Everything below concerns tripeptide sequence. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2025-11-14. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Peptide sequence | Gly-His-Lys | Three amino acids, histidine in the middle |
| Complex formula | C14H22CuN6O4 | One copper(II) ion per peptide |
| Molar mass (complex) | approx. 402.9 g/mol | Depends on counterion and hydration state |
| Appearance | Blue to blue-violet solid | Colour arises from copper coordination |
| Common synonyms | Copper tripeptide-1, GHK-Cu | Naming varies between disciplines |
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 compound was first isolated from human plasma by the biochemist Loren Pickart in 1973. Early work identified it as a factor that altered the behavior of cultured liver cells, and later studies linked it to connective tissue and wound-related processes. Reported plasma concentrations fall markedly between roughly age twenty and age sixty, a pattern that generated interest in copper peptide biology. Whether that decline has functional consequences remains an open question, because differences observed across age groups do not by themselves establish causation. Research interest later expanded into cosmetic and tissue-culture settings.
Mechanistic accounts focus on how the complex delivers copper and how the released peptide interacts with the extracellular matrix. Copper is an essential cofactor for lysyl oxidase and other enzymes involved in collagen and elastin cross-linking, and GHK is one of several peptides able to carry the metal. Reported effects include altered gene expression in fibroblasts and changes in matrix metalloproteinase activity, although many of these findings come from cell culture rather than whole organisms. The relative contribution of the peptide backbone, the copper ion, and downstream copper metabolism is not fully resolved.
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.
"At night, in our rooms, we can't sleep. We twitch and dance and jig about as though we were doing St Vitus's Dance..." "There's less flesh on our bodies than on a skeleton," Francis said. Francis Pélissier said much later: "Londres was a famous reporter but he didn't know about cycling. We kidded him a bit with our cocaine and our pills. Even so, the Tour de France in 1924 was no picnic." The acceptance of drug-taking in the Tour de France was so complete by 1930, when the race changed to national teams that were to be paid for by the organisers, that the rule book distributed to riders by the organiser, Henri Desgrange, reminded them that drugs were not among items with which they would be provided. The use of Pot Belge by road cyclists in continental Europe exemplifies a cross-over between recreational and performance-enhancing abuse of drugs by sportsman.
Although genes were known to exist on chromosomes, chromosomes are composed of both protein and DNA, and scientists did not know which of the two was responsible for inheritance. In 1928, Frederick Griffith discovered the phenomenon of transformation: dead bacteria could transfer genetic material to "transform" other still-living bacteria. Sixteen years later, in 1944, the Avery–MacLeod–McCarty experiment identified DNA as the molecule responsible for transformation. The role of the nucleus as the repository of genetic information in eukaryotes had been established by Hämmerling in 1943 in his work on the single celled alga Acetabularia. The Hershey–Chase experiment in 1952 confirmed that DNA (rather than protein) is the genetic material of the viruses that infect bacteria, providing further evidence that DNA is the molecule responsible for inheritance. James Watson and Francis Crick determined the structure of DNA in 1953, using the X-ray crystallography work of Rosalind Franklin and Maurice Wilkins that indicated DNA has a helical structure (i.e., shaped like a corkscrew). Their double-helix model had two strands of DNA with the nucleotides pointing inward, each matching a complementary nucleotide on the other strand to form what look like rungs on a twisted ladder. This structure showed that genetic information exists in the sequence of nucleotides on each strand of DNA. The structure also suggested a simple method for replication: if the strands are separated, new partner strands can be reconstructed for each based on the sequence of the old strand.
Most troops fighting for the British army came from Britain, and a significant number came from other parts of its Empire. These countries had internal disputes over whether they should remain tied to London, or have independence, which carried over into the debate around sending forces to assist the war. Though not independent on foreign affairs, these countries did have local say over how much support to provide, and how it was provided. Australia, Canada, New Zealand, and Rhodesia all sent volunteers to aid the UK. Troops were also raised to fight with the British from the Cape Colony and Natal. Some Boer fighters, such as Smuts and Botha, were British subjects as they came from the Cape Colony and Colony of Natal, respectively. There were many volunteers from the Empire who were not selected for the official contingents and travelled privately to form private units, such as the Canadian Scouts and Doyle's Australian Scouts. There were European volunteer units from British India and British Ceylon, though the British refused offers of non-white troops from the Empire. Some Cape Coloureds volunteered early in the war, but later some were effectively conscripted and kept in segregated units. As a community, they received little reward for their services. The war set the pattern for the Empire's involvement in the two World Wars. Specially raised units, consisting of volunteers, were dispatched overseas to serve with forces from elsewhere in the Empire.
RCH=CH2 + H2 + CO → RCH2−CH2CHO Rh-based hydroformylation underpins the industrial production of products as diverse as detergents, fragrances, and some drugs. Rhodium based catalysts have 1000 to 10000 times higher activity for hydroformylation than cheaper cobalt carbonyl-based catalysts, allowing reactions at lower temperatures and pressures. Rhodium is also known to catalyze many reactions involving hydrogen gas and hydrosilanes. These include hydrogenations and hydrosilylations of alkenes. Rhodium metal, but not rhodium complexes, catalyzes the hydrogenation of benzene to cyclohexane.
Sources: en.wikipedia.org
=== Communities === Scabies is endemic in many developing countries, and it tends to be particularly prevalent in rural and remote areas. In such settings, community-wide control strategies are required to reduce the rate of disease, as treatment of only individuals is ineffective due to the high rate of reinfection. Large-scale mass drug administration strategies may be required where coordinated interventions aim to treat whole communities in one concerted effort. Although such strategies have shown to be able to reduce the burden of scabies in these kinds of communities, debate remains about the best strategy to adopt, including the choice of drug. The resources required to implement such large-scale interventions in a cost-effective and sustainable way are significant. Furthermore, since endemic scabies is largely restricted to poor and remote areas, it is a public health issue that has not attracted much attention from policymakers and international donors.
As well as being extracted from nuclear waste, radioisotopes can be produced deliberately with nuclear reactors, exploiting the high flux of neutrons present. These neutrons activate elements placed within the reactor. A typical product from a nuclear reactor is iridium-192, from activation of iridium targets. The elements that have a large propensity to take up neutrons in the reactor are said to have a high neutron cross-section, but even at low cross-sections this process is generally economical. Particle accelerators such as cyclotrons accelerate particles to bombard a target to produce radionuclides. Cyclotrons accelerate (most often) protons at a target to produce positron-emitting radionuclides, e.g. fluorine-18. Radionuclide generators, standard for many medical isotopes, contain a parent radionuclide that decays to produce a shorter-lived radioactive daughter. A typical example is the technetium-99m generator, which employs molybdenum-99 produced in a reactor.
AMPK probably also plays a role in increased peripheral insulin sensitivity, as metformin administration increases AMPK activity in skeletal muscle. AMPK is known to cause GLUT4 deployment to the plasma membrane, resulting in insulin-independent glucose uptake. Some metabolic actions of metformin do appear to occur by AMPK-independent mechanisms, however, AMPK likely has a modest overall effect and its activity is not likely to directly decrease gluconeogenesis in the liver. Metformin has indirect antiandrogenic effects in women with insulin resistance, such as those with PCOS, due to its beneficial effects on insulin sensitivity. It may reduce testosterone levels in such women by as much as 50%. A Cochrane review, though, found that metformin was only slightly effective for decreasing androgen levels in women with PCOS. Metformin also has significant effects on the gut microbiome, such as its effect on increasing agmatine production by gut bacteria, but the relative importance of this mechanism compared to other mechanisms is uncertain. Due to its effect on GLUT4 and AMPK, metformin has been described as an exercise mimetic.
Pyruvate is taken up by a specific, low Km transporter to bring it into the mitochondrial matrix for oxidation by the pyruvate dehydrogenase complex. The phosphate carrier (PiC) mediates the electroneutral exchange (antiport) of phosphate (H2PO−4; Pi) for OH− or symport of phosphate and protons (H+) across the inner membrane, and the driving force for moving phosphate ions into the mitochondria is the proton motive force. The ATP-ADP translocase (also called adenine nucleotide translocase, ANT) is an antiporter and exchanges ADP and ATP across the inner membrane. The driving force is due to the ATP (−4) having a more negative charge than the ADP (−3), and thus it dissipates some of the electrical component of the proton electrochemical gradient. The outcome of these transport processes using the proton electrochemical gradient is that more than 3 H+ are needed to make 1 ATP. Obviously, this reduces the theoretical efficiency of the whole process and the likely maximum is closer to 28–30 ATP molecules. In practice the efficiency may be even lower because the inner membrane of the mitochondria is slightly leaky to protons. Other factors may also dissipate the proton gradient creating an apparently leaky mitochondria. An uncoupling protein known as thermogenin is expressed in some cell types and is a channel that can transport protons. When this protein is active in the inner membrane it short circuits the coupling between the electron transport chain and ATP synthesis. The potential energy from the proton gradient is not used to make ATP but generates heat.
where Ra, Rb, Rc, Rd are the radii in the circles externally tangent to the sides a, b, c, d respectively and the extensions of the adjacent two sides for each side. Several more characterizations are known in the four subtriangles formed by the diagonals.
Sources: en.wikipedia.org
=== Nitric oxide === Nitric oxide (NO) is a major source of immunomodulation in rodents, and is produced by enzyme nitric oxide synthetase type 2 (NOS2) in the alveolar macrophage. NO inhibits tyrosine phosphorylation of the kinases involved in production of the interleukin-2 (IL-2) receptor, the expression of which is fundamental for T cell proliferation. In humans, however, NOS2 activity has been difficult to verify. There are two explanations for the lack of responsiveness in the promoter of human inducible nitric oxide synthetase (iNOS) to NO activation by lipopolysaccharides (LPS) + interferon gamma (IFNγ). The first is that there are various inactivating nucleotide variations in the human counterpart of the enhancer element that regulates LPS/IFNγ induced expression of the mouse NOS2 gene. The second is because of the absence of a nuclear factor in human macrophages that is required for optimum expression of gene NOS2 (LPS-inducible nuclear factor-kappa B/Rel complex). It is assumed that the difficulty in verifying NOS2 is due to a much more tightly controlled expression in human AMs as compared to that in the rodent AMs. NOS2 is part of an autoregulatory feedback loop, wherein an allergen or provoker stimulates inflammatory cytokine production, which in turn stimulates NO production, and NO down-regulates cytokine production.
is hundreds of milliseconds. This effect is often described using modified Bloch equations that include terms for radiation damping alongside the conventional relaxation terms. The longitudinal relaxation time of radiation damping (
In addition to the ring scissions (cleavages), expansions and contractions (cleavage and reclosing to a larger or smaller rings)—all variations in the carbon-carbon bond framework—steroids can also vary:
Loss-of-function mutations, also called inactivating mutations, result in the gene product having less or no function (being partially or wholly inactivated). When the allele has a complete loss of function (null allele), it is often called an amorph or amorphic mutation in Muller's morphs schema. Phenotypes associated with such mutations are most often recessive. Exceptions are when the organism is haploid, or when the reduced dosage of a normal gene product is not enough for a normal phenotype (this is called haploinsufficiency). Examples of diseases caused by a loss-of-function mutation include Gitelman syndrome and cystic fibrosis. Gain-of-function mutations also called activating mutations, change the gene product such that its effect gets stronger (enhanced activation) or even is superseded by a different and abnormal function. When the new allele is created, a heterozygote containing the newly created allele as well as the original will express the new allele; genetically this defines the mutations as dominant phenotypes. Several of Muller's morphs correspond to the gain of function, including hypermorph (increased gene expression) and neomorph (novel function). Dominant negative mutations (also called anti-morphic mutations) have an altered gene product that acts antagonistically to the wild-type allele. These mutations usually result in an altered molecular function (often inactive) and are characterized by a dominant or semi-dominant phenotype.
Sources: en.wikipedia.org
The peptide is glycyl-L-histidyl-L-lysine, a three-amino-acid sequence commonly abbreviated GHK. It binds a single copper(II) ion under typical laboratory conditions. The free peptide and the copper complex are separate chemical species with different properties.
The sequence was identified in human plasma in 1973. Early work examined its presence in blood and its proposed role in tissue repair. The copper-binding property was characterized afterward and became the focus of much later research.
The tripeptide has been measured in human plasma and other biological fluids. Whether it circulates mainly as the copper complex or as the free peptide remains an open question. Natural concentrations are low and difficult to measure reliably.
GHK-Cu is a complex of the tripeptide glycyl-L-histidyl-L-lysine with copper(II). The peptide binds copper through its histidine residue and neighboring amide nitrogens, forming a stable coordination compound. It is studied as a research chemical and used in some cosmetic formulations.