Copper peptide comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Updated 2026-01-08. Numbers and descriptions here follow the published literature rather than marketing material.
Published studies describe the complex in several research contexts, including collagen synthesis, antioxidant behaviour, and wound repair models. Much of this work is conducted in cultured cells or in small animal systems, and the findings are frequently cited in reviews of copper peptides. Direct clinical evidence in humans is comparatively limited, and reported outcomes vary with formulation and study design. Whether free chain or metal-bound form was used is not always stated, a point that complicates comparison between reports.
GHK-Cu is a coordination complex formed between the peptide glycyl-L-histidyl-L-lysine and a copper(II) ion. The unbound chain, abbreviated GHK, consists of three amino acids and occurs naturally in human plasma, saliva, and urine. Binding of the metal is mediated mainly by the imidazole nitrogen of the histidine residue together with backbone amides, producing a stable chelate. Ingredient nomenclature often lists the same substance as copper tripeptide-1. Its charge and solubility behaviour differ from those of the metal-free chain.
The peptide was first isolated from human albumin in 1973 by Loren Pickart, who later described its copper-binding behavior. Early work linked the complex to wound healing and tissue remodeling. Plasma levels of GHK decline with age, a pattern that stimulated interest in topical and supplemental applications. Researchers have reported that the tripeptide influences collagen synthesis, antioxidant defense, and inflammatory signaling in cell and animal models. Human clinical evidence remains limited and often relies on small studies.
Commercial products list GHK-Cu as copper tripeptide-1, a cosmetic ingredient. Formulators value its blue color and water solubility, which allow incorporation into serums, creams, and masks. Regulatory treatment varies: in the United States it appears in cosmetics, while some jurisdictions classify certain claims as drug-like. The compound is not an approved drug for any indication. Studies continue to examine its effects on skin, hair, and wound repair, but dosage, delivery, and long-term safety questions remain open.
GHK-Cu is a coordination complex formed between the tripeptide glycyl-L-histidyl-L-lysine and copper(II). The peptide sequence consists of glycine, histidine, and lysine, and its imidazole and amino groups provide binding sites for the metal ion. In the complex, copper is held through nitrogen donors from the histidine side chain, the N-terminal amine, and deprotonated amide nitrogens. The resulting compound is intensely blue and water-soluble. It occurs naturally in human plasma, saliva, and urine at low concentrations.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Copper(II) peptide complex | Coordination compound rather than a simple salt |
| Peptide sequence | Glycyl-L-histidyl-L-lysine | Abbreviated GHK in most literature |
| Molecular formula | C14H22N6O4Cu | Reported for the 1:1 complex |
| Principal binding site | Histidine imidazole nitrogen | Backbone amides contribute additional coordination |
| Common synonym | Copper tripeptide-1 | Used in ingredient and product labelling |
Identity and purity are assessed mainly by reversed-phase high-performance liquid chromatography with ultraviolet detection, often paired with mass spectrometry to confirm the expected mass. Copper content is measured separately by inductively coupled plasma optical emission spectrometry or atomic absorption spectroscopy, because the peptide assay alone does not establish the metal-to-peptide ratio. Visible spectroscopy provides a rapid check on complex integrity through the absorption band in the visible region. Agreement between the peptide assay and the copper assay is the practical test of whether a sample is the intended complex rather than a mixture.
Aqueous solutions of GHK-Cu are less stable than the dry powder. The peptide backbone is vulnerable to hydrolysis at extreme pH, and copper can be stripped from the complex by strong chelating agents such as EDTA or citrate. Oxidising agents and high concentrations of ascorbic acid can reduce copper(II) and change the complex, which is one reason formulators often keep such ingredients in separate phases. How quickly these changes occur under real storage conditions depends on pH, buffer, temperature and packaging, and quantitative data on the subject are limited.
Identity and purity are established with a combination of chromatographic and spectroscopic techniques. Reversed-phase high-performance liquid chromatography separates the intact complex from peptide fragments and free copper, and the elution profile yields a purity estimate. Mass spectrometry gives the mass of the intact species and exposes degradation products. Ultraviolet-visible spectroscopy displays a broad absorption band in the visible region that is characteristic of the copper center. Nuclear magnetic resonance is less informative here, because the paramagnetic metal broadens signals and complicates spectral interpretation.
Copper content is measured separately, since a peptide assay alone does not report the metal-to-peptide ratio. Elemental techniques such as inductively coupled plasma optical emission spectroscopy quantify copper after acid digestion of the sample. The result is compared with the theoretical value for a one-to-one complex, and a shortfall indicates free peptide or partial dissociation. Suppliers differ in how they state purity, as some quote peptide content and others quote the whole complex. A defined stoichiometry therefore requires both a peptide assay and a copper assay.
The International Nomenclature of Cosmetic Ingredients lists the substance as copper tripeptide-1, the name that appears on most topical product labels. Related designations include copper peptide and GHK-Cu, and the hyphenated form is common in research literature. In cosmetics the material is regulated as an ingredient rather than as a drug, so products may reach the market without evidence of the effects claimed for them. Whether those effects are clinically meaningful is an open question, since most supportive data come from laboratory work and small trials.
GHK-Cu is the copper complex of the tripeptide glycyl-L-histidyl-L-lysine, a short sequence found naturally in human plasma, saliva and urine. Loren Pickart reported the isolation of the free peptide in 1973 while studying factors that influenced the growth of aged liver cells in culture. The peptide was later shown to bind copper(II) with high affinity, and the metal-bound form became the focus of most subsequent research. Its concentration in circulation declines markedly with age, a pattern that is well documented, though the physiological consequences of that decline remain debated.
Having returned to the throne and consolidated his power, the Bourbon king unified the two kingdoms he ruled. With the law of 16 December 1816, the Kingdom of the Two Sicilies was born, with Ferdinand as its first monarch, dubbedFerdinand I of the Two Sicilies.
== External links == Official website of Lotte Bjerre Knudsen An unofficial source listing the publications of Knudsen. A formal source of patents issued to Knudsen. The 2022 Danish TV mini-series, "The Story of GLP-1", focused on the work of Knudsen.
== History == In 1844, Theodor Wertheim separated by steam distillation a pungent-smelling substance from garlic and named it "allyl sulfur." However, only in 1892 could Friedrich Wilhelm Semmler identify diallyl disulfide as one of the components of distilled garlic oil. The natural precursor of diallyl disulfide, allicin, was discovered in 1944 by Chester J. Cavallito and John Hays Bailey. In 1947, A. Stoll and E. Seebeck found that allicin in turn can be produced from the cysteine derivative alliin using the enzyme alliinase.
The Valley Library Special Collections at Oregon State University contain the Ava Helen and Linus Pauling Papers, including digitized versions of Pauling's forty-six research notebooks. In 1986, Caltech commemorated Linus Pauling with a symposium and lectureship. The Pauling Lecture series at Caltech began in 1989 with a lecture by Pauling himself. The Caltech Chemistry Department renamed room 22 of Gates Hall the Linus Pauling Lecture Hall, since Pauling spent so much time there. Other places named after Pauling include Pauling Street in Foothill Ranch, California; Linus Pauling Drive in Hercules, California; Linus and Ava Helen Pauling Hall at Soka University of America in Aliso Viejo, California; Linus Pauling Middle School in Corvallis, Oregon; and Pauling Field, a small airfield located in Condon, Oregon, where Pauling spent his youth. There is a psychedelic rock band in Houston, Texas, named The Linus Pauling Quartet. The asteroid 4674 Pauling in the inner asteroid belt, discovered by Eleanor F. Helin, was named after Linus Pauling in 1991, on his 90th birthday. Linus Torvalds, developer of the Linux kernel, and Linus Sebastian, YouTuber known for the technology-oriented channel Linus Tech Tips, are named after Pauling. Nobel laureate Peter Agre has said that Linus Pauling inspired him. In 2010, Pacific Northwest National Laboratory named its distinguished postdoctoral program in his honor, as the Linus Pauling Distinguished Postdoctoral Fellowship Program.
Sources: en.wikipedia.org
== Genetics == The biologic instructions for synthesising protein C in humans are encoded in the gene officially named "protein C (inactivator of coagulation factors Va and VIIIa)". The gene's symbol approved by the HUGO Gene Nomenclature Committee is "PROC" from "protein C". It is located on the second chromosome (2q13-q14) and comprises nine exons. The nucleotide sequence that codes for human protein C is approximately 11,000 bases long.
=== Thermoresponsivity in water === Polymer solutions that show thermoresponsivity in water are especially important since water as a solvent is cheap, safe and biologically relevant. Current research efforts focus on water-based applications like drug delivery systems, tissue engineering, bioseparation (see the section Applications). Numerous polymers with LCST in water are known. The most studied polymer is poly(N-isopropylacrylamide). Further examples are poly[2-(dimethylamino)ethyl methacrylate] (pDMAEMA) hydroxypropylcellulose, poly(vinylcaprolactam), poly-2-isopropyl-2-oxazoline and polyvinyl methyl ether. Some industrially relevant polymers show LCST as well as UCST behavior whereas the UCST is found outside the 0-to-100 °C region and can only be observed under extreme experimental conditions. Examples are polyethylene oxide, polyvinylmethylether and polyhydroxyethylmethacrylate. There are also polymers that exhibit UCST behavior between 0 and 100 °C. However, there are large differences concerning the ionic strength at which UCST behavior is detected. Some zwitterionic polymers show UCST behavior in pure water and also in salt-containing water or even at higher salt concentration. By contrast, polyacrylic acid displays UCST behavior solely at high ionic strength. Examples for polymer that show UCST behavior in pure water as well as under physiological conditions are poly(N-acryloylglycinamide), ureido-functionalized polymers, copolymers from N-vinylimidazole and 1-vinyl-2-(hydroxylmethyl)imidazole or copolymers from acrylamide and acrylonitrile.
When the analytical concentration of methylamine is twice that of ethylenediamine and the concentration of copper is the same in both reactions, the concentration [Cu(en)]2+ is much higher than the concentration [Cu(MeNH2)2]2+ because β11 ≫ β12. The difference between the two stability constants is mainly due to the difference in the standard entropy change, ΔS⊖. In the reaction with the chelating ligand there are two particles on the left and one on the right, whereas in equation with the monodentate ligand there are three particles on the left and one on the right. This means that less entropy of disorder is lost when the chelate complex is formed than when the complex with monodentate ligands is formed. This is one of the factors contributing to the entropy difference. Other factors include solvation changes and ring formation. Some experimental data to illustrate the effect are shown in the following table.
=== Acid-base behavior === The acid dissociation constant (pKa) values of all alkanes are estimated to range from 50 to 70, depending on the extrapolation method, hence they are extremely weak acids that are practically inert to bases (see: carbon acids). They are also extremely weak bases, undergoing no observable protonation in pure sulfuric acid (H0 ~ −12), although superacids that are at least millions of times stronger have been known to protonate them to give hypercoordinate alkanium ions (see: methanium ion). Thus, a mixture of antimony pentafluoride (SbF5) and fluorosulfonic acid (HSO3F), called magic acid, can protonate alkanes.
=== 2025–present === In February 2026, before an upcoming US–Brazil meeting, the Brazilian president Luiz Inácio Lula da Silva told a news conference in New Delhi that Brazil wants neither "a new Cold War" nor any country's intervention but rather be "treated equally" like all other countries. He declared this a message to the second administration of Donald Trump, who became the US president again in 2025, succeeding Biden.
Sources: en.wikipedia.org
GHK denotes the unbound chain of three amino acids. GHK-Cu describes the form in which a copper(II) ion is held by that chain. The two are not interchangeable in solution, since charge, molecular weight, and reactivity differ.
The chain occurs in human plasma, saliva, and urine. Measured amounts are reported to fall with age. Copper binding by the sequence is treated as part of normal metal handling in tissue.
The bound copper(II) centre contributes to redox behaviour and to stability under physiological conditions. Free copper ions can participate in reactions that generate reactive species, while chelated metal is generally more controlled. The chain may also serve as a carrier for copper in experimental systems.
GHK is the free tripeptide, while GHK-Cu includes a bound copper(II) ion. The copper complex is the form most often studied for skin and wound-related activity. The two names are sometimes used interchangeably in product labeling, but they refer to distinct chemical species.