If you have been reading about GHK-Cu and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2025-10-09. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
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.
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.
| 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 |
Material described in research and cosmetic supply chains is typically a synthetic peptide supplied as a lyophilized powder. Purity is commonly reported through chromatographic separation, often at 95 percent or higher, while copper content is confirmed by separate elemental analysis. Batch variation in color and solubility can reflect residual counter-ions, moisture, or partial oxidation of the peptide. Because the complex is not a single regulatory entity, specifications differ between suppliers and are not standardized internationally.
GHK-Cu is a coordination complex formed between the tripeptide glycyl-L-histidyl-L-lysine and a copper(II) ion. The peptide binds copper through its histidine imidazole nitrogen, its terminal amino group, and a deprotonated amide nitrogen, creating a stable chelate ring. The resulting complex carries a distinctive blue to blue-violet color, which arises from copper d-d electronic transitions. In the solid state it is usually handled as a powder, while in solution the complex can dissociate and re-form depending on pH and competing ligands. The name copper tripeptide-1 is widely used in ingredient listings.
The tripeptide was first isolated from a human plasma filtrate in 1973 during studies of tissue repair factors. Later work detected the free peptide and its copper complex in saliva, urine, and wound fluid, suggesting a natural role in tissue remodeling. Plasma concentrations reported in early literature decline with age, a pattern often cited in discussions of skin aging. Whether these endogenous levels are directly functional or largely incidental remains an open question. The peptide sequence is conserved across mammalian species.
The peptide sequence places a histidine in the middle, and this residue dominates metal binding. Copper(II) coordinates through the imidazole nitrogen of histidine and the terminal amino group, forming a stable chelate ring system. Loss of the copper ion leaves the free tripeptide, which has different solubility and reactivity. This structural detail matters because assays that measure only the peptide backbone can miss whether copper is still bound to it.
Several names circulate for the same material, which complicates literature searches. Cosmetic ingredient lists often use copper tripeptide-1, while older biochemistry papers use glycyl-L-histidyl-lysine or its abbreviation GHK. The copper complex is sometimes written as GHK-Cu(II) to make the oxidation state explicit. Terminology is not fully standardized, so matching a compound across sources requires attention to the exact sequence, the counterion, and the stated copper content. Reviews that compare studies must account for these naming differences before drawing conclusions.
GHK-Cu is the copper(II) complex of the tripeptide glycyl-L-histidyl-L-lysine, a short sequence of three amino acids. The peptide was first isolated from human plasma in 1973 during research on factors that influence tissue repair in liver. Its ability to bind copper ions became a central point of interest because the metal changes the peptide's chemistry and its behaviour in laboratory systems. Today the compound appears in cosmetic formulations, cell-culture studies, and biochemistry literature under several names.
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.
Stability of GHK-Cu in solution depends on pH, temperature, buffer composition, and oxygen exposure. The copper center can undergo reduction or dissociation, especially in the presence of strong metal chelators such as EDTA. Aqueous solutions are often prepared fresh or stored frozen to limit degradation. Lyophilized solid is more stable than liquid formulations, but it can absorb moisture and should be kept dry. Light exposure may also affect copper complexes, though the effect is often modest.
Purity assessment typically involves high-performance liquid chromatography for the peptide and atomic spectroscopy for copper content. The ratio of copper to peptide is a key quality parameter; a value near one indicates proper stoichiometry. Impurities can include free peptide, copper salts, and truncated sequences from synthesis. Because the complex is dynamic, sample preparation and mobile-phase conditions can shift the observed species. Reported purity values therefore depend on the analytical method and should be interpreted with that context.
At the age of 16, Tolkien met Edith Mary Bratt, who was three years his senior, when he and his brother Hilary moved into the boarding house where she lived in Duchess Road, Edgbaston. According to Humphrey Carpenter, "Edith and Ronald took to frequenting Birmingham teashops, especially one which had a balcony overlooking the pavement. There they would sit and throw sugarlumps into the hats of passers-by, moving to the next table when the sugar bowl was empty. ... With two people of their personalities and in their position, romance was bound to flourish. Both were orphans in need of affection, and they found that they could give it to each other. During the summer of 1909, they decided that they were in love." His guardian, Father Morgan, considered it "altogether unfortunate" that his surrogate son was romantically involved with an older, Protestant woman; Tolkien wrote that the combined tensions contributed to his having "muffed [his] exams". Morgan prohibited him from meeting, talking to, or even corresponding with Edith until he was 21. Tolkien obeyed this prohibition to the letter, with one notable early exception, over which Father Morgan threatened to cut short his university career if he did not stop. On the evening of his 21st birthday Tolkien wrote to Edith, who was living with a family friend named C. H. Jessop in Cheltenham. He declared that he had never ceased to love her, and asked her to marry him. Edith replied that she had already accepted the proposal of George Field, the brother of one of her closest school friends.
== Linea alba == The linea alba is a white, fibrous band that is made of the bilateral rectus sheaths that join at the anterior midline of the body. These enclose the rectus abdominis muscles (a pair of long, linear muscles, commonly called the “sit-up” muscles) that originate at the pubic crest and pubic symphysis, and extend the length of the body’s trunk. Each muscle is segmented by three transverse bands of collagen fibers called the tendinous intersections. This results in the look of “six-pack abs,” as each segment hypertrophies on individuals at the gym who do many sit-ups.
Self-assembly is a scalable and parallel process which can involve large numbers of components in a short timeframe. Can result in structural dimensions across orders of magnitude, from nanoscale to macroscale. Is relatively inexpensive compared to the top-down assembly approach, which often consumes large amounts of finite resources. Natural processes that drive self-assembly tend to be highly reproducible. The existence of life is strongly dependent on the reproducibility of self-assembly. Challenges There exist several outstanding challenges in self-assembly, due to a variety of competing factors. Currently self-assembly is difficult to control on large scales, and to be widely applied we will need to ensure high degrees of reproducibility at these scales. The fundamental thermodynamic and kinetic mechanisms of self-assembly are poorly understood - the basic principles of atomistic and macroscale processes can be significantly different than those for nanostructures. Concepts related to thermal motion and capillary action influence equilibrium timescales and kinetic rates that are not well defined in self-assembling systems. Top-down vs bottom-up synthesis
=== Non-human orthologs === Cathelicidin peptides have been found in humans, monkeys, mice, rats, rabbits, guinea pigs, pandas, pigs, cattle, frogs, sheep, goats, chickens, horses and wallabies. Antibodies to the human LL-37/hCAP-18 have been used to find cathelicidin-like compounds in a marsupial. About 30 cathelicidin family members have been described in mammals, with only one (LL-37) found in humans. Currently identified cathelicidin peptides include the following:
ion channel A type of transmembrane protein complex which forms an aqueous pore or channel spanning the lipid bilayer of a membrane, through which specific inorganic, electrically charged ions can diffuse down their electrochemical gradients.
Sources: en.wikipedia.org
Nixon and Kissinger played a "good cop-bad cop" routine with Dobrynin, with Nixon acting the part of the petulant president at the end of his patience with North Vietnam, while Kissinger acted as the reasonable diplomat anxious to improve relations with the Soviet Union, saying to Dobrynin in May 1969 that Nixon would "escalate the war" if the Soviet Union "didn't produce a settlement" in Vietnam. At another meeting in 1969, Kissinger warned Dobrynin that "the train has just left the station and is now headed down the track", saying the Soviet Union better start pressuring North Vietnam now before Nixon did something truly reckless and dangerous. The attempt at "linkage" failed as the Soviet Union did not pressure North Vietnam and instead Dobrynin told Kissinger that the Soviets wanted better relations with the United States regardless of the Vietnam War. After the failure of the "linkage" attempt, Nixon became more open to the alternative strategy suggested by the Defense Secretary Melvin Laird who argued that the burden of the war should be shifted to the South Vietnamese, which was initially called "de-Americanization" and which Laird renamed Vietnamization because it sounded better.
=== Test strip process === The niacin test strip is typically composed of potassium thiocyanate, chloramine-T, citric acid, and 4-Aminosalicylic acid. In the presence of citric acid, chloramine-T and potassium thiocyanate will react to form cyanogen chloride. This chemical will break apart the pyridine ring of niacin to produce y-carboxy glutaconic aldehyde and joins an aromatic amine to form a yellow color.
==== United Kingdom ==== Phenazepam is a class C drug in the UK. The UK Home Office banned importation of phenazepam on Friday 22 July 2011 while it drafted legislation, released in January 2012 to become law at the end of March 2012. The bill was quashed following advice from the ACMD as it included two non-abusable steroids. There was a new discussion about its fate on April 23, 2012, where it was decided that the bill would be rewritten and phenazepam would still be banned. It was eventually banned on June 13, 2012 as a class C, schedule II drug.
=== Materials === Material selection is an essential aspect of producing a scaffold. The materials utilized can be natural or synthetic and can be biodegradable or non-biodegradable. Additionally, they must be biocompatible, meaning that they do not cause any adverse effects to cells. Silicone, for example, is a synthetic, non-biodegradable material commonly used as a drug delivery material, while gelatin is a biodegradable, natural material commonly used in cell-culture scaffolds The material needed for each application is different, and dependent on the desired mechanical properties of the material. Tissue engineering of long bone defects for example, will require a rigid scaffold with a compressive strength similar to that of cortical bone (100-150 MPa), which is much higher compared to a scaffold for skin regeneration. There are a few versatile synthetic materials used for many different scaffold applications. One commonly used materials is polylactic acid (PLA), a polyester which degrades within the human body to form lactic acid, a naturally occurring chemical which is easily removed from the body. Similar materials are polyglycolic acid (PGA) and polycaprolactone (PCL); their degradation mechanism is similar to that of PLA, but PCL degrades slower and PGA degrades faster. PLA is commonly combined with PGA to create poly-lactic-co-glycolic acid (PLGA). This is useful because the degradation of PLGA can be tailored by altering the weight percentages of PLA and PGA: More PLA – slower degradation, more PGA – faster degradation.
== History == Lactobacillus delbrueckii subsp. bulgaricus was first identified in 1905 by Stamen Grigorov, who named it Bacillus bulgaricus. Ilya Metchnikoff, a professor at the Pasteur Institute in Paris, researched the relationship between the longevity of Bulgarians and their consumption of yogurt. He had the idea that aging is caused by putrefactive activity, or proteolysis, by microbes that produce toxic substances in the intestine. Proteolytic bacteria such as clostridia, which are part of the normal intestinal flora, produce toxic substances including phenols, ammonia and indols by digestion of proteins. These compounds are responsible for what Metchnikoff called intestinal auto-intoxication, which, according to him, was the cause of the physical changes associated with old age. It was already known at that time that fermentation with lactic acid bacteria inhibits the deterioration of milk because of its low pH. Metchnikoff's research also noted that rural populations in Southeastern Europe and the Russian steppes daily consume milk fermented with lactic acid bacteria and live relatively longer than other populations. Based on these data Metchnikoff proposed that consumption of fermented milk seeds the intestine with harmless lactic acid bacteria increasing intestinal acidity and suppressing the growth of proteolytic bacteria. His results were questioned after a 1920 study showed that the bacterium could not survive in the human intestines, but the idea nevertheless started the research into actually useful probiotics.
Sources: en.wikipedia.org
=== First endosymbiosis === Eukaryotic algae are polyphyletic thus their origin cannot be traced back to a single hypothetical common ancestor. It is thought that they came into existence when photosynthetic coccoid cyanobacteria got phagocytized by a unicellular heterotrophic eukaryote (a protist), giving rise to double-membranous primary plastids. Such symbiogenic events (primary symbiogenesis) are believed to have occurred more than 1.5 billion years ago during the Calymmian period, early in Boring Billion, but it is difficult to track the key events because of so much time gap. Primary symbiogenesis gave rise to three divisions of archaeplastids, namely the Viridiplantae (green algae and later plants), Rhodophyta (red algae) and Glaucophyta ("grey algae"), whose plastids further spread into other protist lineages through eukaryote-eukaryote predation, engulfments and subsequent endosymbioses (secondary and tertiary symbiogenesis). This process of serial cell "capture" and "enslavement" explains the diversity of photosynthetic eukaryotes. The oldest undisputed fossil evidence of eukaryotic algae is Bangiomorpha pubescens, a red alga found in rocks around 1047 million years old.
== γ-Lipotropin == γ-lipotropin is the amino-terminal peptide fragment of β-lipotropin. In humans, it has 56 amino acids. Gamma lipotropin is identical to the first 56 amino acid sequences of β-lipotropin. It can be cleaved to β-melanocyte stimulating hormone. In sheep, gamma-lipotropic hormone is a 58-amino-acid long pituitary polypeptide formed from the first 58 residues of beta-lipotropic hormone. The carboxyl-terminal of gamma-lipotropic hormone is identical to the structure of beta-melanophore-stimulating hormone.
== Incidence == Unfortunately, there is no absolute definition that describes the incidence of drug-induced QT prolongation, as most data is obtained from case reports or small observational studies. Although QT interval prolongation is one of the most common reasons for drug withdrawal from the market, the overall incidence of drug-induced QT prolongation is difficult to estimate. One study in France estimated that between 5-7% of reports of ventricular tachycardia, ventricular fibrillation, or sudden cardiac death were in fact due to drug-induced QT prolongation and torsades de pointes. An observational study from the Netherlands showed that 3.1% of patients who experienced sudden cardiac death were also using a QT-prolonging drug.
==== Monazite compositional mapping ==== Monazite grains which show useful relationships with microtextures or host minerals are selected for compositional mapping. Major elemental and sometimes trace elemental maps are created at high magnification by electron microprobe X-ray mapping to show compositional zonation patterns. Maps of elemental Y, Th, Pb, U have proven useful in identifying compositional domains in monazite.
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 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.