Everything below concerns GHK-Cu. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-01-08. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Copper(II) peptide complex | Peptide chain coordinated to a single metal ion |
| CAS number | 89030-95-5 | Indexed for the peptide-copper complex |
| Molecular formula | C14H22CuN6O4 | Approximate formula for a one-to-one complex |
| Appearance | Blue to violet solid | Color from copper d-d transitions |
| Solubility class | Freely soluble in water | Also dispersible in some polar solvents |
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.
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.
After the defeat of Prussia by Napoleon and the subsequent reorganisation of the Prussian state, the academy was merged on 3 August 1811 with the Protestant Viadrina University, previously located in Frankfurt (Oder), and re-established in Breslau as the Königliche Universität zu Breslau – Universitas litterarum Vratislaviensis (in 1911 named the Schlesische Friedrich-Wilhelms-Universität zu Breslau, to honour the founder Frederick William III of Prussia). At first, the conjoint academy had five faculties: philosophy, medicine, law, Protestant theology, and Catholic theology. Connected with the university were three theological seminars, a philological seminar, a seminar for German Philology, another seminar for Romanic and English philology, an historical seminar, a mathematical-physical one, a legal state seminar, and a scientific seminar. From 1842, the university also had a chair of Slavic Studies. The university had twelve different scientific institutes, six clinical centers, and three collections. An agricultural institute with ten teachers and forty-four students, comprising a chemical veterinary institute, a veterinary institute, and a technological institute, was added to the university in 1881. In 1884, the university had 1,481 students in attendance, with a faculty numbering 131.
Chronic consumption of paracetamol is in many cases not of benefit, and may result in abnormal liver function tests, and higher doses may lead to toxicity, including liver failure. Paracetamol poisoning is one of the leading causes of poisoning in high-income countries, and the foremost cause of acute liver failure in many countries. Paracetamol was first made in 1878 by Harmon Northrop Morse or possibly in 1852 by Charles Frédéric Gerhardt. It is the most commonly used medication for pain and fever in both the United States and Europe. It is on the World Health Organization's List of Essential Medicines. Paracetamol is available as a generic medication, with brand names including Tylenol and Panadol, among others. In 2023, it was the 112th most commonly prescribed medication in the United States, with more than 5 million prescriptions.
The FDNY deployed more than 200 units (approximately half of the department) to the World Trade Center. Their efforts were supplemented by off-duty firefighters, Hatzolah, and emergency medical technicians. The NYPD sent its Emergency Service Units and other police personnel and deployed its aviation unit, which determined that helicopter rescues from the towers were not feasible. Numerous police officers of the Port Authority Police Department (PAPD) also participated in rescue efforts. Once on the scene, the FDNY, the NYPD, and the PAPD did not coordinate efforts and performed redundant searches for civilians. As conditions deteriorated, the NYPD aviation unit relayed information to police commanders, who issued orders for personnel to evacuate the towers; most NYPD officers were able to evacuate before the buildings collapsed. With separate command posts set up and incompatible radio communications between the agencies, warnings were not passed along to FDNY commanders. After the first tower collapsed, FDNY commanders issued evacuation warnings. Due to malfunctioning radio repeater systems, many firefighters never heard the evacuation orders. 9-1-1 dispatchers also received information from callers that was not passed along to commanders on the scene.
Sources: en.wikipedia.org
=== Kidney disease and kidney failure === In addition to measures for chronic kidney disease (CKD) of any cause, there is evidence that ACE inhibitors can slow the deterioration of kidney function in Alport syndrome, delaying the need for dialysis or transplantation. The development of proteinuria has been recommended as an indication for commencing treatment. Once kidney failure has developed, patients usually do well on dialysis or with a kidney transplant. Transplantation can rarely be associated with the formation of antibodies to type IV collagen in the donor kidney resulting in progressive graft failure as a result of Goodpasture syndrome ('Alport post-transplant anti-GBM disease'). Gene therapy has been frequently discussed, but delivering it to the podocytes in the glomerulus that normally produce the type IV collagen in the glomerular basement membrane is challenging.
=== Burnup === "Burnup" is a measure of how much energy has been extracted from a given mass of heavy metal in fuel, often expressed (for power reactors) in terms of gigawatt-days per ton of heavy metal. Burnup is an important factor in determining the types and abundances of isotopes produced by a fission reactor. Burnup is distinct from the conversion or breeding ratio. A 2003 study of reduced-moderation water reactor fuel assemblies reported a configuration with an average core burnup of 38.2 GWd/t and a conversion ratio of 1.0, and another with 45 GWd/t and a conversion ratio of 0.97. In the past, breeder-reactor development focused on reactors with low breeding ratios, from 1.01 for the Shippingport Reactor running on thorium fuel and cooled by conventional light water to over 1.2 for the Soviet BN-350 liquid-metal-cooled reactor. Theoretical models of breeders with liquid sodium coolant flowing through tubes inside fuel elements ("tube-in-shell" construction) suggest breeding ratios of at least 1.8 are possible on an industrial scale. The Soviet BR-1 test reactor achieved a breeding ratio of 2.5 under non-commercial conditions.
Friendly AI are machines that have been designed from the beginning to minimise risks and to make choices that benefit humans. Eliezer Yudkowsky, who coined the term, argues that developing friendly AI should be a higher research priority: it may require a large investment and it must be completed before AI becomes an existential risk. Machines with intelligence have the potential to use their intelligence to make ethical decisions. The field of machine ethics provides machines with ethical principles and procedures for resolving ethical dilemmas. The field of machine ethics is also called computational morality, and was founded at an AAAI symposium in 2005. Geoffrey Hinton has suggested researchers explore instilling human-aligned values, such as compassion, into AI systems as a safeguard, speculating about the possibility of building "maternal instincts" into AI models, so “they really care about people”. Other approaches include Wendell Wallach's "artificial moral agents" and Stuart J. Russell's three principles for developing provably beneficial machines.
Sources: en.wikipedia.org
=== Other antifreezes === Propylene glycol methyl ether is used as an antifreeze in diesel engines. It is more volatile than glycol. Once used for automotive antifreeze, glycerol has the advantage of being non-toxic, withstands relatively high temperatures, and is noncorrosive. It is not however used widely. Glycerol was historically used as an antifreeze for automotive applications before being replaced by ethylene glycol. Volkswagen introduced G13 (TL 774-G) antifreezes containing glycerol in 2008, marketed as better for the environment due to its low toxicity and reduced CO2 emissions. However, since 2018, they have moved on to G12EVO (TL 774-L) which no longer contains glycerol. Glycerol is mandated for use as an antifreeze in many sprinkler systems.
=== Threonine === In plants and microorganisms, threonine is synthesized from aspartic acid via α-aspartyl-semialdehyde and homoserine. Homoserine undergoes O-phosphorylation; this phosphate ester undergoes hydrolysis concomitant with relocation of the OH group. Enzymes involved in a typical biosynthesis of threonine include aspartokinase, β-aspartate semialdehyde dehydrogenase, homoserine dehydrogenase, homoserine kinase, threonine synthase. The biosynthesis of threonine is regulated via allosteric regulation of its precursor, homoserine, by structurally altering the enzyme homoserine dehydrogenase. This reaction occurs at a key branch point in the pathway, with the substrate homoserine serving as the precursor for the biosynthesis of lysine, methionine, threonin and isoleucine. High levels of threonine result in low levels of homoserine synthesis. The synthesis of aspartate kinase (AK), which catalyzes the phosphorylation of aspartate and initiates its conversion into other amino acids, is feed-back inhibited by lysine, isoleucine, and threonine, which prevents the synthesis of the amino acids derived from aspartate. So, in addition to inhibiting the first enzyme of the aspartate families biosynthetic pathway, threonine also inhibits the activity of the first enzyme after the branch point, i.e. the enzyme that is specific for threonine's own synthesis.
=== Normal strain === For an isotropic material that obeys Hooke's law, a normal stress will cause a normal strain. Normal strains produce dilations. The normal strain in the x-direction of the rectangular element is defined by
Sources: en.wikipedia.org
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.
The tripeptide was first isolated from human plasma and has also been reported in saliva and urine. Plasma levels appear to decline with age in some small studies. Those observations rest on limited sample sizes.
It is not authorized as a systemic medicine in most countries. Cosmetic preparations list it as an ingredient rather than an active pharmaceutical substance. Legal status therefore differs by jurisdiction.
Identification usually combines reverse-phase high-performance liquid chromatography with mass spectrometry. The copper content can be measured separately by inductively coupled plasma mass spectrometry or atomic absorption spectroscopy. The combination helps distinguish the intact complex from free peptide or free copper.