glycyl-histidyl-lysine raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2026-01-18. Anything still debated is marked as such rather than presented as settled.
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.
GHK-Cu is a coordination complex formed between the tripeptide glycyl-L-histidyl-L-lysine and copper(II). The peptide sequence consists of glycine, histidine, and lysine, and its imidazole and amino groups provide binding sites for the metal ion. In the complex, copper is held through nitrogen donors from the histidine side chain, the N-terminal amine, and deprotonated amide nitrogens. The resulting compound is intensely blue and water-soluble. It occurs naturally in human plasma, saliva, and urine at low concentrations.
Copper binds to the peptide through the histidine imidazole nitrogen and the terminal amino group, forming a stable square-planar complex. Binding constants reported for copper(II) with GHK are high, so the peptide competes effectively for copper in solution. The complex absorbs visible light, which gives solutions a blue to violet colour. Whether the metal-free peptide has a distinct biological function of its own is still an open question; some work treats it mainly as a copper delivery vehicle, while other work reports peptide-specific effects.
The compound was first isolated from human plasma in the 1970s by Loren Pickart, who later described copper-binding activity in liver and other tissues. Early reports focused on its presence in blood and its ability to carry copper between proteins. Commercial and cosmetic use of the term 'copper peptide' has since broadened, and labels rarely distinguish GHK-Cu from other copper-binding fragments. This naming overlap makes literature searching harder, because cosmetic ingredient lists, supplier catalogues and laboratory papers use different vocabularies for the same molecule.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Copper(II) tripeptide complex | Contains glycyl-histidyl-lysine ligand |
| Peptide sequence | Gly-His-Lys | N-terminal glycine, C-terminal lysine |
| Molecular formula | C14H22CuN6O4 | Commonly cited for the 1:1 complex |
| Appearance | Blue to blue-violet solid | Color arises from copper d-d transitions |
| Solubility | Water-soluble | Also dissolves in some polar solvents |
Solutions of GHK-Cu respond strongly to pH, redox conditions, and the presence of competing chelators such as EDTA. Below roughly pH 4 the copper tends to dissociate, because the amide nitrogen donors become protonated and can no longer coordinate. Strongly alkaline conditions instead favour hydrolysis and precipitation of copper hydroxide. Dissolved oxygen and light accelerate breakdown of the peptide backbone, and the copper released during that process can catalyse further oxidation, so dry, cold, dark storage is the usual recommendation.
Routine characterisation relies on reversed-phase high-performance liquid chromatography for peptide purity, paired with mass spectrometry for identity confirmation. Ultraviolet-visible spectroscopy detects the metal centre through its absorption band in the visible region, and inductively coupled plasma mass spectrometry quantifies total copper so that a metal-to-peptide ratio can be calculated. Amino acid analysis confirms the expected residue composition. Together these techniques establish concentration, identity, and stoichiometry, but none of them directly reports biological activity.
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.
Identity and purity are assessed mainly by reversed-phase high-performance liquid chromatography with ultraviolet detection, often paired with mass spectrometry to confirm the expected mass. Copper content is measured separately by inductively coupled plasma optical emission spectrometry or atomic absorption spectroscopy, because the peptide assay alone does not establish the metal-to-peptide ratio. Visible spectroscopy provides a rapid check on complex integrity through the absorption band in the visible region. Agreement between the peptide assay and the copper assay is the practical test of whether a sample is the intended complex rather than a mixture.
Proposed mechanisms for copper peptide activity center on delivery of copper ions to cells and on peptide fragments acting as signaling molecules. Copper is a cofactor for enzymes involved in collagen cross-linking and antioxidant defense, and the peptide may improve its availability at target sites. Separately, the tripeptide and its breakdown products have been reported to influence gene expression in cultured fibroblasts. Much of this evidence comes from laboratory cell cultures and animal models rather than controlled human trials. The relative contribution of the copper ion and the peptide sequence is therefore not fully settled.
Stability depends on temperature, light exposure, moisture, and the presence of oxidizing or reducing agents. Solid material held dry and protected from light is generally more stable than aqueous solutions, which can undergo gradual degradation. Recommended storage in much of the literature is a freezer at around minus twenty degrees Celsius for long-term retention, with working aliquots kept cold and shielded from light. Repeated freeze-thaw cycles and alkaline pH are commonly noted as factors that accelerate loss of the intact complex, though exact degradation rates vary.
Solid GHK-Cu appears as a blue to blue-violet powder, and the colour is a direct consequence of copper coordination. The complex dissolves readily in water and in many polar solvents, while the free peptide behaves differently. Solubility in nonpolar media is low, which limits its use in oil-based systems. Solutions are typically prepared fresh because the dissolved form is more exposed to hydrolysis and to loss of the metal ion than the dry powder. Working concentrations are usually low, and preparation notes often specify the solvent and the order of addition.
Dry material is typically held at low temperature, often around minus twenty degrees Celsius, and protected from moisture and light. Copper complexes can release their metal ion under acidic conditions or in the presence of competing chelators. Hydrolysis of the peptide backbone is a slower but real pathway, and the histidine residue is susceptible to oxidation over long periods. Stability statements therefore depend on formulation, pH, and container, and they should be read as conditional rather than absolute.
BioLegend is a global developer and manufacturer of antibodies and reagents used in biomedical research located in San Diego, California. It was incorporated in June 2002 and has since expanded to include BioLegend Japan KK, where it is partnered with Tomy Digital Biology Co., Ltd. in Tokyo, BioLegend Europe in the United Kingdom, BioLegend GmbH in Germany, and BioLegend UK Ltd in the United Kingdom. In July 2021, BioLegend was acquired by PerkinElmer for $5.25 billion and now operates as Revvity. BioLegend manufactures products in the areas of neuroscience, cell immunophenotyping, cytokines and chemokines, adhesion, cancer research, T regulatory cells, stem cells, innate immunity, cell-cycle analysis, apoptosis, and modification-specific antibodies. Reagents are created for use in flow cytometry, proteogenomics, ELISA, immunoprecipitation, Western blotting, immunofluorescence microscopy, immunohistochemistry, and in vitro or in vivo functional assays.
A. Hari Reddi (born October 20, 1942) is a University of California Distinguished Professor and inaugural holder of the Lawrence J. Ellison Endowed Chair in Musculoskeletal Molecular Biology at the University of California, Davis. His research played an indispensable role in the identification, isolation and purification of bone morphogenetic proteins (BMPs) that are involved in bone formation and repair. The molecular mechanism of bone induction studied by Professor Reddi led to the conceptual advance in tissue engineering that morphogens in the form of metabologens bound to an insoluble extracellular matrix scaffolding act in collaboration to stimulate stem cells to form cartilage and bone. The Reddi laboratory has also made important discoveries unraveling the role of the extracellular matrix in bone and cartilage tissue regeneration and repair. Professor Reddi was previously the Virginia M. and William A. Percy Chair and Professor in Orthopaedic Surgery, Professor of Biological Chemistry, and Professor of Oncology at the Johns Hopkins University School of Medicine. He was also a past faculty member at the University of Chicago and senior scientist at the National Institutes of Health.
The nobelium can then be isolated by exploiting its tendency to form the divalent state, unlike the other trivalent actinides: under typically used elution conditions (bis-(2-ethylhexyl) phosphoric acid (HDEHP) as stationary organic phase and 0.05 M hydrochloric acid as mobile aqueous phase, or using 3 M hydrochloric acid as an eluant from cation-exchange resin columns), nobelium will pass through the column and elute while the other trivalent actinides remain on the column. However, if a direct "catcher" gold foil is used, the process is complicated by the need to separate out the gold using anion-exchange chromatography before isolating the nobelium by elution from chromatographic extraction columns using HDEHP.
=== Medical === Desomorphine was previously used in Germany, Austria, and Switzerland for the treatment of severe pain. While medical usage of desomorphine was terminated in 1981, during the final years leading up to that it was being used to treat a single patient in Bern, Switzerland with a rare illness. While desomorphine was found to be faster acting and more effective than morphine for the rapid relief of severe pain, its shorter duration of action and the relatively more severe respiratory depression produced at equianalgesic doses, as well as a high incidence of other side effects such as hypotension and urinary retention, were felt to outweigh any potential advantages.
Sources: en.wikipedia.org
Column C is the original assignment by Corey and Pauling. Column K is that of Koltun's patent. Column J is the color scheme used by the molecular visualizer Jmol. Column R is the scheme used by Rasmol; when two colors are shown, the second one is valid for versions 2.7.3 and later. Column P consists of the colors in the PubChem database managed by the United States National Institute of Health. All colors are approximate and may depend on the display hardware and viewing conditions.
=== Time === Moscow serves as the reference point for the time zone used in most of European Russia, Belarus, and Crimea. These areas operate in Moscow Standard Time (MSK, МСК), which is 3 hours ahead of UTC (or UTC+3). Daylight saving time is no longer observed in Moscow. According to geographical longitude, the average solar noon in Moscow occurs at 12:30.
=== Energy use === Early assessments of energy use in grey matter signaling suggested that 95% was attributed to neurons and 5% to astrocytes. However, after discovering that action potentials were more efficient than initially believed, the energy budget was adjusted: 70% for dendrites, 15% for axons, and 7% for astrocytes. Previous accounts assumed that astrocytes captured synaptic K+ solely via Kir4.1 channels. However, it's now understood they also utilize Na+/K+ ATPase. Factoring in this active buffering, astrocytic energy demand increases by >200%. This is supported by 3D neuropil reconstructions indicating similar mitochondrial densities in both cell types, as well as cell-specific transcriptomic and proteomic data, and tricarboxylic acid cycle rates. Therefore "Gram-per-gram, astrocytes turn out to be as expensive as neurons".
Sources: en.wikipedia.org
In Greece, during a civil war involving the communist-led partisan movement ELAS-EAM, British Special Forces terminated arms supplies to the ELA-ELAM, pro-monarchist armed forces were strengthened. On the political front, Americans, with British encouragement, attempted to dismantle ELAS-EAM socialist structures in the countryside, and an anti-communist swing gradually occurred. Western Allies conducted meetings in Italy in March 1945 with German representatives to forestall a takeover by Italian communist resistance forces in northern Italy and to hinder the potential there for post-war influence of the civilian Italian Communist Party. The affair caused a major rift between Stalin and Churchill, and in a letter to Roosevelt on 3 April Stalin complained that the secret negotiations did not serve to "preserve and promote trust between our countries".
=== Sleep === MCH and the hormone orexin have an antagonistic relationship with one another with regards to the sleep cycle, with orexin being almost entirely active during wake periods and MCH being more active during sleep periods. MCH also promotes sleep, and within a sleep period increased levels of MCH seem to increase the amount of time spent in REM sleep and slow waves sleep. Increased levels of MCH can also increase the amount of time spent in both REM and NREM, which in turn increases total sleep duration. Increased levels of sugar promotes MCH and its effect on sleep and conserving energy.
Current issues for the CV reside in outbreaks of violence with criminal organizations for control of drug routes and turf wars with militias over territories, such as the Complexo do Alemão (which is sometimes considered the "headquarters" of the organization).
Sources: en.wikipedia.org
GHK is the free tripeptide, while GHK-Cu includes a bound copper(II) ion. The copper complex is the form most often studied for skin and wound-related activity. The two names are sometimes used interchangeably in product labeling, but they refer to distinct chemical species.
Yes, it is found in human plasma, saliva, and urine. Its concentration in plasma tends to decrease with age. This natural presence is one reason researchers have investigated its role in tissue maintenance.
No, GHK-Cu is not an approved drug in major markets. It is widely used as a cosmetic ingredient, where it is listed under names such as copper tripeptide-1. Any therapeutic claims would require separate regulatory review.
The letters GHK are the one-letter codes for glycine, histidine and lysine, the three amino acids in the peptide. The suffix Cu indicates that the peptide is bound to a copper ion, normally copper(II).