A practical reference on extracellular matrix: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-05-06. Anything still debated is marked as such rather than presented as settled.
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.
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.
GHK-Cu is a coordination complex formed between the tripeptide glycyl-L-histidyl-L-lysine and a copper(II) ion. The peptide sequence is often abbreviated Gly-His-Lys, and the copper is bound through the histidine imidazole nitrogen and adjacent peptide nitrogens. The complex is frequently described as a 1:1 peptide-to-copper species. It occurs naturally in human plasma, saliva, and urine at low concentrations. Its endogenous levels have been reported to decline with age, although the precise physiological role of that change remains an open question.
| 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 |
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.
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.
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.
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.
Identity and purity are usually assessed with reversed-phase high-performance liquid chromatography, often paired with mass spectrometry. Copper content is measured separately by techniques such as inductively coupled plasma mass spectrometry or atomic absorption. Amino acid analysis confirms the peptide sequence after hydrolysis. Because the metal and the peptide can be quantified independently, a complete certificate of analysis normally reports both values rather than a single purity figure. This separation of measurements is important when comparing suppliers.
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.
Copper takes part in redox chemistry, and the same property that makes it useful in enzymes can generate reactive oxygen species when the ion is loosely bound. GHK chelates copper through imidazole, amino, and amide nitrogen donors, which reduces the amount of free copper in solution. Whether that chelation is protective, neutral, or harmful in a given tissue is not settled. Laboratory assays report both antioxidant and pro-oxidant behavior, depending on the conditions and the readout used.
Published work on GHK-Cu is dominated by in vitro experiments and small animal studies. Human trials tend to be short and small, with endpoints such as skin appearance rather than clinical outcomes. Review articles often summarize the same underlying laboratory findings, which can make the evidence base look broader than it is. Several basic questions remain open: the concentration of the intact complex in human tissue, the route by which it crosses the skin barrier, and whether effects seen in culture produce measurable changes in people.
Laboratory studies describe GHK-Cu as a source of copper that cells can take up, with reported effects on collagen, elastin, and glycosaminoglycan synthesis in cultured fibroblasts. The peptide also appears in wound-repair research, where it is linked to the activity of matrix metalloproteinases and their inhibitors. These observations come largely from cell and animal models. How directly the complex controls any single pathway in intact human skin remains an open question, and reported effects depend on concentration, vehicle, and exposure time.
=== Industrial production of chemicals === The dominant use for sulfuric acid is in the "wet method" for the production of phosphoric acid, used for manufacture of phosphate fertilizers. In this method, phosphate rock is used, and more than 100 million tonnes are processed annually. This raw material is shown below as fluorapatite, though the exact composition may vary. This is treated with 93% sulfuric acid to produce calcium sulfate, hydrogen fluoride (HF) and phosphoric acid. The HF is removed as hydrofluoric acid. The overall process can be represented as:
Plant ecology is the science of the functional relationships between plants and their habitats – the environments where they complete their life cycles. Plant ecologists study the composition of local and regional floras, their biodiversity, genetic diversity and fitness, the adaptation of plants to their environment, and their competitive or mutualistic interactions with other species. Some ecologists even rely on empirical data from indigenous people that is gathered by ethnobotanists. This information can relay a great deal of information on how the land once was, thousands of years ago, and how it has changed over that time. The goals of plant ecology are to understand the causes of their distribution patterns, productivity, environmental impact, evolution, and responses to environmental change. Plants depend on certain edaphic (soil) and climatic factors in their environment but can modify these factors too. For example, they can change their environment's albedo, increase runoff interception, stabilise mineral soils and develop their organic content, and affect local temperature. Plants compete with other organisms in their ecosystem for resources. They interact with their neighbours at a variety of spatial scales in groups, populations and communities that collectively constitute vegetation. Regions with characteristic vegetation types and dominant plants as well as similar abiotic and biotic factors, climate, and geography make up biomes like tundra or tropical rainforest.
== Personal life == On 17 October 2009 McVeigh married his longtime girlfriend, Leanne Tucker. They have a daughter, Ariana, born in March 2011. Mark also had a niece, Luella (the daughter of Sydney's Jarrad McVeigh), born on 25 July 2011 but she died from heart complications barely a month later. Following Essendon's seven-point victory over Port Adelaide, its first over the side since 2004, Mark 'blew a kiss towards to the heavens' in her memory. Essendon's players wore black armbands in the match.
Distal stabilisation of muscles is often performed. This allows effective muscle contraction which reduces atrophy, allows functional use of the stump and maintains soft tissue coverage of the remnant bone. The preferred stabilisation technique is myodesis where the muscle is attached to the bone or its periosteum. In joint disarticulation amputations tenodesis may be used where the muscle tendon is attached to the bone. Muscles are attached under similar tension to normal physiological conditions. An experimental technique known as the "Ewing amputation" aims to improve post-amputation proprioception. Another technique with similar goals, which has been tested in a clinical trial, is Agonist-antagonist Myoneural Interface (AMI). In 1920, Dr. Janos Ertl Sr. of Hungary, developed the Ertl procedure in order to return a high number of amputees to the workforce. The Ertl technique, an osteomyoplastic procedure for transtibial amputation, can be used to create a highly functional residual limb. Creation of a tibiofibular bone bridge provides a stable, broad tibiofibular articulation that may be capable of some distal weight bearing. Several different modified techniques and fibular bridge fixation methods have been used; however, no current evidence exists regarding comparison of the different techniques.
Sources: en.wikipedia.org
=== Electronic spectrum === Electrons propagating through the graphene honeycomb lattice effectively lose their mass, producing quasi-particles described by a 2D analogue of the Dirac equation rather than the Schrödinger equation for spin-1/2 particles.
== In culture == Spider webs play a crucial role in the 1952 children's novel Charlotte's Web. Webs are also featured in many other cultural depictions of spiders. In films, illustration, and other visual arts, spider webs may be used to readily suggest a "spooky" atmosphere, or imply neglect or the passage of time. Artificial "spider webs" are a common element of Halloween decorations. Spider webs are a common image in tattoo art, often symbolizing long periods of time spent in prison, or used simply to fill gaps between other images. Some observers believe that a small spider is depicted on the United States one-dollar bill, in the upper-right corner of the front side (obverse), perched on the shield surrounding the number "1". This perception is enhanced by the resemblance of the background image of intertwining fine lines to a stylized spider web. However, other observers believe the figure is an owl. The World Wide Web is thus named because of its tangled and interlaced structure, said to resemble that of a spider web. Itsy Bitsy Spider is a popular nursery rhyme about the adventures of a spider. Artificial spider webs are used by the superhero Spider-Man to restrain enemies and to make ropes on which to swing between buildings as quick transportation. Some incarnations of the character, such as the version in the Sam Raimi film trilogy and Spider-Man 2099, are shown to be able to produce organic webs. The notable tensile strength of spider webs is often exaggerated in science fiction, often as a plot device to justify the presence of artificially giant spiders.
== Mechanism == NADK phosphorylates NAD+ at the 2’ position of the ribose ring that carries the adenine moiety. It is highly selective for its substrates, NAD and ATP, and does not tolerate modifications either to the phosphoryl acceptor, NAD, or the pyridine moiety of the phosphoryl donor, ATP. NADK also uses metal ions to coordinate the ATP in the active site. In vitro studies with various divalent metal ions have shown that zinc and manganese are preferred over magnesium, while copper and nickel are not accepted by the enzyme at all. A proposed mechanism involves the 2' alcohol oxygen acting as a nucleophile to attack the gamma-phosphoryl of ATP, releasing ADP.
The Transitional National Government (TNG) was established in April–May 2000 at the Somalia National Peace Conference (SNPC) held in Arta, Djibouti. Abdiqasim Salad Hassan was selected as the President of the nation's new Transitional National Government (TNG), an interim administration formed to guide Somalia to its third permanent republican government. The TNG's internal problems led to the replacement of the Prime Minister four times in three years, and the administrative body's reported bankruptcy in December 2003. Its mandate ended at the same time. On 10 October 2004, legislators elected Abdullahi Yusuf Ahmed as the first President of the Transitional Federal Government (TFG), the Transitional National Government's successor. The TFG was the second interim administration aiming to restore national institutions to Somalia after the 1991 collapse of the Siad Barre regime and the ensuing civil war. In 2006, the Islamic Courts Union (ICU) assumed control of much of the southern part of the country for 6 months and imposed Shari'a law. Top UN officials have referred to this brief period as a 'Golden era' in the history of Somali politics.
Guzman y Gómez (GYG; , Spanish: [ɡusˈman i ˈɣomes]) is a Mexican-themed casual fast food restaurant chain based in Australia. It serves coffee at some restaurants through the "Cafe Hola" brand which operates 24/7. Guzman y Gomez was established in Sydney in 2006 by Steven Marks and Robert Hazan. It operates over 200 restaurants in Australia, Japan, and Singapore; it formerly had restaurants in the United States. As of 2025, Guzman y Gomez is the sixth-largest fast food chain in Australia by system-wide revenue.
Sources: en.wikipedia.org
==== Solanezumab ==== Solanezumab, an anti-Aβ mAb, targets the N-terminus of Aβ. In Phase I and Phase II of clinical trials, Solanezumab treatment resulted in cerebrospinal fluid elevation of Aβ, thereby showing a reduced concentration of Aβ plaques. Additionally, there are no associated adverse side effects. Phase III clinical trials of Solanezumab brought about significant reduction in cognitive impairment in patients with mild AD, but not in patients with severe AD. However, Aβ concentration did not significantly change, along with other AD biomarkers, including phospho-tau expression, and hippocampal volume. Phase III clinical trials of Solanezumab failed as it did not show effect on cognitive decline in comparison to placebo.
=== Response from political organizations === Health Care Without Harm opposes the use of recombinant bovine growth hormone due to its adverse impacts on animals and potential harm to humans. Oregon Physicians for Social Responsibility recommends buying products from cows not injected with recombinant bovine growth hormone (rBGH or rBST).
China dispatched troops, but did so without notifying Japan, a direct violation of the 1885 agreement and Japan deployed a much larger force to Korea. The Imperial Japanese Army quickly seized Seoul, captured King Gojong, and installed a pro-Japanese government. When China attempted to reinforce its own troops, the Japanese navy fired on and sank the British steamer Kowshing carrying Chinese soldiers, which triggered the First Sino-Japanese War (1894–1895). Following Japan's victory over Qing China with the island of Taiwan ceded to Japan, Japan broke through as an international power with a victory against Imperial Russia in Manchuria (north-eastern China) in the Russo-Japanese War of 1904–1905. The victory by a non-White, Asian power over the largest European great power astonished the Western world. Allied with Britain since the Anglo-Japanese Alliance signed in London on January 30, 1902, Japan joined the Allies in World War I, seizing German-held territory in Qingdao, China and the Pacific in the process, but otherwise remained largely out of the conflict. Following World War I, a weakened Europe left a greater share in international markets to the United States and Japan, which emerged greatly strengthened. Japanese competition made great inroads into hitherto-European-dominated markets in Asia, not only in China, but even in European colonies such as British India and Dutch Indonesia, reflecting the development of the Meiji era. The militarist tendencies accumulated since the Meiji era began Japanese expansionism in Asia.
=== Secondary causes === There are causes for deficiency other than low dietary intake of vitamin A as retinol or carotenes. Adequate dietary protein and caloric energy are needed for a normal rate of synthesis of RBP, without which, retinol cannot be mobilized to leave the liver. Systemic infections can cause transient decreases in RBP synthesis even if protein-calorie malnutrition is absent. Chronic alcohol consumption reduces liver vitamin A storage. Non-alcoholic fatty liver disease (NAFLD), characterized by the accumulation of fat in the liver, is the hepatic manifestation of metabolic syndrome. Liver damage from NAFLD reduces liver storage capacity for retinol and reduces the ability to mobilize liver stores to maintain normal circulating concentration. Vitamin A appears to be involved in the pathogenesis of anemia by diverse biological mechanisms, such as the enhancement of growth and differentiation of erythrocyte progenitor cells, potentiation of immunity to infection, and mobilization of iron stores from tissues.
MHC molecules enable immune system surveillance of the population of protein molecules in a host cell, and greater MHC diversity permits greater diversity of antigen presentation. In 1976, Yamazaki et al demonstrated a sexual selection mate choice by male mice for females of a different MHC. Similar results have been obtained with fish. Some data find lower rates of early pregnancy loss in human couples of dissimilar MHC genes. MHC may be related to mate choice in some human populations, a theory that found support by studies by Ober and colleagues in 1997, as well as by Chaix and colleagues in 2008. However, the latter findings have been controversial. If it exists, the phenomenon might be mediated by olfaction, as MHC phenotype appears strongly involved in the strength and pleasantness of perceived odour of compounds from sweat. Fatty acid esters—such as methyl undecanoate, methyl decanoate, methyl nonanoate, methyl octanoate, and methyl hexanoate—show strong connection to MHC. In 1995, Claus Wedekind found that in a group of female college students who smelled T-shirts worn by male students for two nights (without deodorant, cologne, or scented soaps), the majority of women chose shirts worn by men of dissimilar MHCs, a preference reversed if the women were on oral contraceptives. In 2005 in a group of 58 subjects, women were more indecisive when presented with MHCs like their own, although with oral contraceptives, the women showed no particular preference. No studies show the extent to which odor preference determines mate selection (or vice versa).
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.
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.