glycyl-histidyl-lysine comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Last reviewed on 2026-01-17. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Endogenous GHK occurs in blood plasma, saliva, and urine, and reported plasma concentrations decline with age in several studies. Researchers have proposed that the peptide acts as a copper carrier that delivers the metal to cells and to sites of injury. That transport role is a hypothesis supported by binding measurements and tissue-distribution data rather than a settled mechanism, and the peptide is generally described as a minor contributor to total plasma copper transport. Values reported in wound fluid and certain tissue extracts are higher than in circulating plasma.
The sequence carries three residues in the order glycine, histidine, lysine, which places a small, flexible chain around a single metal centre. Compared with larger copper-binding proteins, the complex is compact and its coordination chemistry can be reproduced with synthetic peptide in a laboratory. Published structural work agrees on the nitrogen donor set but differs in the exact geometry assigned under some conditions, so the arrangement is best treated as well characterised in outline rather than fixed in every detail.
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 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.
| 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 |
Stability of GHK-Cu is influenced by light, oxygen, moisture, pH, and temperature. Solid material is generally kept desiccated and frozen to reduce hydrolysis and oxidation, while aqueous solutions are best prepared fresh or stored cold in aliquots. Repeated freeze-thaw cycles can promote aggregation, precipitation, or peptide degradation. Copper coordination may change under strongly acidic or alkaline conditions, potentially altering the complex's spectroscopic properties. Published long-term stability data for specific matrices, such as cosmetic emulsions or biological buffers, are limited, so shelf-life claims should be treated as formulation-specific rather than universal.
Quality control for GHK-Cu relies on documentation and independent testing rather than a single accepted standard. A certificate of analysis may report peptide purity, copper content, residual solvents, water content, and microbial limits, but the underlying methods and acceptance criteria vary by supplier. Verification can include mass confirmation, amino acid analysis, and comparison with a reference standard when one is available. Open questions include how different copper-binding modes or peptide isomers affect measured activity and whether conventional purity assays capture those differences. Buyers of research-grade material typically need to request raw data rather than rely solely on a summary certificate.
Laboratory characterization of GHK-Cu typically combines separation, spectroscopic, and elemental techniques. Reverse-phase high-performance liquid chromatography is widely used to assess peptide purity, often with ultraviolet detection near the copper-related absorption band or with mass spectrometry for identity confirmation. Because the molecule contains copper, elemental methods such as inductively coupled plasma mass spectrometry or atomic absorption spectroscopy are used to quantify metal content and confirm stoichiometry. No single universal pharmacopeial monograph exists for GHK-Cu. Laboratories therefore validate their own methods, and reported purity values depend on the chosen assay and calibration standards.
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.
GHK-Cu is the copper-binding complex formed by the tripeptide glycyl-L-histidyl-L-lysine and a copper(II) ion. The free peptide is usually written as GHK, and the complex is written as GHK-Cu or Cu-GHK. The sequence was identified in human plasma and later detected in saliva and urine. Its name comes from the single-letter codes of glycine, histidine and lysine. The complex is widely described as a naturally occurring carrier of copper in blood rather than as a free peptide with its own hormonal role.
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.
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.
Having succumbed to dementia prior to the elevation of Hanover, it is unlikely that he ever understood that he had gained an additional kingship, and he took no role in its governance. Functional administration of Hanover was usually handled by a viceroy, which during the later years of George III's reign and the reigns of Kings George IV and William IV from 1816 to 1837, was Adolph Frederick, George III's youngest surviving son. When Queen Victoria succeeded to the British throne in 1837, the 123-year personal union of Great Britain and Hanover ended. Unlike in Britain, semi-Salic law operated in Hanover, prohibiting the accession to the throne by a female if any male of the dynasty had survived. Ernest Augustus, now the eldest surviving son of George III, succeeded to the throne as King of Hanover. Adolph Frederick, the younger brother and long-time Viceroy, returned to Britain. Ernest Augustus had a personally strained relationship with his niece Queen Victoria, and they frequently squabbled over family affairs. Domestically, his reign began with a constitutional crisis as he tried to suspend parliament and nullify the written constitution of 1819. He also presided over the country during the turbulent Revolutions of 1848. His son, George V, assumed the throne in 1851.
=== Tigecycline === Tigecycline, a member of the glycylcyclines antibiotics, has proven to be an effective therapy against Enterobacteriaceae that typically display tetracycline resistance, because tigecycline has a higher binding affinity with ribosomal sites than tetracycline has. Tigecycline is capable of killing almost all of the ESBLs and multidrug-resistant (MDR) E. coli isolates and the large majority of ESBL and MDR isolates of Klebsiella species. A 2008 review of 42 studies of in vitro susceptibility of bacteria to tigecycline showed that MDR K. pneumoniae and E. coli, including those that were carbapenem resistant, were susceptible more than 90% of the time. A limited number of patients have been treated with tigecycline, but the FDA has approved it in certain cases with synergies of other drugs. The limited number of patients indicates that more trials are needed to determine the overall clinical effectiveness. Although tigecycline is one of the first lines of defense against carbapenemase-producing isolates, negative clinical outcomes with tigecycline have occurred. Both urinary tract and primary blood infections can make tigecycline ineffective, because it has limited penetration and rapid tissue diffusion after being intravenously infused, respectively.
== History == Studies conducted in the 1970s found that a series of N-formylmethionine-containing oligopeptides, including the most potent and best known member of this series, N-Formylmethionine-leucyl-phenylalanine (FMLP or fMet-Leu-Phe), stimulated rabbit and human neutrophils by an apparent receptor-dependent mechanism to migrate in a directional pattern in classical laboratory assays of chemotaxis. Since these oligopeptides were produced by bacteria or synthetic analogs of such products, it was suggested that the N-formyl oligopeptides are important chemotactic factors and their receptors are important chemotactic factor receptors that act respectively as signaling and signal-recognizing elements to initiate Inflammation responses in order to defend against bacterial invasion. Further studies cloned a receptor for these N-formyl oligopeptides, FPR1. Two receptors where thereafter discovered and named FPR2 and FPR3 based on the similarity of their genes' predicted amino acid sequence to that of FPR1 rather than on any ability to bind or be activated by the formyl oligopeptides. The latter two receptors were subsequently found to have very different specificities for the formyl oligopeptides and very different functions than those for FPR1. FPR1 is the premiere receptor for the pro-inflammatory actions of formyl peptides.
Female breasts were also prominent in Minoan art in the form of the famous Snake Goddess statuettes, and a few other pieces, though most female breasts are covered. In Ancient Greece there were several cults worshipping the "Kourotrophos", the suckling mother, represented by goddesses such as Gaia, Hera and Artemis. The worship of deities symbolized by the female breast in Greece became less common during the first millennium. The popular adoration of female goddesses decreased significantly during the rise of the Greek city states, a legacy which was passed on to the later Roman Empire. During the middle of the first millennium BC, Greek culture experienced a gradual change in the perception of female breasts. Women in art were covered in clothing from the neck down, including female goddesses like Athena, the patron of Athens who represented heroic endeavor. There were exceptions: Aphrodite, the goddess of love, was more frequently portrayed fully nude, though in postures that were intended to portray shyness or modesty, a portrayal that has been compared to modern pin ups by historian Marilyn Yalom. Although nude men were depicted standing upright, most depictions of female nudity in Greek art occurred "usually with drapery near at hand and with a forward-bending, self-protecting posture". A popular legend at the time was of the Amazons, a tribe of fierce female warriors who socialized with men only for procreation and even removed one breast to become better warriors (the idea being that the right breast would interfere with the operation of a bow and arrow).
=== Mortality === Obesity is one of the leading preventable causes of death worldwide. The mortality risk is lowest at a BMI of 20–25 kg/m2 in non-smokers and at 24–27 kg/m2 in current smokers, with risk increasing along with changes in either direction. This appears to apply in at least four continents. Other research suggests that the association of BMI and waist circumference with mortality is U- or J-shaped, while the association between waist-to-hip ratio and waist-to-height ratio with mortality is more positive. In Asians the risk of negative health effects begins to increase between 22 and 25 kg/m2. In 2021, the World Health Organization estimated that obesity caused at least 2.8 million deaths annually. On average, obesity reduces life expectancy by six to seven years, a BMI of 30–35 kg/m2 reduces life expectancy by two to four years, while severe obesity (BMI ≥ 40 kg/m2) reduces life expectancy by ten years.
Sources: en.wikipedia.org
On 1 May 1999 Pudzianowski entered his first Strongman competition, held in Płock, Poland. He achieved his first major success at the international level at the 2000 World's Strongest Man contest where he finished fourth in his first WSM competition. Due to his prison sentence, he did not return for the 2001 competition. Pudzianowski returned at the 2002 World's Strongest Man and won his first title. He retained his title at the 2003 World's Strongest Man with an event to spare, winning by the largest margin ever achieved in the competition; across the seven disciplines in the final, he scored a remarkable four first place finishes, two second place finishes and one third place finish, resulting in the points margin between first and second (20) being greater than the margin between second and ninth (18). British strongman Laurence Shahlaei has since called this performance the most dominant victory ever seen at a World's Strongest Man event. In March 2004, he also became the Strongman Super Series World Champion. He initially finished third in the 2004 World's Strongest Man but was later disqualified for breaching the governing body's Strongman Health Policy. He was forced to return his prize money, stripped of the International Federation of Strength Athletes points from the event, and received a one-year ban from competition. Pudzianowski did not dispute his banned substance violation and waived his right to have his stool sample verified. In 2005, he made his return to World's Strongest Man event.
== Neuroendocrine tumors (209–209) == 209 Neuroendocrine tumors 209.0 Malignant carcinoid tumors of the small intestine 209.1 Malignant carcinoid tumors of the appendix, large intestine, and rectum 209.2 Malignant carcinoid tumors of other and unspecified sites 209.3 Malignant poorly differentiated neuroendocrine carcinoma 209.4 Benign carcinoid tumors of the small intestine 209.5 Benign carcinoid tumors of the appendix, large intestine, and rectum 209.6 Benign carcinoid tumors of other and unspecified sites
=== Concentration quotients === In aqueous solution, equilibrium constants are usually determined in the presence of an "inert" electrolyte such as sodium nitrate, NaNO3, or potassium perchlorate, KClO4. The ionic strength of a solution is given by
7 June Dan Bullock was the youngest U.S. serviceman to be killed in the war at age 15. Having lied about his age to join the Marine Corps he was killed in a sapper attack at An Hoa Combat Base. Following a rocket and artillery barrage, at 04:30 two battalions of the PAVN 88th Regiment attacked Firebase Crook, but were forced back by gunship fire. PAVN losses were 323 killed without loss among U.S. forces.
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.
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.