The short version of copper(II) centre fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-04-27 and is reviewed periodically as new material appears.
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.
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) peptide complex | Coordination compound rather than a simple salt |
| Peptide sequence | Glycyl-L-histidyl-L-lysine | Abbreviated GHK in most literature |
| Molecular formula | C14H22N6O4Cu | Reported for the 1:1 complex |
| Principal binding site | Histidine imidazole nitrogen | Backbone amides contribute additional coordination |
| Common synonym | Copper tripeptide-1 | Used in ingredient and product labelling |
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.
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.
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.
== N == N-formylmethionine - N-formylmethionine leucyl-phenylalanine - N-methyl-D-aspartate receptor - N-methylaspartate - N-terminus - NADH - NADPH - NaKATPase - native state - nef gene product - neoplasm protein - Nernst equation - nerve - nerve growth factor - nerve growth factor receptor - nerve tissue protein - nerve tissue protein S 100 - nervous system - neurobiology - neurofilament protein - neurokinin A - neurokinin K - neurokinin-1 receptor - neurokinin-2 receptor - neuron - neuronal cell adhesion molecule - neuropeptide - neuropeptide receptor - neuropeptide Y - neuropeptide Y receptor - neuroscience - neurotensin - neurotensin receptor - neurotransmitter - neurotransmitter receptor - neutral theory of molecular evolution - neutron - neutron activation analysis - NF-kappa B - nicotinic receptor - nitrogen - nitroglycerine - Nobel Prize in Chemistry - non-competitive inhibition - nuclear lamina - nuclear localization signal - nuclear magnetic resonance - NMR - nuclear protein - nucleic acid - nucleic acid regulatory sequence - nucleic acid repetitive sequence - nucleic acid sequence homology - nucleon - nucleophile - nucleoside - nucleosome - nucleotide - nutrition
Sedation Constipation Flushing Perspiration Heat intolerance Dizziness or fainting Weakness Fatigue Drowsiness Constricted pupils Dry mouth Nausea and vomiting Low blood pressure Headache Heart problems such as chest pain or fast heartbeat Abnormal heart rhythms Respiratory problems such as trouble breathing, slow or shallow breathing (hypoventilation), lightheadedness, or fainting Weight gain Memory loss Itching Difficulty urinating Swelling of the hands, arms, feet, and legs Mood changes, (e.g., euphoria, disorientation) Blurred vision Decreased libido, difficulty in reaching orgasm, or impotence Missed menstrual periods Skin rash Central sleep apnea When used for opioid maintenance therapy, Methadone is generally administered as an oral liquid. Methadone has been implicated in contributing to significant tooth decay. Methadone causes dry mouth, reducing the protective role of saliva in preventing decay. Other putative mechanisms of methadone-related tooth decay include craving for carbohydrates related to opioids, poor dental care, and a general decrease in personal hygiene. These factors, combined with sedation, have been linked to the causation of extensive dental damage.
=== Chemistry === Protein hydrolysis is a useful route to the isolation of individual amino acids. Examples include cystine from hydrolysis of hair, tryptophan from casein, histidine from red blood cells, and arginine from gelatin.
== Theories and models == The brain disease model of addiction posits that an individual's exposure to an addictive drug is the most significant environmental risk factor for addiction. In a review in The New England Journal of Medicine, Marc Lewis argued that the brain disease model gives a misleading and incomplete account, and that the brain changes it describes are better understood as a form of learning. Lewis was among a group of researchers who launched the Addiction Theory Network in 2018 to challenge the model and argue that addiction is better explained by choice, learning and social context.
Sources: en.wikipedia.org
=== Fold switching === Some proteins have multiple native structures, and change their fold based on some external factors. For example, the KaiB protein switches fold throughout the day, acting as a clock for cyanobacteria. It has been estimated that around 0.5–4% of PDB (Protein Data Bank) proteins switch folds.
In the early 2000s, 7-Eleven and Dentsu introduced a corporate mascot named Open-Chan (Open 小將), an extraterrestrial dog who wears a rainbow-shaped crown from a fictional planet known as Planet Open to be a "cartoon spokesperson" for the store chain in Taiwan. Open-Chan quickly grew in popularity among Taiwanese children soon after its initial debut. After Open-Chan's subsequent rise to prominence in Taiwan, the character was even introduced in Japan. The unique convenience store culture formed by President Chain Store (7-Eleven in Taiwan) has become a part of Taiwanese culture. 7-Eleven Taiwan also operates an MVNO called ibon mobile, which offers prepaid and postpaid SIM cards using the FarEasTone network.
Under Lenin, the government gave small language groups their own writing systems. The development of these writing systems was highly successful, even though some flaws were detected. During the later days of the USSR, countries with the same multilingual situation implemented similar policies. A serious problem when creating these writing systems was that the languages differed dialectally greatly from each other. When a language had been given a writing system and appeared in a notable publication, it would attain 'official language' status. There were many minority languages which never received their own writing system; therefore, their speakers were forced to have a second language. There are examples where the government retreated from this policy, most notably under Stalin where education was discontinued in languages that were not widespread. In 1938, Stalin mandated all schools to teach Soviet schoolchildren the Russian language. It did not stop children from getting an education in their native language (the language they grew up speaking), but they would also be required to learn how to speak the Russian language. Stalin saw this as necessary from a military perspective, because it would be easier for everyone to communicate. Despite only being mandated in 1938, children of different ethnicities were already being enrolled in schools teaching Russian beforehand because knowing the Russian language would open up a lot of opportunities for a person.
Sources: en.wikipedia.org
=== Industrial applications === Laccases have found a wide range of application, from food additive and beverage processing to biomedical diagnosis, and as cross‐linking agents for furniture construction or in the production of biofuels. The tyrosinase‐induced polymerization of peptides offers facile access to artificial mussel foot protein analogues. Next generation universal glues can be envisioned that perform effectively even under rigorous seawater conditions and adapt to a broad range of difficult surfaces.
=== MBT/CBT index === The methylation of branched tetraethers (MBT) and cyclization of branched tetraethers (CBT) indices relate abundances and distributions of bacterially-produced brGDGTs to relative changes in soil pH and mean annual air temperature. Further research is needed to assess seasonal bias, appropriate calibration protocols, and whether the brGDGT distributions record air or soil temperature.
Autotrophs that produced organic compounds from CO2, either photosynthetically or by inorganic chemical reactions; Heterotrophs that obtained organics from leakage of other organisms Saprotrophs that absorbed nutrients from decaying organisms Phagotrophs that were sufficiently complex to envelop and digest particulate nutrients, including other organisms. The eukaryotic cell seems to have evolved from a symbiotic community of prokaryotic cells. DNA-bearing organelles like mitochondria and chloroplasts are remnants of ancient symbiotic oxygen-breathing bacteria and cyanobacteria, respectively, where at least part of the rest of the cell may have been derived from an ancestral archaean prokaryote cell. The archean prokaryote cell concept is often termed as the endosymbiotic theory. There is still debate about whether organelles like the hydrogenosome predated the origin of mitochondria, or vice versa: see the hydrogen hypothesis for the origin of eukaryotic cells. How the current lineages of microbes evolved from this postulated community is currently unsolved, but subject of extensive research by biologists, stimulated by new discoveries in genome science.
Sources: en.wikipedia.org
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.
The chain occurs in human plasma, saliva, and urine. Measured amounts are reported to fall with age. Copper binding by the sequence is treated as part of normal metal handling in tissue.
The bound copper(II) centre contributes to redox behaviour and to stability under physiological conditions. Free copper ions can participate in reactions that generate reactive species, while chelated metal is generally more controlled. The chain may also serve as a carrier for copper in experimental systems.
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).