Everything below concerns copper(II) complex. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-04-01. Numbers and descriptions here follow the published literature rather than marketing material.
GHK-Cu is a coordination complex formed between the tripeptide glycyl-L-histidyl-lysine and a copper(II) ion. The peptide sequence is conventionally written as Gly-His-Lys, abbreviated GHK. Copper binds through the imidazole nitrogen of histidine, the alpha-amino group, and a deprotonated amide nitrogen, producing a square-planar geometry. The complex carries a net positive charge near physiological pH and is intensely blue in aqueous solution. The metal-free peptide is often written simply as GHK, while the copper-bound form is written GHK-Cu.
The compound was first isolated from human plasma by the biochemist Loren Pickart in 1973. Early work identified it as a factor that altered the behavior of cultured liver cells, and later studies linked it to connective tissue and wound-related processes. Reported plasma concentrations fall markedly between roughly age twenty and age sixty, a pattern that generated interest in copper peptide biology. Whether that decline has functional consequences remains an open question, because differences observed across age groups do not by themselves establish causation. Research interest later expanded into cosmetic and tissue-culture settings.
Mechanistic accounts focus on how the complex delivers copper and how the released peptide interacts with the extracellular matrix. Copper is an essential cofactor for lysyl oxidase and other enzymes involved in collagen and elastin cross-linking, and GHK is one of several peptides able to carry the metal. Reported effects include altered gene expression in fibroblasts and changes in matrix metalloproteinase activity, although many of these findings come from cell culture rather than whole organisms. The relative contribution of the peptide backbone, the copper ion, and downstream copper metabolism is not fully resolved.
Stability of the complex in solution depends on pH, temperature, and the presence of competing ligands. It is generally described as more resistant to breakdown than the metal-free chain, since coordination reduces susceptibility to enzymatic attack. Oxidation and hydrolysis can nevertheless proceed over time in aqueous media. Storage guidance in laboratory settings commonly involves refrigeration, protection from light, and avoidance of strongly alkaline conditions. Published data on long-term behaviour vary considerably and depend on the specific matrix.
Handling practices for the solid material emphasise low temperature and dryness. The lyophilised or powdered form is typically kept at refrigerator or freezer temperatures together with a desiccant. Working solutions are often prepared fresh, because repeated freeze-thaw cycles and extended storage may alter the complex. Glass or inert plastic containers are preferred over materials that could leach metal ions into the preparation. Such practices follow general peptide conventions rather than substance-specific regulations.
Analytical verification commonly relies on high-performance liquid chromatography for purity assessment and mass spectrometry for identity confirmation. Spectroscopic methods such as UV-visible absorption and electron paramagnetic resonance can probe the metal centre itself, since the d9 configuration of copper(II) produces characteristic signals. Elemental analysis or plasma-based techniques quantify copper content. Because each method reports a different aspect of the same sample, purity figures are most meaningful when the technique and its detection wavelength are stated alongside the value.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C14H22CuN6O4 as the complex | Free peptide is C14H24N6O4 |
| Molecular weight | About 402 g/mol | Free peptide is about 340 g/mol |
| Appearance | Blue solid or blue solution | Color from copper d-d transitions |
| Solubility class | Water-soluble; poor in nonpolar solvents | Ionic character favors aqueous media |
| Common synonyms | Copper tripeptide-1; glycyl-L-histidyl-L-lysine copper | INCI listing uses copper tripeptide-1 |
Laboratory studies describe GHK-Cu as a source of copper that cells can take up, with reported effects on collagen, elastin, and glycosaminoglycan synthesis in cultured fibroblasts. The peptide also appears in wound-repair research, where it is linked to the activity of matrix metalloproteinases and their inhibitors. These observations come largely from cell and animal models. How directly the complex controls any single pathway in intact human skin remains an open question, and reported effects depend on concentration, vehicle, and exposure time.
Copper takes part in redox chemistry, and the same property that makes it useful in enzymes can generate reactive oxygen species when the ion is loosely bound. GHK chelates copper through imidazole, amino, and amide nitrogen donors, which reduces the amount of free copper in solution. Whether that chelation is protective, neutral, or harmful in a given tissue is not settled. Laboratory assays report both antioxidant and pro-oxidant behavior, depending on the conditions and the readout used.
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.
=== In mutations === All known leptin mutations except one are associated with low to undetectable immunoreactive leptin blood levels. The exception is a mutant leptin reported in January 2015 that is not functional, but is detected with standard immunoreactive methods. It was found in a massively obese 2+1⁄2-year-old boy who had high levels of circulating leptin that had no effect on leptin receptors, so he was functionally leptin-deficient.
=== Multi-Stream Transport (MST) === Multi-Stream Transport is a feature first introduced in the DisplayPort 1.2 standard. It allows multiple independent displays to be driven from a single DP port on the source devices by multiplexing several video streams into a single stream and sending it to a branch device, which demultiplexes the signal into the original streams. Branch devices are commonly found in the form of an MST hub, which plugs into a single DP input port and provides multiple outputs, but it can also be implemented on a display internally to provide a DP output port for daisy-chaining, effectively embedding a 2-port MST hub inside the display. Theoretically, up to 63 displays can be supported, but the combined data rate requirements of all the displays cannot exceed the limits of a single DP port (17.28 Gbit/s for a DP 1.2 port, or 25.92 Gbit/s for a DP 1.3/1.4 port). In addition, the maximum number of links between the source and any device (i.e. the maximum length of a daisy-chain) is 7, and the maximum number of physical output ports on each branch device (such as a hub) is 7. With the release of MST, standard single-display operation has been retroactively named "SST" mode (Single-Stream Transport). Daisy-chaining is a feature that must be specifically supported by each intermediary display; not all DisplayPort 1.2 devices support it. Daisy-chaining requires a dedicated DisplayPort output port on the display. Standard DisplayPort input ports found on most displays cannot be used as a daisy-chain output.
== Side effects == Sedation and somnolence are the principal side effects (occasionally, they are also the intended effects) of phenobarbital. Central nervous system effects such as dizziness, nystagmus, and ataxia are also common. In elderly patients, it may cause excitement and confusion, while in children, it may result in paradoxical hyperactivity. Phenobarbital is a cytochrome P450 hepatic enzyme inducer. It binds transcription factor receptors that activate cytochrome P450 transcription, thereby increasing its amount and thus its activity. Caution is to be used with children. Among anticonvulsant drugs, behavioural disturbances occur most frequently with clonazepam and phenobarbital.
Sources: en.wikipedia.org
== Tables == The following tables give the elements with primordial nuclides (half-life of most stable isotope > 108 years). A list of nuclides sorted by half-life is found instead at List of nuclides. The tables of elements are sorted by decreasing number of nuclides per element. Stable and unstable nuclides are given, with symbols for the unstable ones in italics. All the primordial isotopes of each element are given in order of decreasing abundance on Earth, regardless of stability. By convention, nuclides are counted as "stable" if they have never been observed to decay by experiment or from observation of decay products (so that nuclides unstable in theory, such as tantalum-180m, are counted as stable). The first table is for even-atomic numbered elements, which tend to have far more primordial nuclides, due to the stability conferred by proton pairing. A second separate table is given for odd-atomic numbered elements, which tend to have far fewer stable and long-lived nuclides.
Zopiclone, sold under the brand name Imovane among others, is a benzodiazepine-like drug (Z-drug) used as a pharmaceutical treatment for insomnia. While molecularly distinct from benzodiazepine drugs, zopiclone's mechanism of action is similar: it increases the transmission of the neurotransmitter gamma-aminobutyric acid (GABA) in the central nervous system, via positive allosteric modulation at GABAA neurons. Zopiclone is considered a sedative and CNS depressant. Zopiclone and other benzodiazepine-like drugs like zaleplon and zolpidem are addictive. Within days to weeks, the body can become accustomed to the effects of zopiclone. The risk of developing tolerance with benzodiazepine-like drugs is comparable to benzodiazepines. When the dose is then reduced or the drug is abruptly stopped, withdrawal symptoms similar to those of benzodiazepine withdrawal may result. Benzodiazepine-like drugs decrease sleep latency by 10 to 20 minutes. However, no benzodiazepine-like drug has shown clinically significant increase in total sleep time. Zopiclone is recommended only to be taken at the lowest effective dose, with a duration of 2–3 weeks, for short-term insomnia. Use of zopiclone more than 4 weeks is not recommended. It is dangerous to take with benzodiazepines, sedatives, alcohol or other drugs affecting the central nervous system. In the United States, zopiclone is not commercially available, although its active stereoisomer, eszopiclone, is.
He worked as a music journalist and ran a magazine publishing business, launching Flexipop magazine in 1980 with ex-Record Mirror journalist Barry Cain. Robin Lustig (born 30 August 1948, London); was foreign correspondent in Madrid for Reuters; worked for The Observer as editor and Middle East correspondent; also presented The World Tonight, Newsstand, Stop Press, and File on 4 for Radio 4, and Newshour on the BBC World Service; presented programme covering sudden death of Diana, Princess of Wales, hours after announcement was made; also presented Talking Point (later renamed Have Your Say) for BBC World Service, BBC World TV; guests included Nelson Mandela, Thabo Mbeki, Olusegun Obasanjo, Hugo Chávez and Tony Blair; later worked on The World Tonight and Newshour; for BBC World Service, has presented every UK election night programme since 1997 as well as United States presidential election programmes; reported on elections in Iran, Israel, Japan, Russia and Zimbabwe; presented The World Tonight from Afghanistan, China, Iran, Iraq, Japan, Kosovo and Mexico; was awarded Gold Medal at the New York Radio Festival and broadcast live from Moscow on last day of Soviet Union; in 1998, won Sony Silver Award; was described in The Times as "arguably the best news presenter anywhere in radio after John Humphrys"; received Charles Wheeler award for outstanding contribution to broadcast journalism.
Sources: en.wikipedia.org
=== Other === The use of honey has been recommended as a temporary intervention for known or suspected button cell battery ingestions to reduce the risk and severity of injury to the esophagus caused by the battery prior to its removal. There is no evidence that honey is beneficial for treating cancer, although honey may be useful for controlling side effects of radiation therapy or chemotherapy used to treat cancer. Consumption is sometimes advocated as a treatment for seasonal allergies due to pollen, but scientific evidence to support the claim is inconclusive. Honey is generally considered ineffective for the treatment of allergic conjunctivitis. Honey has a mild laxative effect which has been noted as being helpful in alleviating constipation and bloating.
Confluentic acid is an organic compound belonging to the chemical class known as depsides. It serves as a secondary metabolite in certain lichens and plays a role in distinguishing closely related species within the genus Porpidia. In 1899, Friedrich Wilhelm Zopf isolated a compound from Lecidea confluens, which he initially named confluentin and noted for its melting point of 147–148 °C. This substance demonstrated the ability to turn litmus paper red and, when interacting with alkali, decomposed into carbon dioxide and phenol-like compounds. Zopf subsequently revised the chemical formula and melting point of the compound. Siegfried Huneck renamed it confluentinic acid in 1962, characterising it as optically inactive, with distinct colour reactions and solubility properties, and determined its molecular formula as C28H36O8. Confluentic acid can be identified using thin-layer chromatography and high-performance liquid chromatography. An alternative visual detection method involves examining the lichen's thallus or apothecium (fruiting body) under a microscope on a slide treated with potassium hydroxide, which reveals oil droplets indicative of confluentic acid. Several structural analogues of confluentic acid have been isolated from a variety of lichen species.
Terahertz metamaterials interact at terahertz frequencies, usually defined as 0.1 to 10 THz. Terahertz radiation lies at the far end of the infrared band, just after the end of the microwave band. This corresponds to millimeter and submillimeter wavelengths between the 3 mm (EHF band) and 0.03 mm (long-wavelength edge of far-infrared light).
== Description == This clade circumscribes five subordinate clades: two traditional tribes (Hypocalypteae and Indigofereae) and three informal clades (the mirbelioids, the millettioids, and Hologalegina), as well as several minor taxa. The name of this clade is informal and is not assumed to have any particular taxonomic rank like the names authorized by the ICBN or the ICPN. The clade does not currently have a node-based definition.
Sources: en.wikipedia.org
It is the copper(II) complex of the tripeptide glycyl-L-histidyl-lysine, a sequence of three amino acids. The copper ion is held by the histidine imidazole, the terminal amino group, and an amide nitrogen. The bound form is distinct from the free peptide in charge, color, and stability.
Copper(II) complexes absorb light in the red part of the visible spectrum, so transmitted light appears blue. The absorption arises from electronic transitions within the copper d-orbitals, which are split by the surrounding ligands. The intensity and exact wavelength shift somewhat with pH, solvent, and ligand arrangement.
The free peptide and the copper-bound complex are studied as separate species and do not always behave the same way in assays. Some reported responses are attributed to copper delivery, while others are attributed to the peptide sequence itself. Which fraction drives a given observation is often unresolved in the published work.
Reverse-phase high-performance liquid chromatography with ultraviolet detection is the most common approach. Purity is expressed as a share of total peak area at a specified wavelength. Mass spectrometry is then used to confirm molecular identity.