The short version of metal chelation fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-06-26 and is reviewed periodically as new material appears.
The sequence carries three residues in the order glycine, histidine, lysine, which places a small, flexible chain around a single metal centre. Compared with larger copper-binding proteins, the complex is compact and its coordination chemistry can be reproduced with synthetic peptide in a laboratory. Published structural work agrees on the nitrogen donor set but differs in the exact geometry assigned under some conditions, so the arrangement is best treated as well characterised in outline rather than fixed in every detail.
GHK-Cu is a coordination complex formed between the tripeptide glycyl-L-histidyl-L-lysine and a copper(II) ion. The peptide was isolated from human plasma in the early 1970s by Loren Pickart, who observed that a plasma fraction from young donors stimulated growth in cultured liver cells. The copper-bound form is abbreviated GHK-Cu, while the metal-free peptide is written simply as GHK. In the research literature the complex also appears as copper tripeptide-1 and as glycyl-histidyl-lysine copper complex.
Copper(II) binds the peptide through four nitrogen donors: the terminal amino group, the imidazole nitrogen of histidine, and two deprotonated amide nitrogens of the peptide backbone. This tetradentate arrangement gives a roughly square-planar geometry, the thermodynamically favoured form near neutral pH. Because the amide nitrogens must lose a proton before they can coordinate, complex formation is strongly pH-dependent, and the fully coordinated species dominates only above mildly acidic conditions. Electronic transitions within the copper d orbital set produce the characteristic blue to violet colour in aqueous solution.
Analytical confirmation usually combines a separation method with a copper-specific measurement. Liquid chromatography or mass spectrometry establishes peptide identity and purity, while an elemental measurement quantifies the metal content. A frequent misconception is that any blue solution contains an intact copper peptide complex; color alone does not confirm structure, because free copper salts and degraded mixtures can also appear colored. Literature on efficacy is mixed, with in vitro findings often more dramatic than human evidence, and reviews note small sample sizes and short follow-up. Open questions include optimal concentration, skin penetration, and long-term effects.
Proposed mechanisms for copper peptide activity center on delivery of copper ions to cells and on peptide fragments acting as signaling molecules. Copper is a cofactor for enzymes involved in collagen cross-linking and antioxidant defense, and the peptide may improve its availability at target sites. Separately, the tripeptide and its breakdown products have been reported to influence gene expression in cultured fibroblasts. Much of this evidence comes from laboratory cell cultures and animal models rather than controlled human trials. The relative contribution of the copper ion and the peptide sequence is therefore not fully settled.
Stability depends on temperature, light exposure, moisture, and the presence of oxidizing or reducing agents. Solid material held dry and protected from light is generally more stable than aqueous solutions, which can undergo gradual degradation. Recommended storage in much of the literature is a freezer at around minus twenty degrees Celsius for long-term retention, with working aliquots kept cold and shielded from light. Repeated freeze-thaw cycles and alkaline pH are commonly noted as factors that accelerate loss of the intact complex, though exact degradation rates vary.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Copper(II)-tripeptide complex | One peptide ligand with one coordinated metal centre |
| Peptide sequence | Gly-His-Lys | Three residues written in one-letter notation |
| Free peptide mass | 340.4 g/mol | Metal-free GHK; the complex has a higher mass |
| Appearance | Blue to violet solid or solution | Colour originates from copper d orbital transitions |
| Storage | Desiccated, -20 °C, protected from light | Dry powder is more stable than dissolved material |
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.
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.
Discovery of GHK is generally attributed to work in the 1970s that isolated a plasma factor influencing liver cell behavior. Subsequent studies identified the copper-binding tripeptide and its ability to chelate copper with high affinity. Early reports linked the complex to wound healing and tissue remodeling in animal models. The free peptide and the copper-bound form have different properties, so the two are distinguished in the literature. Whether endogenous GHK-Cu serves a single primary physiological role remains an open question.
The molecular weight and charge of GHK-Cu depend on the pH and the number of coordinated ligands. At neutral pH, the peptide typically binds one copper ion, but ternary complexes with other biomolecules can form. Spectroscopic methods such as electron paramagnetic resonance and circular dichroism are used to study the coordination environment. Reports on the exact geometry vary because the complex is dynamic in solution. Researchers often use synthetic GHK-Cu rather than extracted material to control stoichiometry and purity.
GHK-Cu is a coordination complex formed from the tripeptide glycyl-L-histidyl-L-lysine and a copper(II) ion. The peptide binds copper through its histidine imidazole nitrogen, the terminal amino group, and the deprotonated amide nitrogen. This arrangement creates a square-planar or distorted geometry around the metal center, depending on pH and the presence of competing ligands. The complex occurs naturally in human plasma, saliva, and urine at low concentrations, and its sequence is conserved across many vertebrate species.
Material described as GHK-Cu appears in several distinct markets, including cosmetic ingredients, laboratory reagents, and consumer products, and the quality expectations attached to each differ. A certificate of analysis generally reports peptide purity by chromatography, copper content, appearance, and residual solvents or counterions. Counterion identity matters, because the complex is usually supplied as an acetate or a similar salt, and the counterion contributes to the measured mass. Independent verification of sequence and metal stoichiometry is advisable when a material is used for quantitative work. Batch-to-batch variation is common and should be documented rather than assumed negligible.
Copper peptide solutions tend to resist degradation better than many free peptides, because the bound metal protects the N-terminus and reduces susceptibility to some peptidases. Backbone hydrolysis, oxidation of the histidine imidazole ring, and photochemical reactions remain the principal degradation routes. Aqueous solutions are generally most stable near neutral to mildly acidic pH, while strongly alkaline conditions accelerate hydrolysis. Light exposure is usually avoided, since both the peptide and the copper center can take part in photochemical processes. Stability data published by suppliers often describe short-term behavior rather than multi-year shelf life.
The peptide sequence places a histidine in the middle, and this residue dominates metal binding. Copper(II) coordinates through the imidazole nitrogen of histidine and the terminal amino group, forming a stable chelate ring system. Loss of the copper ion leaves the free tripeptide, which has different solubility and reactivity. This structural detail matters because assays that measure only the peptide backbone can miss whether copper is still bound to it.
Several names circulate for the same material, which complicates literature searches. Cosmetic ingredient lists often use copper tripeptide-1, while older biochemistry papers use glycyl-L-histidyl-lysine or its abbreviation GHK. The copper complex is sometimes written as GHK-Cu(II) to make the oxidation state explicit. Terminology is not fully standardized, so matching a compound across sources requires attention to the exact sequence, the counterion, and the stated copper content. Reviews that compare studies must account for these naming differences before drawing conclusions.
=== Retesting of samples === According to Article 6.5 in the World Anti-Doping Code samples may be retested later. Samples from high-profile events, such as the Olympic Games, are now retested up to eight years later to take advantage of new techniques for detecting banned substances.
=== Wine laws and regulations === In the United States, the Alcohol and Tobacco Tax and Trade Bureau (TTB) limits the use of diammonium phosphate as a nitrogen additive to 968 mg/L (8 lbs/1000 gal) which provides 203 mg N/L of YAN. In the European Union, most countries follow the guidelines of the International Organisation of Vine and Wine (OIV) which dictates a limit of 300 mg/L. In Australia, the limit is based on the level of inorganic phosphate with a maximum limit of 400 mg/L of phosphate permitted.
Muammar Muhammad Abu Minyar al-Gaddafi (c. 1942 – 20 October 2011) was a Libyan military officer, revolutionary, politician, and political theorist who ruled Libya from 1969 until his overthrow by Libyan rebel forces in 2011 during the First Libyan Civil War. He came to power through a bloodless military coup, first becoming Revolutionary Chairman of the Libyan Arab Republic from 1969 to 1977, Secretary General of the General People's Congress from 1977 to 1979, and then the Brotherly Leader of the Great Socialist People's Libyan Arab Jamahiriya from 1979 to 2011. Initially ideologically committed to Arab nationalism and Arab socialism, Gaddafi later ruled according to his own Third International Theory. Gaddafi became an Arab nationalist while at school in Sabha, later enrolling in the Royal Military Academy, Benghazi. He founded a revolutionary group known as the Free Officers movement which deposed the Western-backed Senussi monarchy of Idris I in a 1969 coup. Gaddafi converted Libya into a republic governed by his Revolutionary Command Council. Ruling by decree, he deported Libya's Italian population and ejected its Western military bases. He strengthened ties to Arab nationalist governments and unsuccessfully advocated pan-Arab political union. An Islamic modernist, he introduced Sharia law and promoted Islamic socialism. He nationalized the oil industry and used the increasing state revenues to bolster the military, fund foreign revolutionaries, and implement social programs emphasizing housebuilding, healthcare and education projects.
=== Che–Cl === Zhijian James Chen (b. 1966). Chinese-American biochemist at the University of Texas Southwestern Medical Center, known discovering mechanisms by which nucleic acids trigger innate and autoimmune responses from the interior of a cell. Member Natl. Acad. Sci. USA. Albert Chibnall FRS (1894–1988), British biochemist known for his work on the nitrogen metabolism of plants. Ruth Chiquet-Ehrismann (1954–2015), Swiss biochemist and cell biologist working on interactions in the extracellular matrix. Cyrus Chothia FRS (1942–2019). British biochemist at Cambridge known for work on protein structure. Gilbert Chu (b. 1946). American biochemist at Stanford, known for investigating how cells react to DNA damage from radiation. George M. Church (b. 1954). American geneticist at Harvard and MIT, known for pioneering personal genomics and synthetic biology. Member Natl. Acad. Sci. USA. Aaron Ciechanover (b. 1947). Israeli biochemist at the Technion, Haifa, known for work on protein turnover. Nobel Prize for Chemistry in 2004. Foreign associate Natl. Acad. Sci. USA. Vintilă Ciocâlteu (1890–1947) Roumanian physician, biochemist, researcher, professor, and author. Hans Thacher Clarke (1887–1972), British-born American biochemist at Columbia University, known for the Eschweiler–Clarke reaction. Member Natl. Acad. Sci. USA. Jane Clarke (b. 1950). Biochemist at Cambridge known for work on folding and assembly of proteins. Steven Clarke (b. 1949). American biochemist at UCLA, known for work on molecular damage and molecular repair mechanisms. Roy Elwood Clausen (1891–1956).
=== Sun === Solar mass (M☉ = 2.0×1030 kg) is also often used in astronomy when talking about masses of stars or galaxies; for example, Alpha Centauri A has the mass of 1.1 suns, and the Milky Way has a mass of approximately 6×1011 M☉. Solar mass also has a special use when estimating orbital periods and distances of 2 bodies using Kepler's laws: a3 = MtotalT2, where a is length of semi-major axis in AU, T is orbital period in years and Mtotal is the combined mass of objects in M☉. In case of planet orbiting a star, Mtotal can be approximated to mean the mass of the central object. More specifically in the case of Sun and Earth the numbers reduce to Mtotal ~ 1, a ~ 1 and T ~ 1.
Sources: en.wikipedia.org
As a salt, its dominant use is as an emulsifier for the emulsion polymerization of fluoropolymers such as PTFE, polyvinylidene fluoride, and fluoroelastomers. For this use, 3M subsidiary Dyneon has a replacement emulsifer despite DuPont stating PFOA is an "essential processing aid". In the past PFOA was used in the production of Gore-Tex as it is PTFE-based. In PTFE processing, PFOA is in aqueous solution and forms micelles that contain tetrafluoroethylene and the growing polymer. PFOA can be used to stabilize fluoropolymer and fluoroelastomer suspensions before further industrial processing and in ion-pair reversed-phase liquid chromatography it can act as an extraction agent. PFOA also finds uses in electronic products and as an industrial fluorosurfactant. In a 2009 EPA study of 116 products, purchased between March 2007 and May 2008 and found to contain at least 0.01% fluorine by weight, the concentrations of PFOA were determined. Concentrations shown below range from not detected, or ND, (with the detection limit in parentheses) to 6750 with concentrations in nanograms of PFOA per gram of sample (parts per billion) unless stated otherwise.
=== Minimum wage === During his 2022 gubernatorial campaign, Moore said that he would accelerate the state's incremental increase to a minimum wage of $15 an hour by 2023. He also supports indexing the state's minimum wage to inflation. At the beginning of the 2023 legislative session, Moore introduced the Fair Wage Act, a bill that would accelerate the state's minimum wage build-up to reach $15 an hour by October 2023 and index the minimum wage to the consumer price index starting in July 2025, with increases capped at five percent per year. The Senate Finance Committee amended the bill to remove provisions linking it to the consumer price index and delayed the wage increase until January 1, 2024. Moore signed the bill into law on April 11, 2023. He also allocated $218 million in his first budget to support state service providers in keeping up with the accelerated wage increase.
===== UPMC Lemieux Sports Complex ===== The UPMC Lemieux Sports Complex, opened in 2015 in Cranberry Township, is a 185,000 square feet (17,200 m2) contains both a comprehensive outpatient facility for UPMC Sports Medicine and the primary training facilities for the NHL's Pittsburgh Penguins, and the secondary venue for their ECHL affiliate, the Wheeling Nailers. The outpatient clinic includes orthopedic, primary care, physical therapy, concussion, imaging, and sports performance services. The training facility includes two-full-sized ice rinks, training and locker rooms, video review facility, and executive offices.
However, since individual sensitivity to the development of this side effect is highly dose dependent and may vary depending which opioid analgesic is used, many patients can avoid this side effect simply through dose reduction of the opioid drug (usually accompanied by the addition of a supplemental non-opioid analgesic), rotating between different opioid drugs, or by switching to a milder opioid with a mixed mode of action that also counteracts neuropathic pain, particularly tramadol or tapentadol.
== Mechanism and toxicity == κ-Bungarotoxin works as a postsynaptic neurotoxin. The postsynaptic neurotoxin is a prolonged, potentially irreversible, competitive antagonist of neuronal nicotinic acetylcholine receptors (nAChRs). Though α-bungarotoxin specifically binds to muscle nAChRs, κ-bungarotoxin targets the α3 and α4 - though α4 to a lesser extent - subunits of the nAChR in the central and autonomic nervous system, specifically in the avian ciliary ganglia because the α3 subunit of the nAChR is the main ganglionic type. One of Kappa-Bungarotoxin's target sites is the same as that of Alpha-Bungarotoxin, whereas the second target site of the nicotinic receptor is exclusively bound by κ-bungarotoxin. This, because neuronal nAChRs contain a broader variety of subunits than muscle nAChRs. By binding with a high affinity to the acetylcholine binding site of the neuronal nAChRs, Kappa-Bungarotoxin blocks these receptors for an eventual acetylcholine to bind. Normally, activation of the neuronal nAChRs by acetylcholine would release several neurotransmitters and generate inward ion influx, creating action potentials. However, when Kappa-Bungarotoxin is bound to the neuronal nAChRs, it inhibits depolarization at 75 nM and thus synaptic transmission. This blockade leads to the disruption of neuronal communication in the central nervous system and ganglia, causing neuromuscular paralysis and respiratory failure in prolonged κ-bungarotoxin exposure.
Sources: en.wikipedia.org
=== DNA damage === Arsenic is reported to cause DNA modifications such as aneuploidy, micronuclei formation, chromosome abnormality, deletion mutations, sister chromatid exchange and crosslinking of DNA with proteins. It has been demonstrated that arsenic does not directly interact with DNA and it is considered a poor mutagen, but instead, it helps mutagenicity of other carcinogens. For instance, a synergistic increase in the mutagenic activity of arsenic with UV light has been observed in human and other mammalian cells after exposing the UV-treated cells to arsenic. A series of experimental observations suggest that the arsenic genotoxicity is primarily linked to the generation of reactive oxygen species (ROS) during its biotransformation. The ROS production is able to generate DNA adducts, DNA strand breaks, crosslinks and chromosomal aberrations. The oxidative damage is caused by modification of DNA nucleobases, in particular 8-oxoguanine (8-OHdG) which leads to G:C to T:A mutations. Inorganic arsenic can also cause DNA strand break even at low concentrations.
This kind of ore they often gather and lay on great heapes, where it heteth and rotteth, and will have a strong and loathsome smell; when being so rotten they cast on the land, as they do their muck, and thereof springeth good corn, especially barley ... After spring-tydes or great rigs of the sea, they fetch it in sacks on horse backes, and carie the same three, four, or five miles, and cast it on the lande, which doth very much better the ground for corn and grass. Today, algae are used by humans in many ways; for example, as fertilizers, soil conditioners, and livestock feed. Aquatic and microscopic species are cultured in clear tanks or ponds and are either harvested or used to treat effluents pumped through the ponds. Algaculture on a large scale is an important type of aquaculture in some places. Maerl is commonly used as a soil conditioner.
=== Emotional responses === Every emotional response has a behavioral, an autonomic, and a hormonal component. The hormonal component includes the release of adrenaline, an adrenomedullary response to stress controlled by the sympathetic nervous system. The major emotion studied in relation to adrenaline is fear. In an experiment, subjects who were injected with adrenaline expressed more negative and fewer positive facial expressions to fear films compared to a control group. These subjects also reported a more intense fear from the films and greater mean intensity of negative memories than control subjects. The findings from this study demonstrate that there are learned associations between negative feelings and levels of adrenaline. Overall, the greater amount of adrenaline is positively correlated with an aroused state of negative emotions. These findings can be an effect in part that adrenaline elicits physiological sympathetic responses, including an increased heart rate and knee shaking, which can be attributed to the feeling of fear regardless of the actual level of fear elicited from the video. Although studies have found a definite relation between adrenaline and fear, other emotions have not had such results. In the same study, subjects did not express a greater amusement to an amusement film nor greater anger to an anger film. Similar findings were also supported in a study that involved rodent subjects that either were able or unable to produce adrenaline.
=== Sexual effects === From the available evidence, it seems men who have been circumcised with the aid of a circumcision device experience unchanged or heightened sexual pleasure and satisfaction. There is some evidence such men also derive long time improvements in erectile function. The accumulated data show circumcision has no adverse physiological effect on sexual pleasure, function, desire, or fertility. There is some evidence that circumcision has no effect on pain with intercourse, premature ejaculation, intravaginal ejaculation latency time, erectile dysfunction, or difficulties with orgasm. There are popular misconceptions that circumcision benefits or adversely affects the sexual pleasure of the circumcised person. According to a 2014 review, the effect of circumcision on sexual partners' experiences is unclear as it has not been well studied. According to a policy statement by the Canadian Paediatric Society that was reaffirmed in 2021, "medical studies do not support circumcision as having an impact on sexual function or satisfaction for partners of circumcised individuals".
Sources: en.wikipedia.org
It consists of a three-amino-acid peptide, glycine-histidine-lysine, bound to one copper(II) ion. The peptide supplies four nitrogen donor atoms, and the resulting complex is stable in neutral aqueous solution. The metal-free peptide is usually called GHK.
The three letters are the standard one-letter codes for glycine, histidine, and lysine. The suffix -Cu indicates the coordinated copper ion. Cosmetic ingredient lists often use the alternative name copper tripeptide-1 for the same complex.
No. Free GHK is the peptide alone, while GHK-Cu contains a bound copper atom. The two differ in colour, charge, and binding behaviour, so any study that measures copper delivery must state which form was used.
Freezer temperatures are common for long-term retention. Light and moisture exposure should be limited. Working portions are best kept cold and used without repeated freeze-thaw cycles.