A practical reference on glycyl-histidyl-lysine: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2025-09-24 and is reviewed periodically as new material appears.
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.
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 the copper(II) complex of the tripeptide glycyl-L-histidyl-L-lysine, a short sequence of three amino acids. The peptide was first isolated from human plasma in 1973 during research on factors that influence tissue repair in liver. Its ability to bind copper ions became a central point of interest because the metal changes the peptide's chemistry and its behaviour in laboratory systems. Today the compound appears in cosmetic formulations, cell-culture studies, and biochemistry literature under several names.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Copper(II) peptide complex | Peptide chain coordinated to a single metal ion |
| CAS number | 89030-95-5 | Indexed for the peptide-copper complex |
| Molecular formula | C14H22CuN6O4 | Approximate formula for a one-to-one complex |
| Appearance | Blue to violet solid | Color from copper d-d transitions |
| Solubility class | Freely soluble in water | Also dispersible in some polar solvents |
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.
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.
The peptide portion consists of three amino acids: glycine, histidine and lysine. Copper(II) coordinates through the imidazole nitrogen of histidine, the alpha-amino group of glycine and a deprotonated amide nitrogen of the backbone, producing a roughly square-planar geometry. This arrangement gives the complex its characteristic blue-to-violet colour and helps it resist dissociation in water. Reported stability constants are high, although values differ between studies because of differences in ionic strength and measurement method.
=== Osmoregulation === In teleost fish, prolactin is the principal freshwater-adapting hormone, preventing ion loss by stimulating ionocyte differentiation in gill epithelia. This is an ancient function of prolactin, conserved across vertebrate evolution. In mammals, the osmoregulatory role is less prominent but includes effects on amniotic fluid regulation and renal sodium handling.
While Marco Polo wrote of Mongolian Tatar troops in the time of Kublai Khan who carried sun-dried skimmed milk as "a kind of paste", the first modern production process for dried milk was invented by the Russian doctor Osip Krichevsky in 1802. The first commercial production of dried milk was organized by the Russian chemist M. Dirchoff in 1832. In 1855, T. S. Grimwade took a patent on a dried milk procedure, though William Newton had patented a vacuum drying process as early as 1837. In modern times, powdered milk is usually made by spray drying nonfat skimmed milk, whole milk, buttermilk or whey. Pasteurized milk is first concentrated in an evaporator to approximately 50 percent milk solids. The resulting concentrated milk is then sprayed into a heated chamber where the water almost instantly evaporates, leaving fine particles of powdered milk solids. Alternatively, the milk can be dried by drum drying. Milk is applied as a thin film to the surface of a heated drum, and the dried milk solids are then scraped off. However, powdered milk made this way tends to have a cooked flavour, due to caramelization caused by greater heat exposure. Another process is freeze drying, which preserves many nutrients in milk, compared to drum drying. The drying method and the heat treatment of the milk as it is processed alters the properties of the milk powder, such as its solubility in cold water, its flavour, and its bulk density.
== Treatment == As of 2018, there is no cure for GSD, and treatment is restricted to manage symptoms and associated problems. Thus, sodium bicarbonate is recommended to treat metabolic acidosis, and antioxidants, among them vitamins E and C, can reduce oxidative damage.
Sources: en.wikipedia.org
As with SSRIs, the abrupt discontinuation of an SNRI usually leads to withdrawal, or "discontinuation syndrome", which could include states of anxiety and other symptoms. Therefore, it is recommended that users seeking to discontinue an SNRI slowly taper the dose under the supervision of a professional. Discontinuation syndrome has been reported to be markedly worse for venlafaxine when compared to other SNRIs. As such, as tramadol is related to venlafaxine, the same conditions apply. This is likely due to venlafaxine's relatively short half-life and therefore rapid clearance upon discontinuation. In some cases, switching from venlafaxine to fluoxetine, a long-acting SSRI, and then tapering off fluoxetine, may be recommended to reduce discontinuation symptoms. Signs and symptoms of withdrawal from abrupt cessation of an SNRI include dizziness, anxiety, insomnia, nausea, sweating, and flu-like symptoms, such as lethargy and malaise.
In 1992, Holton patented an improved process with an 80% yield, and BMS took the process in-house and started to manufacture paclitaxel in Ireland from 10-deacetylbaccatin isolated from the needles of the European yew. In early 1993, BMS announced that it would cease reliance on Pacific yew bark by the end of 1995, effectively terminating ecological controversy over its use. This announcement also made good their commitment to develop an alternative supply route, made to the NCI in their cooperative research and development agreement (CRADA) application of 1989. As of 2013, BMS was using the semisynthetic method utilizing needles from the European yew to produce paclitaxel. Another company which worked with BMS until 2012, Phyton Biotech, Inc., uses plant cell fermentation (PCF) technology. By cultivating a specific Taxus cell line in fermentation tanks, they no longer need ongoing sourcing of material from actual yew tree plantations. Paclitaxel is then captured directly from the suspension broth by a resin allowing concentration to highly enriched powder containing about 40% paclitaxel. The compound is then purified by one chromatographic step followed by crystallization. Compared to the semisynthesis method, PCF eliminates the need for many hazardous chemicals and saves a considerable amount of energy. In 1993, paclitaxel was discovered as a natural product in Taxomyces andreanae, a newly described endophytic fungus living in the yew tree.
==== Universities, libraries, and academic research ==== Conversely, academia and libraries are concerned that narrow copyright and TDM exceptions restrict access to research for AI training. Major academic publishers restrict universities from using subscribed databases for AI training without permission, while simultaneously selling access to commercial AI developers. This creates a "triple payment" problem where publicly funded research is paid for multiple times by universities. Advocacy groups argue publishers use contract law to override statutory rights, hindering the UK's sovereign AI research capacity. In response, Jisc advised universities to resist restrictive AI clauses in publisher licences. The UK's TDM exception is limited to non-commercial research, which groups like Knowledge Rights 21 argue will hobble the UK's "AI for Science" strategy.
Sources: en.wikipedia.org
It is the copper complex of the tripeptide glycyl-L-histidyl-lysine. The metal ion is held by the histidine imidazole group and the peptide N-terminus. Most research on it concerns skin and wound models.
The tripeptide was first isolated from human plasma and has also been reported in saliva and urine. Plasma levels appear to decline with age in some small studies. Those observations rest on limited sample sizes.
It is not authorized as a systemic medicine in most countries. Cosmetic preparations list it as an ingredient rather than an active pharmaceutical substance. Legal status therefore differs by jurisdiction.
The peptide is glycyl-L-histidyl-L-lysine, a three-amino-acid sequence commonly abbreviated GHK. It binds a single copper(II) ion under typical laboratory conditions. The free peptide and the copper complex are separate chemical species with different properties.