This is a working overview of copper(II) complex, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-09-29 and is reviewed periodically as new material appears.
Material described in research and cosmetic supply chains is typically a synthetic peptide supplied as a lyophilized powder. Purity is commonly reported through chromatographic separation, often at 95 percent or higher, while copper content is confirmed by separate elemental analysis. Batch variation in color and solubility can reflect residual counter-ions, moisture, or partial oxidation of the peptide. Because the complex is not a single regulatory entity, specifications differ between suppliers and are not standardized internationally.
GHK-Cu is a coordination complex formed between the tripeptide glycyl-L-histidyl-L-lysine and a copper(II) ion. The peptide binds copper through its histidine imidazole nitrogen, its terminal amino group, and a deprotonated amide nitrogen, creating a stable chelate ring. The resulting complex carries a distinctive blue to blue-violet color, which arises from copper d-d electronic transitions. In the solid state it is usually handled as a powder, while in solution the complex can dissociate and re-form depending on pH and competing ligands. The name copper tripeptide-1 is widely used in ingredient listings.
The tripeptide was first isolated from a human plasma filtrate in 1973 during studies of tissue repair factors. Later work detected the free peptide and its copper complex in saliva, urine, and wound fluid, suggesting a natural role in tissue remodeling. Plasma concentrations reported in early literature decline with age, a pattern often cited in discussions of skin aging. Whether these endogenous levels are directly functional or largely incidental remains an open question. The peptide sequence is conserved across mammalian species.
Endogenous GHK occurs in blood plasma, saliva, and urine, and reported plasma concentrations decline with age in several studies. Researchers have proposed that the peptide acts as a copper carrier that delivers the metal to cells and to sites of injury. That transport role is a hypothesis supported by binding measurements and tissue-distribution data rather than a settled mechanism, and the peptide is generally described as a minor contributor to total plasma copper transport. Values reported in wound fluid and certain tissue extracts are higher than in circulating plasma.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C14H24N6O4 | Free tripeptide, without copper |
| Molecular weight | About 340 g/mol | Peptide portion only |
| Appearance | Blue to violet powder | Color from copper coordination |
| Solubility | Soluble in water | pH influences dissolution |
| Common synonyms | Copper tripeptide-1, Cu-GHK | Seen on ingredient labels |
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.
Solid GHK-Cu is usually supplied as a lyophilized powder and is kept cold and dry. Moisture, light, and repeated temperature cycling shorten its useful life in the laboratory. In aqueous solution the complex undergoes slow hydrolysis of the peptide backbone and gradual loss of coordinated copper. Buffers containing strong chelators, such as EDTA, compete for the metal and strip it from the peptide. Working solutions are therefore prepared shortly before use, and leftover liquid is not returned to the stock container.
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.
Quality specifications for research material commonly state peptide purity, copper stoichiometry, counter-ion identity, and residual water content. Frequent counter-ions include acetate and trifluoroacetate, which differ in mass and in their effect on solubility and handling. Whether batch-to-batch differences in reported responses trace to these parameters or to assay conditions remains an open question, since published comparisons rarely control for all of them at once. Independent verification therefore normally pairs a purity measurement with an elemental copper measurement on the same lot.
Practical handling notes centre on limiting exposure to water, oxygen, and repeated temperature cycling. Weighed powder is often equilibrated to room temperature before opening to avoid condensation on the solid. Working solutions are typically divided into single-use aliquots and frozen rather than stored refrigerated for long periods. Reported shelf lives vary widely between laboratories, and no single set of conditions is universally treated as a reference standard, which complicates direct comparison of published stability figures.
Solutions of GHK-Cu respond strongly to pH, redox conditions, and the presence of competing chelators such as EDTA. Below roughly pH 4 the copper tends to dissociate, because the amide nitrogen donors become protonated and can no longer coordinate. Strongly alkaline conditions instead favour hydrolysis and precipitation of copper hydroxide. Dissolved oxygen and light accelerate breakdown of the peptide backbone, and the copper released during that process can catalyse further oxidation, so dry, cold, dark storage is the usual recommendation.
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.
An inhibition by tertiapin will result in a shorter cardiac action potential with loss of parasympathetic control, resulting in a faster heart rate ROMK is found in the kidneys where it contributes to K+ recycling. An inhibition will result in loss of potassium, as observed in Bartter syndrome, which can be caused by mutations in the ROMK channels.
A plebiscite on whether the Sanitary Board should have an official or unofficial majority was held in Hong Kong in June 1896. The result of the plebiscite was overwhelmingly for unofficial majority, however no constitutional changes were made for Sanitary Board, though the constitutions of the Executive and Legislative Council were changed as unofficial members were added as a result. The 1896 plebiscite is on record the only referendum conducted by the Hong Kong Government and could be seen as part of the first major debate on the constitutional reform in the crown colony during the 1890s. It was much earlier than the Governor Mark Aitchison Young's Young Plan in the 1940s and 1950s and the rise of the modern pro-democracy camp in the 1980s.
In an interview conducted in July 2010, when he was no longer a minister, Johnson admitted the decision to ban mephedrone was sped up after widespread reporting of deaths caused by the drug, and because the government wished to pass the law before parliament was dissolved prior to the upcoming general election. In January 2011, however, Johnson told the Scunthorpe Telegraph that the decision was based only on information from the ACMD. An editorial in the April 2010 edition of The Lancet questioned the decision to ban mephedrone, saying the ACMD did not have enough evidence to judge the potential harms caused by mephedrone and arguing that policy makers should have sought to understand why young people took it and how they could be influenced not to take it. Evan Harris, then the Liberal Democrat science spokesman, stated the ACMD "was not 'legally constituted'" as required by the Misuse of Drugs Act, when the report on cathinones was published, since after Taylor resigned, it lacked a veterinary surgeon. In the rush to make mephedrone illegal, the act that was passed specified the inactive enantiomer of mephedrone, leaving the active form legal until the loophole was closed in February 2011 by another act of parliament. In Chemistry World, John Mann, professor of chemistry at Queen's University Belfast, suggested the UK create a law similar to the Federal Analog Act of the United States, which would have made mephedrone illegal as an analog of cathinone.
=== Halides === Protactinium(V) fluoride is a white compound that forms tetragonal crystals, isomorphic to β-UF5. Protactinium(V) chloride forms yellow crystals where protactinium ions are arranged in pentagonal bipyramids and coordinated by 7 other ions. The coordination changes to octahedral in the brown protactinium(V) bromide, but is unknown for protactinium(V) iodide. The protactinium coordination in all its tetrahalides is 8, but the arrangement is square antiprismatic in protactinium(IV) fluoride and dodecahedral in the chloride and bromide. Brown-colored protactinium(III) iodide has been reported, where protactinium ions are 8-coordinated in a bicapped trigonal prismatic arrangement.
After oral administration, zopiclone is rapidly absorbed, with a bioavailability around 75–80%. Time to peak plasma concentration is 1–2 hours. A high-fat meal preceding zopiclone administration does not change absorption (as measured by AUC), but reduces peak plasma levels and delays its occurrence, thus may delay the onset of therapeutic effects. The plasma protein-binding of zopiclone has been reported to be weak, between 45 and 80% (mean 52–59%). It is rapidly and widely distributed to body tissues, including the brain, and is excreted in urine, saliva, and breast milk. Zopiclone is partly extensively metabolized in the liver to form an active N-demethylated derivative (N-desmethylzopiclone) and an inactive zopiclone-N-oxide. Hepatic enzymes playing the most significant role in zopiclone metabolism are CYP3A4 and CYP2E1. In addition, about 50% of the administered dose is decarboxylated and excreted via the lungs. In urine, the N-demethyl and N-oxide metabolites account for 30% of the initial dose. Between 7 and 10% of zopiclone is recovered from the urine, indicating extensive metabolism of the drug before excretion. The terminal elimination half-life of zopiclone ranges from 3.5 to 6.5 hours (5 hours on average). The pharmacokinetics of zopiclone in humans are stereoselective.
Sources: en.wikipedia.org
== Mechanism == As previously mentioned, BCKDC's primary function in mammals is to catalyze an irreversible step in the catabolism of branched-chain amino acids. However BCKDC has a relatively broad specificity, also oxidizing 4-methylthio-2-oxobutyrate and 2-oxobutyrate at comparable rates and with similar Km values as for its branched-chain amino acid substrates. The BCKDC will also oxidize pyruvate, but at such a slow rate this side reaction has very little physiological significance. The reaction mechanism is as follows. Please note that any of several branched-chain α-ketoacids could have been used as a starting material; for this example, α-ketoisovalerate was arbitrarily chosen as the BCKDC substrate.
Its frankly grandiose style is transporting in its way, as is the story itself, even in this watered-down form." She also complimented the African scenery, noting that "Cry Freedom can also be admired for Ronnie Taylor's picturesque cinematography". The Variety Staff felt Washington did "a remarkable job of transforming himself into the articulte [sic] and mesmerizing black nationalist leader, whose refusal to keep silent led to his death in police custody and a subsequent coverup." On Kline's performance, they noticed how his "low-key screen presence serves him well in his portrayal of the strong-willed but even-tempered journalist." Film critic Gene Siskel of the Chicago Tribune gave the film a thumbs up review calling it "fresh" and a "solid adventure" while commenting "its images do remain in the mind ... I admire this film very much." He thought both Washington's and Kline's portrayals were "effective" and "quite good". Similarly, Michael Price writing in the Fort Worth Press viewed Cry Freedom as often "harrowing and naturalistic but ultimately self-important in its indictment of police-state politics."
CoA + acetyl-[acyl-carrier-protein] Thus, the two substrates of this enzyme are acetyl-CoA and acyl carrier protein, whereas its two products are CoA and acetyl-acyl-carrier-protein. This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acetyl-CoA:[acyl-carrier-protein] S-acetyltransferase. Other names in common use include acetyl coenzyme A-acyl-carrier-protein transacylase, acetyl-CoA:ACP transacylase, [acyl-carrier-protein]acetyltransferase, [ACP]acetyltransferase, and ACAT. This enzyme participates in fatty acid biosynthesis.
=== Testing for insulin dysregulation === Due to the strong link between PPID and insulin resistance, testing is recommended for all horses suspected or confirmed to be suffering from PPID. There are two tests commonly used for insulin resistance: the oral sugar test and fasting insulin blood concentration. The fasting insulin concentration involves giving a horse a single flake of hay at 10 pm the night before testing, with blood being drawn the following morning. Both insulin and glucose blood levels are measured. Hyperinsulinemia suggests insulin resistance, but normal or low fasting insulin does not rule out PPID. This test is easy to perform, but is less sensitive than the oral sugar test. It is best used in cases where risks of laminitis make the oral sugar test potentially unsafe. The oral sugar test also requires giving the horse only a single flake of hay at 10pm the night before the test. The following morning, karo corn syrup is given orally, and glucose and insulin levels are measured at 60 and 90 minutes after administration. Normal or excessively high insulin levels are diagnostic. However, equivocal test results require retesting at a later date, or performing a different test. A similar test is available outside the US, in areas where corn-syrup products are less readily available, where horses are given a morning meal of chaff with dextrose powder, and blood insulin levels are measured 2 hours later.
Sources: en.wikipedia.org
N-Acetylcysteine ethyl ester (NACET, NAC-Et) is an antioxidant which acts as a lipophilic prodrug for N-acetylcysteine and subsequently glutathione, with improved bioavailability over N-acetylcysteine itself, and has been researched in animal studies as a potential treatment for diabetic retinopathy. It has also been sold as a "dietary supplement" in combination with glycine under the name GlyNAC-Et as a supposedly improved version of the older glycine-NAC combination GlyNAC which has been claimed to show efficacy in counteracting symptoms associated with aging as well as HIV infection, diabetes and nerve damage. Several related compounds such as γ-glutamylcysteine ethyl ester and glutathione ethyl ester have been investigated for similar applications.
== 2A function in FMDV virus == Foot-and-mouth disease virus (FMDV) is a virus in the genus Aphthovirus that causes foot-and-mouth disease in cattle. As a member of the family Picornaviridae, FMDV is a positive-sense, single-stranded RNA virus. 2A is located between the capsid proteins and polymerases and proteases required for the capsid assembly in the late stages of the infection. The incomplete ribosomal skipping during the viral RNA translation mediated by the 2A results in "ribosome drop off" in some cases, after which the translation doesn't restart. This leads to a prevalence of the N-terminal proteins and allows for the increased production of the structural proteins relative to the non-structural proteins.
Both The Guardian newspaper (UK) and the American non-profit publication ICIJ received documents in July 2014 revealing the details of past and present offshore clients of wealth managers Kleinwort Benson, including the Nando's restaurant group. The Guardian published its belief that, through the use of businesses in Malta, Guernsey and the Netherlands, Enthoven legally reduces the group's UK corporation tax bill by "up to a third." According to the British newspaper, Enthoven's profits eventually accumulate in the Kleinwort Benson-managed "Taro III Trust" that is based in Jersey and contains at least £750 million. While no member of the Enthoven family agreed to speak with The Guardian, a company representative explained that UK tax laws are not applicable to Enthoven, as "he is not resident in the US or the UK." The spokesperson also stated that, in the UK, Nando's paid corporation tax of £12.6 million on a profit of £58.2 million for the year ending February 2013. In its 2023 tax strategy, the company states that "Nando's policy is to maintain its tax affairs responsibly and transparently. Nando's doesn’t enter into transactions simply to secure tax advantages."
Sources: en.wikipedia.org
It is a complex of the tripeptide glycyl-L-histidyl-L-lysine with a copper(II) ion. The peptide coordinates the metal through its histidine, amino terminus, and an amide nitrogen. It is often listed simply as copper tripeptide-1.
The peptide and its copper form have been detected in human plasma, saliva, and urine. Early reports describe levels that fall with age. The functional meaning of these pools is still debated.
Chromatographic separation gives peptide purity, often reported as a percentage. Copper content is checked by a separate elemental method. Moisture and counter-ions may be reported as well.
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.