A practical reference on copper complex: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2026-08-01 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 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.
Published studies describe the complex in several research contexts, including collagen synthesis, antioxidant behaviour, and wound repair models. Much of this work is conducted in cultured cells or in small animal systems, and the findings are frequently cited in reviews of copper peptides. Direct clinical evidence in humans is comparatively limited, and reported outcomes vary with formulation and study design. Whether free chain or metal-bound form was used is not always stated, a point that complicates comparison between reports.
GHK-Cu is a coordination complex formed between the peptide glycyl-L-histidyl-L-lysine and a copper(II) ion. The unbound chain, abbreviated GHK, consists of three amino acids and occurs naturally in human plasma, saliva, and urine. Binding of the metal is mediated mainly by the imidazole nitrogen of the histidine residue together with backbone amides, producing a stable chelate. Ingredient nomenclature often lists the same substance as copper tripeptide-1. Its charge and solubility behaviour differ from those of the metal-free chain.
The copper-binding activity of this sequence was described in the 1970s during studies of liver tissue and plasma factors. Early work identified the peptide as a component that influenced copper uptake by cells and that appeared in wound fluid. Later investigations examined its presence across species, reporting the same chain in human and animal samples. A decline in measured concentration with age became a recurring observation, although the underlying causes remain incompletely characterised.
| 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 |
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.
The International Nomenclature of Cosmetic Ingredients lists the substance as copper tripeptide-1, the name that appears on most topical product labels. Related designations include copper peptide and GHK-Cu, and the hyphenated form is common in research literature. In cosmetics the material is regulated as an ingredient rather than as a drug, so products may reach the market without evidence of the effects claimed for them. Whether those effects are clinically meaningful is an open question, since most supportive data come from laboratory work and small trials.
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.
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 importation of mephedrone into the UK was banned on 29 March 2010. The next day, the ACMD in the UK published a report on the cathinones, including mephedrone, and recommended they be classified as Class B drugs. On 7 April 2010, the Misuse of Drugs Act 1971 (Amendment) Order 2010 was passed by parliament, making mephedrone and other substituted cathinones, Class B drugs from 16 April 2010. Prior to the ban taking effect, mephedrone was not covered by the Misuse of Drugs Act 1971. It was, though, an offence under the Medicines Act to sell it for human consumption, so it was often sold as "plant food" or "bath salts", although it has no use as these products; this, too, was possibly illegal under the Trade Descriptions Act 1968. In the US, similar descriptions have been used to describe mephedrone, as well as methylenedioxypyrovalerone (MDPV). In May 2010, the Republic of Ireland made mephedrone illegal, followed by Belgium, Italy, Lithuania, France and Norway in June and Russia in July. In August 2010, Austria and Poland made it illegal and China announced it would be illegal as of 1 September 2010. Mephedrone had been reported to be used in Singapore in February 2010, but it was made illegal in November 2010. In December 2010, following the advice of the EMCDDA, mephedrone was made illegal throughout the EU, a move Switzerland also made shortly afterwards. Countries which have not already banned it, such as the Netherlands, Greece and Portugal, will need to change legislation to comply with the EU ruling.
=== Nuclear fission === The longest-lived and most abundant isotope, 231Pa, can fission from fast neutrons exceeding ~1 MeV. 233Pa, the other isotope of protactinium produced in nuclear reactors, also has a fission threshold of 1 MeV.
=== Function === PNECs may play a role with chemoreceptors in hypoxia detection. This is best supported by the presence of an oxygen-sensitive potassium channel coupled to an oxygen sensory protein in the rabbit lumenal membrane. They are hypothetically involved in regulating localized epithelial cell growth and regeneration through a paracrine mechanism, whereby their signaling peptides are released into the environment. In addition, they contain neuroactive substances which are released from basal cytoplasm. These substances induce autonomic nerve terminals or vasculature in the deep lamina propria.
=== Modern era === In the 16th century Aquileia fell under the Habsburg County of Gorizia (later the Princely County of Gorizia and Gradisca), a part of the Holy Roman Empire. The patriarchal diocese was finally officially suppressed in 1751, and the sees of Udine and Gorizia were established from its territory. During the Napoleonic Wars Aquileia was annexed to the Napoleonic Kingdom of Italy by the 1807 Treaty of Fontainebleau. It returned to Austrian control in 1815 following the Congress of Vienna, initially as part of the Kingdom of Illyria, then the reconstituted Gorizia and Gradisca (part of the Austrian Littoral). Following the Austro-Hungarian defeat in World War I, Aquileia passed to the Kingdom of Italy in 1920 (Treaty of Rapallo).
=== Simple versus differential === Simple Staining is a technique that only uses one type of stain on a slide at a time. Because only one stain is being used, the specimens (for positive stains) or background (for negative stains) will be one color. Therefore, simple stains are typically used for viewing only one organism per slide. Differential staining uses multiple stains per slide. Based on the stains being used, organisms with different properties will appear different colors allowing for categorization of multiple specimens. Differential staining can also be used to color different organelles within one organism which can be seen in endospore staining.
Sources: en.wikipedia.org
The expected structure of the neurotoxin consists of four disulfide bonds, which are arranged in the following manner: 1–4, 2–5, 3–8, 6–7. Three of the disulfide bonds are believed to form an inhibitor cystine knot, which is known to increase resistance to heat denaturation and proteolysis. Transcriptomics has revealed the presence of both an N-terminal signal peptide and a pro peptide, which are cleaved after translation.
Cohen (1952), former co-owner of the Boston Celtics and the Brooklyn Nets; former chairman and CEO of the Madison Square Garden Corporation Lawrence K. Grossman (1952), president of PBS 1976–1984 and NBC News 1985–1988 Richard Wald (1952), former president of NBC News 1973–1977 Robert A. Belfer (1955), oilman and philanthropist, namesake of the Belfer Center for Science and International Affairs at Harvard University Thomas Ludlow Chrystie II (1955), first chief financial officer of Merrill Lynch & Company and creator of the Cash Management Account Alfred Lerner (1955), chairman of MBNA Bank and ex-owner of the Cleveland Browns Richard Ravitch (1955), chairman of the Metropolitan Transportation Authority and the Bowery Savings Bank Sid Sheinberg (1955), head of Universal Pictures Barry F. Sullivan (1955), chairman and CEO of First Chicago Bank, deputy mayor of New York City under David Dinkins Edward Botwinick (1956), IT entrepreneur and inventor, co-founder of Timeplex Franklin A. Thomas (1956), former president of The Ford Foundation James R. Barker (1957), chairman of Interlake Steamship Company, former chairman and CEO of Moore-McCormack Peter L.
Joshua Coon is a professor of chemistry and biomolecular chemistry and the inaugural holder of the Thomas and Margaret Pyle Chair at the University of Wisconsin–Madison, and an affiliate of the Morgridge Institute for Research. Coon develops scientific instruments to measure molecules in living systems. He focuses specifically on the use of mass spectrometry to measure the molecular mass of biomolecules, and its application to proteomics. Joshua Coon, along with John Syka, developed electron-transfer dissociation (ETD) while working as a postdoctoral student in Donald Hunt's lab at the University of Virginia.
Fei hua qing han (simplified Chinese: 飞花轻寒; traditional Chinese: 飛花輕寒; pinyin: Fēi huā qīng hán) is an apocryphal poem falsely attributed to Li Bai, an influential 8th-century Chinese poet. The poem attracted attention in the Chinese Internet community when some people deciphered a hidden message in it that says "Go to hell Japan, Koizumi must die" (日本去死, 小泉定亡). It was later revealed that the poem was written around 2003 to 2004. "Fei hua qing han" roughly means "a cold and flying chain of flowers".
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.
GHK denotes the unbound chain of three amino acids. GHK-Cu describes the form in which a copper(II) ion is held by that chain. The two are not interchangeable in solution, since charge, molecular weight, and reactivity differ.