-L-His-L-Lys-OH (GHK), all-L, free N-terminal amine, free C-terminal carboxylic acid, free lysine epsilon-amine. No amidation, no acetylation, no acylation, no PEGylation, no disulfide, no non-proteinogenic residue. The cataloged article is not the free tripeptide but its copper(II) coordination complex, conventionally written 1:1, in which Cu(II) is held by a three-nitrogen donor set - the N-terminal amine, the deprotonated Gly-His amide nitrogen and the histidine imidazole nitrogen - with the fourth equatorial position occupied by water or by a carboxylate oxygen donated by a neighboring complex. That solution-state description is well established. The solid actually shipped may be bridged, oligomeric, hydrated or salted, and that is established per lot by copper stoichiometry, counterion assay and mass balance rather than assumed. The metal is integral, not an impurity and not an additive: GHK and GHK-Cu are two different articles and this catalog holds two separate records for them.

Molecular formula

C14H22CuN6O4 (1:1 complex, free of added counterion). Free ligand C14H24N6O4. Mono-acetate salt C14H22CuN6O4 . C2H4O2 = C16H26CuN6O6.

Average mass

401.91 Da (C14H22CuN6O4). The formula gives 401.914 on IUPAC 2021 abridged conventional atomic weights, using the conventional atomic weight of copper 63.546, which is an isotope-weighted average and not the mass of any single molecule. Free GHK ligand 340.38 Da. Mono-acetate 461.97 Da (C16H26CuN6O6); one supplier's listing states FW 462.0 for that article, which is the same number. Theoretical copper content of the anhydrous unsalted complex 15.81 percent w/w (63.546 / 401.914).

Monoisotopic mass

401.0999 Da neutral for the 63Cu isotopologue; [M+H]+ 402.1072. Free GHK ligand 340.1859 neutral, [M+H]+ 341.1932. Mono-acetate 461.1210 neutral. The natural copper isotope envelope, 63Cu to 65Cu at 69.15 to 30.85, is part of the identity of this article and not an instrumental artifact: a monoisotopic figure quoted without stating which isotopologue it belongs to is incomplete, and the 65Cu isotopologue sits at 403.0980 neutral, 1.998 Da higher.

Salt / variant note

Six chemically distinct articles circulate under copper-tripeptide names and at least three of them are sold as 'GHK-Cu'. (1) Free GHK, C14H24N6O4, 340.38 / 340.186, CAS 49557-75-7 - no copper at all; the powder is white, not blue-violet; a separate record in this catalog. (2) 1:1 GHK-Cu, C14H22CuN6O4, 401.91 / 401.100 (63Cu), CAS 89030-95-5 - this record. (3) GHK-Cu mono-acetate, C16H26CuN6O6, 461.97 / 461.121, CAS 300801-03-0 - what the leading institutional supplier actually ships under the name GHK-Cu, so a quoted '462' is a salt mass and not a heavier complex. (4) Prezatide copper acetate, CAS 130120-57-9, C30H48CuN12O10, 800.33 / 799.291 - a 2:1 GHK:Cu bis-complex, a different stoichiometry entirely, and the INN-bearing article. (5) AHK-Cu, marketed as copper tripeptide-3: free ligand C15H26N6O4 354.41 / 354.202, complex C15H24CuN6O4 415.94 / 415.116, exactly +14.03 Da on this article - and at least one market reference publishes AHK-Cu under the page heading 'Copper Tripeptide-1', which is GHK-Cu's INCI name, so the two names are already crossed in print. (6) Palmitoyl tripeptide-1 (pal-GHK), C30H54N6O5, 578.80 / 578.416, the cosmetic raw material, +238.42 Da on the free ligand. Also arithmetically live: the bridged dimer [Cu2(GHK)2], C28H44Cu2N12O8, 803.83 / 802.200 (both 63Cu), a genuine solid-state species; N-acetyl-GHK C16H26N6O5 382.42 / 382.196; GHK amide C14H25N7O3 339.40 / 339.202; GHK acetate salt C16H28N6O6 400.44 / 400.207; and copper(II) acetate, 181.63, the spiking salt for a physical mixture of free GHK plus copper that passes ICP-MS and passes RP-HPLC and fails only the single-ion-series test. Finally, the 65Cu isotopologue of this article at 403.098 monoisotopic is not a variant at all but part of its natural envelope, and a certificate that reports it as a separate impurity has misread its own spectrum.

2 Class & testing panel

Form

Single article

Testing panel

P5 — panel definition

3 Primary sources & evidence

The index reports the design and provenance of the literature, not a conclusion about effect.

Published literature exists and is graded D for the topical file - animal and in-vitro evidence only. Identifiers carried in the source material, by study type: reviews and mechanism syntheses - Pickart L, Margolina A, Cosmetics 2015, DOI 10.3390/cosmetics2030236; peptide-chemistry and cell-based work - Choi HR et al., J Pept Sci 2012, DOI 10.1002/psc.2455; computational and structural work - Alshammari MK et al., Comput Biol Chem 2020, DOI 10.1016/j.compbiolchem.2020.107265; formulation, encapsulation and permeation methodology - Dymek M et al., Pharmaceutics 2023, DOI 10.3390/pharmaceutics15102485, and Ogorek et al., Molecules 2025, DOI 10.3390/molecules30010136, whose title asks whether the field is ready to measure skin permeation of the liposome-encapsulated complex at all. This substance is covered twice by design: a topical file and a separate systemic file in the healing-and-repair category, with the mechanism citations held in the latter and cross-referenced rather than restated. No adequately powered, independent, placebo-controlled human randomized controlled trial with biopsy-confirmed endpoints was located. Whether an intact copper complex reaches the dermis is recorded in the source material as an open methodological question rather than a settled value, and that is recorded here as a fact about the literature, not as a claim about anything else.

4 Storage & specification

Storage

Blue to blue-violet lyophilized or crystalline powder in a Type I amber glass vial with a PTFE-lined closure; a laboratory-chemical presentation, not a stoppered and crimped injection vial, with no sterility claim. Store at -20 degrees C plus or minus 5 degrees C, desiccated, tightly closed, protected from light. The color is the copper d-d absorption near 620-640 nm and is itself a first-line identity indicator, so any drift toward pale, green or brown is recorded and investigated rather than ignored. Hygroscopic; equilibrate the sealed vial to ambient temperature before opening so that moisture does not condense onto the cake. Keep physically segregated from the metal-free GHK record - separate shelf, separate weighing area, separate scoop - because cross-contamination in this pair runs in both directions and is invisible on an RP-HPLC trace. Avoid contact with strong chelators, reducing agents and phosphate buffers on reconstitution, all of which compete for or reduce the copper; the reconstitution diluent is stated on the label rather than left to the user. Reconstituted solution is aliquoted single-use and held at -80 degrees C. Ships ambient with a labeled cumulative excursion allowance and a single-use temperature logger in every export carton.

Shelf life

Provisional 24 months at -20 degrees C plus or minus 5 degrees C, desiccated and protected from light, from the date of QA release, stated as provisional pending the company's own stability data. Stability-indicating attributes are chosen for a metal complex rather than for a peptide: copper stoichiometry by ICP-MS, the UV-visible d-d band position and absorbance, free-ligand content (the decomplexation product, which is the characteristic degradation route), total related substances and Karl Fischer water. Real-time pulls at 3, 6, 9, 12, 18 and 24 months at the labeled condition plus 6 months accelerated at 40 degrees C / 75 percent relative humidity. Extension beyond 24 months only on real-time data from three commercial lots. Printed retest date on every vial and first-expiry-first-out enforced against that date rather than against receipt date; material passing retest is re-dated for a further 12 months, material failing is destroyed and the destruction is recorded.