Coordination complex is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Updated 2026-06-23. Numbers and descriptions here follow the published literature rather than marketing material.
GHK-Cu is a coordination complex formed from the tripeptide glycyl-L-histidyl-L-lysine and a copper(II) ion. The peptide binds copper through its histidine imidazole nitrogen, the terminal amino group, and the deprotonated amide nitrogen. This arrangement creates a square-planar or distorted geometry around the metal center, depending on pH and the presence of competing ligands. The complex occurs naturally in human plasma, saliva, and urine at low concentrations, and its sequence is conserved across many vertebrate species.
Discovery of GHK is generally attributed to work in the 1970s that isolated a plasma factor influencing liver cell behavior. Subsequent studies identified the copper-binding tripeptide and its ability to chelate copper with high affinity. Early reports linked the complex to wound healing and tissue remodeling in animal models. The free peptide and the copper-bound form have different properties, so the two are distinguished in the literature. Whether endogenous GHK-Cu serves a single primary physiological role remains an open question.
The molecular weight and charge of GHK-Cu depend on the pH and the number of coordinated ligands. At neutral pH, the peptide typically binds one copper ion, but ternary complexes with other biomolecules can form. Spectroscopic methods such as electron paramagnetic resonance and circular dichroism are used to study the coordination environment. Reports on the exact geometry vary because the complex is dynamic in solution. Researchers often use synthetic GHK-Cu rather than extracted material to control stoichiometry and purity.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Peptide sequence | Gly-His-Lys | Tripeptide; copper binds via His and N-terminus |
| Copper stoichiometry | Typically 1 Cu(II) per peptide | Can form ternary complexes under some conditions |
| Molecular formula (peptide) | C14H24N6O4 | Free peptide; copper complex mass differs |
| Appearance (solid) | Blue to blue-green powder | Color derives from copper d-d transitions |
| Solubility | Soluble in water and polar solvents | Solubility depends on pH and counterions |
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.
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 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.
==== 2009 ==== In January 2009, Krasnaya Zvezda published an interview with Father Mikhail, the Orthodox priest, who said: "I attended military exercise "Kavkaz-2008" in South Ossetia, where our paratroopers worked out the skills of combat in the mountains. Unfortunately, those skills became useful too soon..." In late January 2009, Russian sergeant Aleksandr Glukhov ran away from Akhalgori District and requested a political asylum in Tbilisi. He had served in the 693rd regiment and he declared that he was deployed to South Ossetia in July 2008. In May 2009, Rossiyskaya Gazeta reported that hero of Russia, Denis Vetchinov, who died in South Ossetia, left the base of the Motor Rifle Division in Vladikavkaz for Tskhinvali on the early morning of 7 August 2008. In June 2009, Russian General Vyacheslav Borisov told Echo of Moscow in an interview: "I headed the South Ossetian and the Georgian directions. You know, we even regularly hold exercises in those areas. And our troops had full practice by holding exercises one week before right there in the same place. And we had only concluded and went." In July 2009, Russian journalist Ella Polyakova wrote that some Russian soldiers had told her that they arrived in South Ossetia on 4 August 2008, while their records claimed that they were stationed in North Ossetia. In July 2009, Russian blogger published an interview with soldier Maksim Belyaev, who said: "Our combined battalion of peacekeepers was stationed in North Ossetia. We should have replaced in August another battalion of the peacekeeping mission, located in Tskhinvali.
Traumatic acid is a monounsaturated dicarboxylic acid that occurs naturally in plants. The compound was first isolated from wounded bean plants by American chemists James English Jr. and James Frederick Bonner and Dutch scientist Arie Jan Haagen-Smit in 1939. Traumatic acid is a potent wound healing agent in plants ("wound hormone") that stimulates cell division near a trauma site to form a protective callus and to heal the damaged tissue. It may also act as a growth hormone, especially in inferior plants (e.g. algae). Traumatic acid is biosynthesized in plants by non-enzymatic oxidation of traumatin (12-oxo-trans-10-dodecenoic acid), another wound hormone. Traumatic acid, was among the first biologically active molecules isolated from plant tissues. This dicarboxylic acid was shown to be a potent wound healing agent in plant that stimulates cell division near a wound site, it derives from 18:2 or 18:3 fatty acid hydroperoxides after conversion into oxo- fatty acids. At normal conditions, traumatic acid is a solid, crystalline, water-insoluble substance. The salts and esters of traumatic acid are called traumatates. Traumatic acid is used as an intermediate in prostaglandin synthesis. It is also a constituent of some pharmaceutical products, such as the odontostomatologic gel Restomyl, due to its mucosal re-epithelialization activity.
== Benefits == SASP can aid in signaling to immune cells for senescent cell clearance, with specific SASP factors secreted by senescent cells attracting and activating different components of both the innate and adaptive immune system. The SASP cytokine CCL2 (MCP1) recruits macrophages to remove cancer cells. Although transient expression of SASP can recruit immune system cells to eliminate cancer cells as well as senescent cells, chronic SASP promotes cancer. Senescent hematopoietic stem cells produce a SASP that induces an M1 polarization of macrophages which kills the senescent cells in a p53-dependent process. Autophagy is upregulated to promote survival. SASP factors can maintain senescent cells in their senescent state of growth arrest, thereby preventing cancerous transformation. Additionally, SASP secreted by cells that have become senescent because of stresses can induce senescence in adjoining cells subject to the same stresses, thereby reducing cancer risk. SASP can play a beneficial role by promoting wound healing. SASP may play a role in tissue regeneration by signaling for senescent cell clearance by immune cells, allowing progenitor cells to repopulate tissue. In development, SASP also may be used to signal for senescent cell clearance to aid tissue remodeling. The ability of SASP to clear senescent cells and regenerate damaged tissue declines with age. In contrast to the persistent character of SASP in the chronic inflammation of multiple age-related diseases, beneficial SASP in wound healing is transitory.
== Description == The Wound Man illustrates various injuries that a person might receive through war, accident, or disease: cuts and bruises from multiple weapons, rashes and pustules, thorn scratches, and the bites of venomous animals. The figure also includes some schematic anatomical outlines of several organs within his unusual, transparent abdomen.
Sources: en.wikipedia.org
=== Pregnancy === HLA-G plays a role in immune tolerance in pregnancy, being expressed in the placenta by extravillous trophoblast cells (EVT), while the classical MHC class I genes (HLA-A and HLA-B) are not. As HLA-G was first identified in placenta samples, many studies have evaluated its role in pregnancy disorders, such as preeclampsia and recurrent pregnancy loss. Its downregulation is related to HLA-A and -B downregulation results in protection from cytotoxic T cell responses, but would in theory result in a missing self response by natural killer cells. HLA-G is a ligand for natural killer (NK) cell inhibitory receptor KIR2DL4, and therefore expression of this HLA by the trophoblast defends it against NK cell-mediated death. The presence of soluble HLA-G (sHLA-G) in embryos is associated with better pregnancy rates. In order to optimize pregnancy rates, there is significant evidence that a morphological scoring system is the best strategy for the selection of embryos. However, presence of soluble HLA-G might be considered as a second parameter if a choice has to be made between embryos of morphologically equal quality.
== Further reading == Müller, Bodo (2006). Coatings formulation: an international textbook. Urlich Poth. Hannover: Vincentz. ISBN 3-87870-177-2. OCLC 76886114. Spyrou, Emmanouil (2012). Powder coatings chemistry and technology (3 ed.). Vincentz Network. ISBN 978-3-86630-884-8. OCLC 828194496. Titanium and titanium alloys, edited by C. Leyens and M. Peters, Wiley-VCH, ISBN 3-527-30534-3, table 6.2: overview of several coating systems and fabrication processes for titanium alloys and titanium aluminides (amended) Coating Materials for Electronic Applications: Polymers, Processes, Reliability, Testing by James J. Licari; William Andrew Publishing, Elsevier, ISBN 0-8155-1492-1 High-Performance Organic Coatings, ed. AS Khanna, Elsevier BV, 2015, ISBN 978-1-84569-265-0
Experiments on its genotoxicity at high doses are inconsistent. Its oxidized form TBBQ may be responsible for some toxic effects. There exists a wide margin of safety between food-additive doses and doses used in studies. There have been reports of vision disturbances in individuals exposed to this chemical.
Sources: en.wikipedia.org
The Independent Office for Police Conduct launches an investigation into the incident the following day. The UK government publishes an updated list of 214 schools and colleges in England affected by reinforced autoclaved aerated concrete. 20 October – 2023 Mid Bedfordshire by-election: Labour MP Alistair Strathern wins the constituency of Mid Bedfordshire, with the Conservatives' share of the vote falling by 28.7%, one of the largest swings of the post-war era. 2023 Tamworth by-election: Labour MP Sarah Edwards wins the constituency of Tamworth, with the Conservatives' share of the vote falling by 25.6%. Leeds Bradford Airport is closed, causing delays to flights, after a TUI plane skids on the runway during landing as a result of heavy rainfall caused by Storm Babet. The airport reopens again the following day. Scotland Yard has reported an increase in the number of antisemitic crimes in London since the start of the Israel–Hamas conflict, with 218 incidents reported between 1 and 18 October; the number of incidents reported over the same period in 2022 was 15. 21 October – The UK government announces reforms to recycling in England that will see the majority of households receive a weekly collection of food waste by 2026, and a designated list of items councils must recycle. Police and Transport for London officials are investigating after video emerged online of a tube driver on the Central Line chanting pro-Palestinian slogans on a train. The driver is subsequently suspended pending an investigation by TfL.
=== Digestion into peptide fragments === Peptides longer than about 50–70 amino acids long cannot be sequenced reliably by the Edman degradation. Because of this, long protein chains need to be broken up into small fragments that can then be sequenced individually. Digestion is done either by endopeptidases such as trypsin or pepsin or by chemical reagents such as cyanogen bromide. Different enzymes give different cleavage patterns, and the overlap between fragments can be used to construct an overall sequence.
LSU rRNA subtypes have been called ribozymes because ribosomal proteins cannot bind to the catalytic site of the ribosome in this area (specifically the peptidyl transferase center, or PTC). The SSU rRNA subtypes decode mRNA in its decoding center (DC). Ribosomal proteins cannot enter the DC. The structure of rRNA is able to drastically change to affect tRNA binding to the ribosome during translation of other mRNAs. In 16S rRNA, this is thought to occur when certain nucleotides in the rRNA appear to alternate base pairing between one nucleotide or another, forming a "switch" that alters the rRNA's conformation. This process is able to affect the structure of the LSU and SSU, suggesting that this conformational switch in the rRNA structure affects the entire ribosome in its ability to match a codon with its anticodon in tRNA selection as well as decode mRNA.
Sources: en.wikipedia.org
GHK-Cu is a complex of the tripeptide glycyl-L-histidyl-L-lysine with copper(II). The peptide coordinates the metal through its histidine imidazole, terminal amino group, and amide nitrogen. It is studied in biochemistry and dermatological research.
Yes, the peptide and its copper complex have been detected in human plasma, saliva, and urine. Endogenous concentrations are low and vary with physiological state. Its natural functions are not fully established.
Copper binding changes the peptide's charge, shape, and reactivity. The complex can participate in redox chemistry and interact with proteins differently than the free peptide. These differences are why studies specify whether they used GHK or GHK-Cu.
It is a complex of a three-amino-acid peptide, glycine, histidine and lysine, bound to a single copper(II) ion. The metal is held mainly by the histidine side chain and the peptide backbone. Most commercial material is supplied as an acetate salt rather than as the free complex.