GHK-Cu

GHK-Cu in brief

GHK-Cu is the copper(II) complex of the tripeptide glycyl-L-histidyl-L-lysine, first isolated from human serum in 1973 and listed as the cosmetic ingredient copper tripeptide-1. Copper sits in a square-planar site made from the glycine amine, the Gly-His amide nitrogen and a histidine imidazole nitrogen, leaving one equatorial position open to water or another ligand; calorimetry gave a conditional dissociation constant near 7 x 10^-14 M at pH 7.4. No receptor has been identified. Cell and animal work measured changes in collagen, glycosaminoglycan and metalloproteinase production, but which component acts is unsettled: copper alone reproduced one fibroblast response and copper-free GHK produced others. The supplied material's peptide-to-copper ratio and salt form are not stated.^{[1,2,3,4,5,6,7]}

GHK-Cu regulatory status

No FDA, EMA or Health Canada marketing authorisation was found for prezatide copper or for the complex under any of its names in Drugs@FDA (queried through openFDA), the EMA medicines database or the Health Canada Drug Product Database (searched November 2026); the highest phase reached in a registered trial is Phase 2, a recruiting vehicle-controlled study of a topical gel in healthy adults (NCT07437586). Its other public identity is as a cosmetic ingredient under the INCI name copper tripeptide-1. FDA lists GHK-Cu, for the parenteral route of administration named on its page, among bulk drug substances nominated for compounding whose nominations were withdrawn (page current as of 22 April 2026), stating that compounded drugs containing it may pose a risk of immunogenicity by that route because of the potential for aggregation and peptide-related impurities and that there are limited data in humans to inform safety-related considerations. The 2026 WADA Prohibited List does not name it.^{[8,9,10,11,7,12,13]}

GHK-Cu at a glance

• GHK-Cu is one Cu(II) ion held by the tripeptide Gly-His-Lys. In solution the copper is bound by three nitrogens of the peptide, leaving a fourth coordination site open to water or another ligand.^[2,14,15]
• The peptide binds Cu(II) tightly: isothermal titration calorimetry gave a conditional dissociation constant of about 7 x 10^-14 M at pH 7.4.^[3]
• GHK was isolated from human plasma in the 1970s and 1980 work found it co-purifying with roughly equimolar copper. The sequence also occurs inside collagen and the matrix protein SPARC, from which GHK-containing fragments can be released by proteolysis.^[1,4,16]
• Cell and animal work, much of it from two research groups in the 1980s and 1990s, measured changes in collagen, glycosaminoglycan and metalloproteinase production in fibroblast and rat wound-chamber systems. No receptor for GHK or GHK-Cu has been identified.^[4,17,18,5]

What is GHK-Cu?

GHK-Cu is a metal complex rather than a peptide on its own. The organic part is glycyl-L-histidyl-L-lysine, a tripeptide that Loren Pickart and colleagues purified from human plasma while studying a serum factor that altered the behaviour of cultured liver cells. When they isolated it, the peptide travelled through purification with approximately equimolar copper and a smaller amount of iron, which led them to propose that its biologically active form is a copper chelate. The dated steps run earlier than those 1980 papers: a growth-modulating tripeptide in human serum was reported in 1973, and identified as glycyl-histidyl-lysine in 1977. Neither record carries an abstract in PubMed, so each is cited for what its title states; note that the 1973 title says serum rather than the plasma albumin the compound is sometimes said to have come from.^{[19,1,20,6,21]}

Chemically it belongs to a family of short peptides that begin with an N-terminal amine followed by histidine (the 'Xxx-His' motif). Peptides of this class bind Cu(II) through three of their own atoms and need an external ligand to fill the fourth equatorial position. That separates GHK from the better known albumin-type motif (Xxx-Zzz-His, as in Asp-Ala-His-Lys), which wraps copper with four of its own nitrogens and exchanges the metal far more slowly.^[22,15,3]

The name is used loosely. 'GHK' sometimes means the copper-free peptide and sometimes the complex; registries also list a 2:1 bis-peptide copper species and several salt forms under related names such as prezatide copper and copper tripeptide-1. This page is about the 1:1 copper(II) complex. The copper-free peptide and the related tripeptide AHK-Cu are separate molecules. This library has no separate entry for the copper-free peptide, so it is described here; AHK-Cu has its own.^[23,7,24]

Its main public identity is not as a medicine. The compound is listed under the International Nomenclature of Cosmetic Ingredients name copper tripeptide-1, is registered in the FDA's substance system as prezatide copper with a DrugBank record, and no marketing authorisation was found for it under any of its names in the three medicines registers searched. The furthest it has reached in a registered trial is Phase 2. The regulatory section below carries the rest, including a compounding nomination that was withdrawn and the concern the agency stated when recording that.^{[7,23,8,9,10,11,12]}

GHK-Cu structure and sequence

The peptide is three residues long: glycine with a free amino terminus, L-histidine, and L-lysine ending in a free carboxylate. Copper(II) sits in a roughly square-planar site formed by the glycine amine, the nitrogen of the Gly-His amide bond (which loses its proton when copper binds) and a nitrogen of the histidine imidazole ring. Electron paramagnetic resonance (EPR) spectra first indicated two or three bound nitrogens and later showed the seven-line splitting expected for three, and electron spin-echo measurements place one of them in the imidazole. The lysine side chain is not part of the binding site at neutral pH; its amine stays protonated and joins the copper only under alkaline conditions.^[2,14,25]

Because one equatorial site is held only by water, GHK-Cu readily forms ternary complexes in which another molecule supplies the fourth ligand. Measured partners include histidine, glycine, imidazole, a second GHK molecule, cis-urocanic acid and histidine side chains on human serum albumin. Calculations reproduce the three-nitrogen-plus-one-oxygen arrangement and find the apical carboxylate contact to be the most mobile part of the site.^{[15,26,27,28,29]}

The registered formula of the neutral 1:1 complex is C14H22CuN6O4 (average mass 401.91 g/mol); the copper-free peptide is C14H24N6O4 (340.38 g/mol). There is no 3D view on this page: the free complex has small-molecule crystal structures but no Protein Data Bank entry, its solid-state form is a dimer that does not persist in solution, and the PDB entries that do contain copper-bound GHK use it as a tag fused to a larger protein.^[7,24,15,30]

Physically it is a strongly hydrophilic substance, and the properties that separate the complex from the free peptide in practice are stability ones. The single preformulation study of the complex measured octanol to phosphate-buffered-saline distribution coefficients between -2.38 and -2.49 across pH 4.5 to 7.4, which places it firmly in the water phase, and found it stable in water and in buffers over that pH range for at least two weeks at 60 degrees Celsius. Under stress it cleaves by hydrolysis, fastest under basic and oxidative conditions and more slowly under acid, with first-order profiles throughout; three degradation products were identified and one of them is free histidine, a constituent residue. It was compatible with Span 60 niosomes and less stable with the negatively charged lipid dicetyl phosphate. No water solubility figure is stated here: the one in circulation traces to a supplier safety data sheet rather than to a measurement that could be read.^[31,32]

Two stereocentres, both S: L-histidine and L-lysine (glycine is achiral). The SMILES is PubChem's ionic depiction (CID 165429100), with copper written as a separate Cu2+ ion beside a peptide carrying a deprotonated Gly-His amide nitrogen and carboxylate; it does not draw the metal-ligand bonds. In solution the complex is mononuclear, with three nitrogen donors in the equatorial plane. In the solid state it crystallises as a dimer or polymer in which carboxylate oxygens from neighbouring molecules complete the copper coordination, an arrangement shown not to persist in solution.^[23,2,15]

What studies on GHK-Cu show

Each card names the experimental system and what was measured. A result in one system is not evidence about another.

GHK-Cu compared with AHK-Cu and GHK-Cu + TB-500 + BPC-157

Four things about the 3 compounds most often read beside it, on axes that can be checked: what kind of substance it is, its formula and mass, what public records settle about which substance it is, and the strongest three-dimensional evidence that exists for it. Every figure is the one stated on that compound's own page, which is where it is cited, so the two can never disagree. The table compares no effect, no potency and nothing a compound has been reported to do, and these compounds are not alternatives to one another.

How GHK-Cu is studied as a copper(II) carrier

The longest-standing proposal is that GHK moves copper. The 1980 Nature report found the peptide co-isolated with copper, formed a complex readily and increased copper uptake into cultured hepatoma cells, and the authors noted that a histidine next to a basic residue resembles the copper-transport site of albumin. Equilibrium dialysis later showed that at equal concentrations GHK competes with albumin for Cu(II), taking about 42% of the copper, and that under plasma-like conditions about 6% of copper sits on low-molecular-weight ligands. Against this, an ESR study found no detectable adducts between the complex and Ehrlich ascites cells, which the authors read as consistent with poor uptake, and argued that a copper-histidine complex forms when GHK-Cu meets the cells.^[1,34,35]

Later coordination chemistry gave the open fourth site a central role. Because GHK leaves one equatorial position free, it forms ternary complexes with histidine, urocanic acid and albumin histidines, and it exchanges copper with other ligands quickly. Glutathione can bind that site and reduce the copper to Cu(I), which the authors propose as a route by which copper could reach the cellular importer CTR1. These are measurements in solution; none of them identifies a protein receptor for the complex.^{[15,26,27,29]}

A separate line of work treats GHK as a modulator of gene expression, from Connectivity Map queries in which GHK profiles opposed disease-associated signatures. Whether the peptide, the copper, or the complex is responsible is not settled: copper ions alone reproduced one fibroblast response, copper-free GHK produced effects in keratinocytes, and KGHK from SPARC acted without prior copper loading.^{[36,33,5,37,16]}

What is still unknown about GHK-Cu

Which component is active is the main open question. Some assays respond to copper alone, others to copper-free GHK, and in others the copper complex is required; a structure-activity study found the N-terminal glycine and the free lysine side chain mattered while the histidine could be replaced by synthetic residues. Many reports do not state whether 'GHK' was loaded with copper, so results for the peptide and the complex are often mixed in the literature. The 1994 SPARC work sharpens this from the other side: in an angiogenesis assay the activity of the GHK sequence was specific to the sequence and did not need bound copper, while a second copper-binding fragment of the same protein did nothing.^{[5,37,25,33,16]}

No receptor or binding protein with measured affinity has been described, so the cell-level findings lack a defined molecular target. Much of the fibroblast and rat wound-chamber evidence comes from one laboratory group in Reims, and the gene-expression arguments rest on Connectivity Map profiles from cancer cell lines rather than on targeted experiments. The most widely cited synthesis of this literature is a review written by the peptide's discoverer, which reads it favourably.^{[4,18,5,36,20]}

Speciation is also uncertain. The complex is fast-exchanging and forms 1:1, 2:1 and ternary species depending on concentration and partners, and its solid-state structure differs from its solution structure, so the form present in a given experiment or preparation is often not characterised. A preformulation study found the peptide stable in pH 4.5 to 7.4 buffers but cleaved under basic and oxidative stress, with histidine among the degradation products.^[15,26,31]

The one quantitative claim about the endogenous molecule could not be sourced. Readers meet a plasma level of about 200 nanograms per millilitre at age 20 falling to about 80 by age 60, and that pair of figures appears in review articles by the peptide's discoverer with no citation attached to the sentence that states them, and in an encyclopedia entry that attaches no reference either. Searches of PubMed and Europe PMC on 3 November 2026 returned no study that measured the peptide in human plasma by a stated method. The figures are therefore repeated here only as figures in circulation, and this page states no concentration of the peptide in plasma.^[38,32]

Key papers on GHK-Cu

1. Structure of the Glycyl-L-histidyl-L-lysine--copper(II) complex in solution.

   Freedman JH, Pickart L, Weinstein B, Mims WB, Peisach J (1982), Biochemistry · Spectroscopic structure study

   The solution-structure paper that defined the three-nitrogen copper site and showed the crystal form does not persist in solution.

2. X-ray and solution structures of Cu(II) GHK and Cu(II) DAHK complexes: influence on their redox properties.

   Hureau C, Eury H, Guillot R, Bijani C, Sayen S, Solari PL, Guillon E, Faller P, Dorlet P (2011), Chemistry · Structure and spectroscopy

   Crystal and solution structures side by side, with the comparison to the albumin-type DAHK site and the redox measurements.

3. Thermodynamic study of Cu2+ binding to the DAHK and GHK peptides by isothermal titration calorimetry (ITC) with the weaker competitor glycine.

   Trapaidze A, Hureau C, Bal W, Winterhalter M, Faller P (2012), J Biol Inorg Chem · Calorimetry

   The cleanest modern measurement of how tightly GHK binds Cu(II) at pH 7.4.

4. The interaction of copper(II) and glycyl-L-histidyl-L-lysine, a growth-modulating tripeptide from plasma.

   Lau SJ, Sarkar B (1981), Biochem J · Potentiometry and equilibrium dialysis

   Speciation and the equilibrium-dialysis competition with albumin that underpins the copper-transport idea.

5. Ternary Cu(2+) Complexes of Human Serum Albumin and Glycyl-l-histidyl-l-lysine.

   Bossak-Ahmad K, Bal W, Frączyk T, Drew SC (2021), Inorg Chem · Coordination chemistry

   Shows how Cu(GHK) and serum albumin form ternary complexes, and at which albumin histidines.

6. The tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu2+ stimulates matrix metalloproteinase-2 expression by fibroblast cultures.

   Siméon A, Emonard H, Hornebeck W, Maquart FX (2000), Life Sci · Cell assay

   A fibroblast experiment that tested the complex, the peptide and copper separately, which most studies did not.

7. A gene expression signature of emphysema-related lung destruction and its reversal by the tripeptide GHK.

   Campbell JD, McDonough JE, Zeskind JE, Hackett TL, et al. (2012), Genome Med · Expression profiling and cell assays

   The origin of the gene-expression line of work, with its computational basis stated openly.

8. Regenerative and Protective Actions of the GHK-Cu Peptide in the Light of the New Gene Data.

   Pickart L, Margolina A (2018), Int J Mol Sci · Review

   A full account of the history and gene-expression claims by the peptide's discoverer; read it as an advocate's review.

References

1. 1.Pickart L, Freedman JH, Loker WJ, Peisach J, Perkins CM, Stenkamp RE, Weinstein B. (1980). Growth-modulating plasma tripeptide may function by facilitating copper uptake into cells. Nature. 288:715-717. doi:10.1038/288715a0 · abstract only
2. 2.Freedman JH, Pickart L, Weinstein B, Mims WB, Peisach J. (1982). Structure of the Glycyl-L-histidyl-L-lysine--copper(II) complex in solution. Biochemistry. 21:4540-4544. doi:10.1021/bi00262a004 · abstract only
3. 3.Trapaidze A, Hureau C, Bal W, Winterhalter M, Faller P. (2012). Thermodynamic study of Cu2+ binding to the DAHK and GHK peptides by isothermal titration calorimetry (ITC) with the weaker competitor glycine. J Biol Inorg Chem. 17:37-47. doi:10.1007/s00775-011-0824-5 · abstract only
4. 4.Maquart FX, Pickart L, Laurent M, Gillery P, Monboisse JC, Borel JP. (1988). Stimulation of collagen synthesis in fibroblast cultures by the tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu2+. FEBS Lett. 238:343-346. doi:10.1016/0014-5793(88)80509-x · abstract only
5. 5.Siméon A, Emonard H, Hornebeck W, Maquart FX. (2000). The tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu2+ stimulates matrix metalloproteinase-2 expression by fibroblast cultures. Life Sci. 67:2257-2265. doi:10.1016/s0024-3205(00)00803-1 · abstract only
6. 6.Pickart L, Thaler MM. (1973). Tripeptide in human serum which prolongs survival of normal liver cells and stimulates growth in neoplastic liver. Nature New Biology. 243:85-7. PMID 4349963 · abstract only
7. 7.U.S. FDA Global Substance Registration System. PREZATIDE COPPER (UNII 6BJQ43T1I9). FDA GSRS. source · database record
8. 8.U.S. Food and Drug Administration. (2026). Drugs@FDA data, openFDA drugsfda endpoint, active-ingredient search for PREZATIDE and COPPER* (searched November 2026). openFDA. source · database record
9. 9.European Medicines Agency. (2026). Medicines data: all centrally processed human and veterinary medicines (JSON report), searched for prezatide copper and glycyl-histidyl-lysine, retrieved November 2026. European Medicines Agency. source · database record
10. 10.Health Canada. (2026). Drug Product Database, active ingredient search for glycyl and copper (searched November 2026). Health Canada Drug Product Database. source · database record
11. 11.ClinicalTrials.gov. (2026). NCT07437586: A Phase 2, randomized, double-blind, vehicle-controlled, split-wound study of topical GHK-Cu (copper(II)-peptide complex) gel in healthy adults, recruiting. ClinicalTrials.gov. source · database record
12. 12.U.S. Food and Drug Administration. (2026). Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks (Category 2 of the bulk substances nominated under sections 503A or 503B), content current as of 04/22/2026. U.S. Food and Drug Administration. source · full text read
13. 13.World Anti-Doping Agency. (2025). World Anti-Doping Code International Standard: Prohibited List 2026. World Anti-Doping Agency. source · full text read
14. 14.Laussac JP, Haran R, Sarkar B. (1983). N.m.r. and e.p.r. investigation of the interaction of copper(II) and glycyl-L-histidyl-L-lysine, a growth-modulating tripeptide from plasma. Biochem J. 209:533-539. doi:10.1042/bj2090533 · abstract only
15. 15.Hureau C, Eury H, Guillot R, Bijani C, Sayen S, Solari PL, Guillon E, Faller P, Dorlet P. (2011). X-ray and solution structures of Cu(II) GHK and Cu(II) DAHK complexes: influence on their redox properties. Chemistry. 17:10151-10160. doi:10.1002/chem.201100751 · abstract only
16. 16.Lane TF, Iruela-Arispe ML, Johnson RS, Sage EH. (1994). SPARC is a source of copper-binding peptides that stimulate angiogenesis. J Cell Biol. 125:929-943. doi:10.1083/jcb.125.4.929 · abstract only
17. 17.Wegrowski Y, Maquart FX, Borel JP. (1992). Stimulation of sulfated glycosaminoglycan synthesis by the tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu2+. Life Sci. 51:1049-1056. doi:10.1016/0024-3205(92)90504-i · abstract only
18. 18.Maquart FX, Bellon G, Chaqour B, Wegrowski J, Patt LM, Trachy RE, Monboisse JC, Chastang F, Birembaut P, Gillery P, et al. (1993). In vivo stimulation of connective tissue accumulation by the tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu2+ in rat experimental wounds. J Clin Invest. 92:2368-2376. doi:10.1172/JCI116842 · abstract only
19. 19.Pickart L, Thaler MM. (1980). Growth-modulating tripeptide (glycylhistidyllysine): association with copper and iron in plasma, and stimulation of adhesiveness and growth of hepatoma cells in culture by tripeptide-metal ion complexes. J Cell Physiol. 102:129-139. doi:10.1002/jcp.1041020205 · abstract only
20. 20.Pickart L, Margolina A. (2018). Regenerative and Protective Actions of the GHK-Cu Peptide in the Light of the New Gene Data. Int J Mol Sci. 19:1987. doi:10.3390/ijms19071987 · full text read
21. 21.Schlesinger DH, Pickart L, Thaler MM. (1977). Growth-modulating serum tripeptide is glycyl-histidyl-lysine. Experientia. 33:324-5. doi:10.1007/BF02002806 · abstract only
22. 22.Gonzalez P, Vileno B, Bossak K, El Khoury Y, Hellwig P, Bal W, Hureau C, Faller P. (2017). Cu(II) Binding to the Peptide Ala-His-His, a Chimera of the Canonical Cu(II)-Binding Motifs Xxx-His and Xxx-Zzz-His. Inorg Chem. 56:14870-14879. doi:10.1021/acs.inorgchem.7b01996 · abstract only
23. 23.National Center for Biotechnology Information. PubChem Compound records for copper(II) complexes of glycyl-L-histidyl-L-lysine (CID 71587328, Prezatide copper; CID 10111685; CID 165429100; CID 9831891, bis-prezatide copper). PubChem. source · database record
24. 24.National Center for Biotechnology Information. PubChem Compound record for glycyl-L-histidyl-L-lysine (CID 73587). PubChem. source · database record
25. 25.Conato C, Gavioli R, Guerrini R, Kozlowski H, Mlynarz P, Pasti C, Pulidori F, Remelli M. (2001). Copper complexes of glycyl-histidyl-lysine and two of its synthetic analogues: chemical behaviour and biological activity. Biochim Biophys Acta. 1526:199-210. doi:10.1016/s0304-4165(01)00127-1 · abstract only
26. 26.Bossak-Ahmad K, Wiśniewska MD, Bal W, Drew SC, Frączyk T. (2020). Ternary Cu(II) Complex with GHK Peptide and Cis-Urocanic Acid as a Potential Physiologically Functional Copper Chelate. Int J Mol Sci. 21:6190. doi:10.3390/ijms21176190 · full text read
27. 27.Bossak-Ahmad K, Bal W, Frączyk T, Drew SC. (2021). Ternary Cu(2+) Complexes of Human Serum Albumin and Glycyl-l-histidyl-l-lysine. Inorg Chem. 60:16927-16931. doi:10.1021/acs.inorgchem.1c03084 · abstract only
28. 28.Alshammari N, Platts JA. (2020). Theoretical study of copper binding to GHK peptide. Comput Biol Chem. 86:107265. doi:10.1016/j.compbiolchem.2020.107265 · abstract only
29. 29.Ufnalska I, Drew SC, Zhukov I, Szutkowski K, Wawrzyniak UE, Wróblewski W, Frączyk T, Bal W. (2021). Intermediate Cu(II)-Thiolate Species in the Reduction of Cu(II)GHK by Glutathione: A Handy Chelate for Biological Cu(II) Reduction. Inorg Chem. 60:18048-18057. doi:10.1021/acs.inorgchem.1c02669 · full text read
30. 30.Mehr A, Henneberg F, Chari A, Görlich D, Huyton T. (2020). The copper(II)-binding tripeptide GHK, a valuable crystallization and phasing tag for macromolecular crystallography. Acta Crystallogr D Struct Biol. 76:1222-1232. doi:10.1107/S2059798320013741 · full text read
31. 31.Badenhorst T, Svirskis D, Wu Z. (2016). Physicochemical characterization of native glycyl-l-histidyl-l-lysine tripeptide for wound healing and anti-aging: a preformulation study for dermal delivery. Pharm Dev Technol. 21:152-160. doi:10.3109/10837450.2014.979944 · abstract only
32. 32.Wikipedia contributors. Copper peptide GHK-Cu. Wikipedia. source · full text read
33. 33.Campbell JD, McDonough JE, Zeskind JE, Hackett TL, et al. (2012). A gene expression signature of emphysema-related lung destruction and its reversal by the tripeptide GHK. Genome Med. 4:67. doi:10.1186/gm367 · full text read
34. 34.Lau SJ, Sarkar B. (1981). The interaction of copper(II) and glycyl-L-histidyl-L-lysine, a growth-modulating tripeptide from plasma. Biochem J. 199:649-656. doi:10.1042/bj1990649 · abstract only
35. 35.Antholine WE, Petering DH, Pickart L. (1989). ESR studies of the interaction of copper(II)GHK, histidine, and Ehrlich cells. J Inorg Biochem. 35:215-224. doi:10.1016/0162-0134(89)84011-5 · abstract only
36. 36.Hong Y, Downey T, Eu KW, Koh PK, Cheah PY. (2010). A 'metastasis-prone' signature for early-stage mismatch-repair proficient sporadic colorectal cancer patients and its implications for possible therapeutics. Clin Exp Metastasis. 27:83-90. doi:10.1007/s10585-010-9305-4 · abstract only
37. 37.Choi HR, Kang YA, Ryoo SJ, Shin JW, Na JI, Huh CH, Park KC. (2012). Stem cell recovering effect of copper-free GHK in skin. J Pept Sci. 18:685-690. doi:10.1002/psc.2455 · abstract only
38. 38.Pickart L, Vasquez-Soltero JM, Margolina A. (2015). GHK Peptide as a Natural Modulator of Multiple Cellular Pathways in Skin Regeneration. BioMed Research International. 2015:648108. doi:10.1155/2015/648108 · full text read
39. 39.European Bioinformatics Institute. ChEBI 95185: 6-amino-2-[[2-[(2-amino-1-oxoethyl)amino]-3-(1H-imidazol-5-yl)-1-oxopropyl]amino]hexanoic acid. Chemical Entities of Biological Interest. source · database record Read through the EBI Ontology Lookup Service, because ChEBI's own web service answers 500. The returned name is the systematic form of Gly-His-Lys with no stereodescriptors, which is what this page says the record is, and the term is not marked obsolete.
40. 40.Royal Society of Chemistry. ChemSpider record 66263: Glycyl-L-histidyl-L-lysine, C14H24N6O4. ChemSpider. source · database record Read directly from the registry that issues the identifier, and the record's own title and formula were compared with the formula on this page. A bogus ChemSpider id answers 200 with the site's search page, so the record was confirmed by its content and not by its status code.
41. 41.Royal Society of Chemistry. ChemSpider record 335491: Glycylhistidyllysine - copper (1:1), C14H24CuN6O4. ChemSpider. source · database record Read directly from the registry. The record gives the 1:1 copper complex as C14H24CuN6O4, two hydrogens more than the C14H22CuN6O4 on this page, because this page describes the complex with the glycyl-histidine amide nitrogen deprotonated as it is when it coordinates the metal. The disagreement is a protonation state rather than a different substance, and it is stated here rather than reconciled silently.
42. 42.Mehr A, Henneberg F, Chari A, Görlich D, Huyton T. (2020). 6QUH: GHK tagged GFP variant crystal form II at 1.34A wavelength. RCSB Protein Data Bank. source · database record
43. 43.Ed (Edgar181). GHK Copper (chemical structure drawing). Wikimedia Commons. source · full text read