Everything below concerns Stability. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2025-09-25. Where a claim depends on a specific study, the study is described rather than over-claimed.
Research interest in GHK-Cu centers on its ability to deliver copper and to influence cellular processes in laboratory models. In cell culture and animal studies, the complex has been linked to collagen synthesis, antioxidant enzyme activity, and expression of genes associated with tissue remodeling. These effects are not equivalent to proven clinical outcomes. The mechanisms proposed include copper transfer to cuproenzymes, modulation of growth factor signaling, and interactions with extracellular matrix components. How much of the observed activity depends on intact GHK-Cu versus free copper or free peptide is not fully resolved.
The compound entered scientific literature in the 1970s, when plasma factors with copper-binding activity were isolated and characterized. Later work expanded into wound healing, skin biology, and cosmetic formulation, where copper tripeptide-1 became a recognized ingredient name. Most published studies remain preclinical or small-scale, and findings are often reported in specialized dermatology or peptide journals. Regulatory treatment varies: some jurisdictions allow it as a cosmetic ingredient, while research-grade material is sold for laboratory use. Questions about optimal delivery, target tissues, and long-term effects continue to be investigated rather than settled.
GHK-Cu is a coordination complex formed between the tripeptide glycyl-L-histidyl-L-lysine and a copper(II) ion. The peptide sequence is often abbreviated Gly-His-Lys, and the copper is bound through the histidine imidazole nitrogen and adjacent peptide nitrogens. The complex is frequently described as a 1:1 peptide-to-copper species. It occurs naturally in human plasma, saliva, and urine at low concentrations. Its endogenous levels have been reported to decline with age, although the precise physiological role of that change remains an open question.
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 |
|---|---|---|
| Chemical class | Copper-binding tripeptide complex | Includes Gly-His-Lys and Cu(II) |
| Molecular formula | C14H22CuN6O4 | Reported for the 1:1 complex |
| Appearance | Blue to blue-violet solid | Color arises from copper d-d transitions |
| Solubility class | Water-soluble; slightly soluble in polar organic solvents | Often prepared as aqueous stock |
| Typical storage | -20 °C, desiccated, protected from light | Limits oxidation and moisture uptake |
Routine handling calls for minimizing freeze-thaw cycles and preparing solutions shortly before use. Glass or inert plastic containers reduce adsorption and metal leaching. Working stocks are often kept at 2–8 °C for short periods, while long-term reference material stays at −20 °C or below. Light protection is prudent because prolonged exposure may accelerate oxidation of the peptide. Documentation of lot number, concentration, and preparation date supports reproducibility in laboratory work.
Analytical verification typically combines reversed-phase high-performance liquid chromatography with ultraviolet-visible detection. The copper complex absorbs visible light near 600–630 nm, giving a characteristic blue signal. Mass spectrometry confirms molecular mass and can detect free peptide or mismatched copper stoichiometry. Copper content is often measured independently by inductively coupled plasma mass spectrometry or atomic absorption spectroscopy. Purity, counterion identity, and residual solvents are additional quality-control parameters that methods may address.
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.
Dry material is normally held cold, commonly at -20 °C for long-term storage and 2 to 8 °C for working quantities, protected from light and moisture. Vials should be allowed to reach room temperature before opening so that condensation does not form on the powder. In liquid formulations the complex is generally kept near neutral to slightly acidic pH, because strongly alkaline conditions favour precipitation of copper hydroxide. Antioxidants or chelate-stabilising excipients are often added, though the specific approaches are proprietary and rarely published in detail.
The sequence now called GHK was first reported in the early 1970s after isolation from human plasma, where it was noted to influence liver cell behavior in laboratory preparations. Later work described a copper-binding form and its activity in fibroblast and wound-model experiments. Review articles frequently group the substance with other copper peptides. Concentrations in blood appear to fall with age in several small surveys, although the reason for this trend is not settled. Whether such a decline carries functional consequences remains an open question.
Published work on GHK-Cu concentrates largely on cell culture systems rather than whole organisms. Frequently used endpoints include collagen synthesis, expression of matrix metalloproteinases, and migration of fibroblasts. Some reports describe antioxidant behavior, while others stress delivery of copper into cells. These mechanisms are proposed rather than demonstrated, and the relative weight of each pathway is unclear. Human trials are few and generally small, so laboratory findings should not be read as confirmed clinical results.
GHK-Cu is a coordination complex formed between the tripeptide glycyl-L-histidyl-L-lysine and a copper(II) ion. The peptide backbone consists of glycine, histidine, and lysine joined in that order. Copper is held through the imidazole nitrogen of histidine and the alpha-amino group at the N-terminus, which together produce a square-planar arrangement around the metal center. The solid appears blue to violet, a color that originates from d-d electronic transitions within the copper coordination sphere. The complex is indexed under CAS number 89030-95-5.
=== Bioaccumulation and biomagnification === In marine species of the food web Bioaccumulation controls internal concentrations of pollutants, including PFAS, in individual organisms. When bioaccumulation is looked at in the perspective of the entire food web, it is called biomagnification, which is important to track because lower concentrations of pollutants in environmental matrices such as seawater or sediments, can very quickly grow to harmful concentrations in organisms at higher trophic levels, including humans. Notably, concentrations in biota can even be greater than 5000 times those present in water for PFOS and C10–C14 PFCAs. PFAS can enter an organism by ingestion of sediment, through the water, or directly via their diet. It accumulates mainly in areas with high protein content, in the blood and liver, but it is also found to a lesser extent in tissues.
=== 12 April === Russian-installed officials in Zaporizhzhia Oblast claimed that ten people were killed by Ukrainian shelling in Tokmak. One person was killed by Russian shelling in Kharkiv Oblast. Two people were killed in separate Russian attacks in Donetsk Oblast. Russia reported shooting down four drones over an oil refinery in Novoshakhtinsk. One drone fell in the grounds of the oil refinery. Another drone was reportedly shot down over Belgorod Oblast. A former SBU agent who defected to Russia shortly before the 2022 invasion was injured in a car bombing in Moscow. Russia and Ukraine conducted an exchange of war dead, with 99 Ukrainians being exchanged for 23 Russians. The HUR said that Russia had transferred 2,000 personnel from its Pacific Fleet and 400 personnel from the Russian Air Force's 11th Air and Air Defence Forces Army, in addition to halting the deployment of soldiers to Syria on rotation. It claimed that the transfers will either form new units or fill losses in existing units. Norway announced that it would transfer 22 F-16s to Ukraine as well as spare parts, simulators and other equipment to operate them.
== Other interests == Monaghan is an active member of the British Mass Spectrometry Society and has been given life membership for making a significant contribution to the practice of mass spectrometry in the UK. In 2003 the BMSS made John its first President with responsibility to promote the work done by the Society, particularly on the international stage and beyond the core MS community. Monaghan has also been a member and president of the Peterloo Speakers Club in Manchester. He is also a keen cricketer and football referee.
== Side effects == Side effects of doxylamine include dizziness, drowsiness, and dry mouth, among others. Doxylamine is a potent anticholinergic and has a side-effect profile common to such drugs, including blurred vision, dry mouth, constipation, muscle incoordination, urinary retention, mental confusion, and delirium. Because of its relatively long elimination half-life (10–12 hours), doxylamine is associated with next-day effects including sedation, drowsiness, grogginess, dry mouth, and tiredness when used as a hypnotic. This next-day sedation may be described as a "hangover effect". The shorter elimination half-life of diphenhydramine (4–8 hours) compared to doxylamine may give it an advantage over doxylamine as a sleep aid in this regard. Antihistamines like doxylamine are sedating initially but tolerance occurs with repeated use and can result in rebound insomnia upon discontinuation. Occasional case reports of coma and rhabdomyolysis have been reported with doxylamine overdose. This pattern is in contrast to diphenhydramine. Studies of doxylamine's carcinogenicity in mice and rats have produced positive results for both liver and thyroid cancer, especially in the mouse. The carcinogenicity of the drug in humans is not well-studied, and the International Agency for Research on Cancer lists the drug as "not classifiable as to its carcinogenicity to humans". Continuous and/or cumulative use of anticholinergic medications, including first-generation antihistamines, is associated with a higher risk of cognitive decline and dementia in older people.
2 March – Bertie O'Brien, 71, Gaelic footballer and hurler (St. Finbarr's, Cork senior teams). 3 March Camille Souter, 93, artist. Rita O'Hare, 80, Republican activist. 5 March – Maurice Scully, 70, poet. 10 March – Niall Brophy, 87, rugby union player (Leinster, national team, Lions). 12 March – Liam Kearns, 61, Gaelic footballer (Austin Stacks, Kerry senior team) and manager (Limerick, Laois, Tipperary, Offaly). 13 March – Tom Ryan, 81, hurler (Killenaule, Éire Óg, James Stephens, Tipperary senior team). 22 March – Marcus Wilson, 91, Gaelic footballer (St. Vincent's, Dublin senior teams). 25 March – Ger Glavin, 66, hurler (Midleton) and Gaelic footballer (Ballincollig, Imokilly, Cork senior team). 28 March – Jimmy Gray, 93, Gaelic footballer and hurler (Na Fianna, Dublin senior teams). 31 March – Harry Cassidy, 92, Gaelic footballer and manager (Bellaghy, Derry senior team). Born in Northern Ireland.
Sources: en.wikipedia.org
== Multi-chain polymerization == A monomer with functionality 3 has 3 functional groups that participate in the polymerization. This will introduce branching in a polymer and may ultimately form a cross-linked macrostructure. The point at which this three-dimensional 3D network is formed is known as the gel point, signaled by an abrupt change in viscosity. A more general functionality factor fav is defined for multi-chain polymerization, as the average number of functional groups present per monomer unit. For a system containing N0 molecules initially and equivalent numbers of two function groups A and B, the total number of functional groups is N0fav.
Apollo 11 was prepared with the goal of a July landing in the Sea of Tranquility, just half a year after the first crewed flight to the Moon. The crew, selected in January 1969, consisted of commander (CDR) Neil Armstrong, Command Module Pilot (CMP) Michael Collins, and Lunar Module Pilot (LMP) Edwin "Buzz" Aldrin. They trained for the mission until just before the launch day. On July 16, 1969, at 9:32 am EDT, the Saturn V rocket, AS-506, lifted off from Kennedy Space Center Launch Complex 39 in Florida. The trip to the Moon took just over three days. After achieving orbit, Armstrong and Aldrin transferred into the Lunar Module named Eagle, leaving Collins in the Command and Service Module Columbia, and began their descent. Despite the interruption of alarms from an overloaded computer caused by an antenna switch left in the wrong position, Armstrong took over manual flight control at about 180 meters (590 ft) to correct a slight downrange guidance error, and set the Eagle down on a safe landing spot at 20:18:04 UTC, July 20, 1969 (3:17:04 pm CDT). Six hours later, at 02:56 UTC, July 21 (9:56 pm CDT July 20), Armstrong left the Eagle to become the first human to set foot on the Moon.
=== Metals === Pure alkali metals are dangerously reactive with air and water and must be kept away from heat, fire, oxidising agents, acids, most organic compounds, halocarbons, plastics, and moisture. They also react with carbon dioxide and carbon tetrachloride, so that normal fire extinguishers are counterproductive when used on alkali metal fires. Some Class D dry powder extinguishers designed for metal fires are effective, depriving the fire of oxygen and cooling the alkali metal. Experiments are usually conducted using only small quantities of a few grams in a fume hood. Small quantities of lithium may be disposed of by reaction with cool water, but the heavier alkali metals should be dissolved in the less reactive isopropanol. The alkali metals must be stored under mineral oil or an inert atmosphere. The inert atmosphere used may be argon or nitrogen gas, except for lithium, which reacts with nitrogen. Rubidium and caesium must be kept away from air, even under oil, because even a small amount of air diffused into the oil may trigger formation of the dangerously explosive peroxide; for the same reason, potassium should not be stored under oil in an oxygen-containing atmosphere for longer than 6 months.
=== On the heart === Myostatin is expressed at very low levels in cardiac myocytes. Although its presence has been noted in cardiomyocytes of both fetal and adult mice, its physiological function remains uncertain. However, it has been suggested that fetal cardiac myostatin may play a role in early heart development. Myostatin is produced as promyostatin, a precursor protein kept inactive by the latent TGF-β binding protein 3 (LTBP3). Pathological cardiac stress promotes N-terminal cleavage by furin convertase to create a biologically active C-terminal fragment. The mature myostatin is then segregated from the latent complex via proteolytic cleavage by BMP-1 and tolloid metalloproteinases. Free myostatin is able to bind its receptor, ActRIIB, and increase SMAD2/3 phosphorylation. The latter produces a heteromeric complex with SMAD4, inducing myostatin translocation into the cardiomyocyte nucleus to modulate transcription factor activity. Manipulating the muscle creatinine kinase promoter can modulate myostatin expression, although it has only been observed in male mice thus far. Myostatin may inhibit cardiomyocyte proliferation and differentiation by manipulating cell cycle progression. This argument is supported by the fact that myostatin mRNA is poorly expressed in proliferating fetal cardiomyocytes. In vitro studies indicate that myostatin promotes SMAD2 phosphorylation to inhibit cardiomyocyte proliferation.
Sources: en.wikipedia.org
GHK-Cu is a complex of the tripeptide glycyl-L-histidyl-L-lysine with copper(II). The peptide binds copper through its histidine residue and neighboring amide nitrogens, forming a stable coordination compound. It is studied as a research chemical and used in some cosmetic formulations.
Yes, the peptide and its copper complex have been detected in human plasma, saliva, and urine. Endogenous concentrations are low, and reported levels change with age and physiological state. The biological significance of those changes is still an active area of study.
GHK refers to the free tripeptide without a bound copper ion. GHK-Cu contains copper(II) coordinated to the same peptide backbone. The presence of copper affects the complex's color, stability, and interaction with biological molecules.
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.