Everything below concerns GHK-Cu. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-08-01. Where a claim depends on a specific study, the study is described rather than over-claimed.
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 molecular weight and charge of GHK-Cu depend on the pH and the number of coordinated ligands. At neutral pH, the peptide typically binds one copper ion, but ternary complexes with other biomolecules can form. Spectroscopic methods such as electron paramagnetic resonance and circular dichroism are used to study the coordination environment. Reports on the exact geometry vary because the complex is dynamic in solution. Researchers often use synthetic GHK-Cu rather than extracted material to control stoichiometry and purity.
GHK-Cu is a coordination complex formed from the tripeptide glycyl-L-histidyl-L-lysine and a copper(II) ion. The peptide binds copper through its histidine imidazole nitrogen, the terminal amino group, and the deprotonated amide nitrogen. This arrangement creates a square-planar or distorted geometry around the metal center, depending on pH and the presence of competing ligands. The complex occurs naturally in human plasma, saliva, and urine at low concentrations, and its sequence is conserved across many vertebrate species.
| 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 |
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.
Identity and purity are normally checked by reversed-phase high-performance liquid chromatography, often coupled to mass spectrometry. The peptide absorbs in the ultraviolet region, and the copper complex also shows a broad visible absorption band that can be followed spectroscopically. Copper content is measured separately, for example by inductively coupled plasma mass spectrometry or atomic absorption spectroscopy, because the peptide assay alone does not confirm how much metal is bound. Purity figures therefore need a stated basis: peptide peak area, copper content, or both.
Aqueous GHK-Cu solutions are less stable than the dry powder. Light, dissolved oxygen and elevated temperature all accelerate loss of the intact complex, and the main observable changes are fading of the blue colour and the appearance of peptide fragments. Acidic conditions protonate the histidine imidazole and weaken copper binding, while strongly alkaline conditions promote hydrolysis of the peptide backbone. Because several degradation routes operate at once, a single shelf-life figure does not describe all storage conditions.
Identity and purity are established with a combination of chromatographic and spectroscopic techniques. Reversed-phase high-performance liquid chromatography separates the intact complex from peptide fragments and free copper, and the elution profile yields a purity estimate. Mass spectrometry gives the mass of the intact species and exposes degradation products. Ultraviolet-visible spectroscopy displays a broad absorption band in the visible region that is characteristic of the copper center. Nuclear magnetic resonance is less informative here, because the paramagnetic metal broadens signals and complicates spectral interpretation.
Copper content is measured separately, since a peptide assay alone does not report the metal-to-peptide ratio. Elemental techniques such as inductively coupled plasma optical emission spectroscopy quantify copper after acid digestion of the sample. The result is compared with the theoretical value for a one-to-one complex, and a shortfall indicates free peptide or partial dissociation. Suppliers differ in how they state purity, as some quote peptide content and others quote the whole complex. A defined stoichiometry therefore requires both a peptide assay and a copper assay.
A 2013 review found the data too weak to support use of Chinese herbal medicine (CHM) for benign prostatic hyperplasia. A 2013 review found the research on the benefit and safety of CHM for idiopathic sudden sensorineural hearing loss is of poor quality and cannot be relied upon to support their use. A 2013 Cochrane review found inconclusive evidence that CHM reduces the severity of eczema. The traditional medicine ginger, which has shown anti-inflammatory properties in laboratory experiments, has been used to treat rheumatism, headache and digestive and respiratory issues, though there is no firm evidence supporting these uses. A 2012 Cochrane review found no difference in mortality rate among 640 SARS patients when Chinese herbs were used alongside Western medicine versus Western medicine exclusively, although they concluded some herbs may have improved symptoms and decreased corticosteroid doses. A 2012 Cochrane review found insufficient evidence to support the use of TCM for people with adhesive small bowel obstruction. A 2011 review found low quality evidence that suggests CHM improves the symptoms of Sjögren's syndrome. A 2011 Cochrane review found inconclusive evidence to support the use of TCM herbal medicines for treatment of hypercholesterolemia. A 2011 Cochrane review did not find improvement in fasting C-peptide when compared to insulin treatment for latent autoimmune diabetes in adults after 3 months. It is important to highlight that the studies available to be included in this review presented considerable flaws in quality and design.
After John's death, Constantine VII's grandsons Basil II and Constantine VIII ruled jointly for half a century, although the latter exercised little real power. Their early reign was occupied by conflicts against two prominent generals, Bardas Skleros and Bardas Phokas, which ended in 989 after Phokas's death and Skleros's submission, and by a power struggle against the eunuch Basileios, who was dismissed in 985. Basil, who never married or had children, subsequently refused to delegate much authority: he took personal command of the army, sidelined established military families, and promoted officers loyal to him. His reign witnessed the decades-long campaign against Bulgaria, in which the Battle of Kleidion in 1014 proved decisive before the final Byzantine conquest in 1018. Diplomatic efforts, critical for this success, also contributed to the annexation of Caucasian territories in the 1020s and coexistence with the new Fatimid Caliphate. When he died in 1025, Basil's empire stretched from the Danube and southern Italy in the west to the Euphrates in the east; his rapid expansion was not matched by comparable administrative reforms.
Norbornenes were selected as dipolarophiles due to their balance between strain-promoted reactivity and stability. The drawbacks of this reaction include the cross-reactivity of the nitrile oxide due to strong electrophilicity and slow reaction kinetics.
=== Plasma or whole blood === In this article, all values (except the ones listed below) denote blood plasma concentration, which is approximately 60–100% larger than the actual blood concentration if the amount inside red blood cells (RBCs) is negligible. The precise factor depends on hematocrit as well as amount inside RBCs. Exceptions are mainly those values that denote total blood concentration, and in this article they are:
Yeast is the microorganism that is responsible for fermentation in beer. Yeast metabolises the sugars extracted from grains, which produces alcohol and carbon dioxide, and thereby turns wort into beer. In addition to fermenting the beer, yeast influences the character and flavour. The dominant types of yeast used to make beer are Saccharomyces cerevisiae, known as ale yeast, and Saccharomyces pastorianus, known as lager yeast; Brettanomyces ferments lambics, and Torulaspora delbrueckii ferments Bavarian weissbier. Before the role of yeast in fermentation was understood, fermentation involved wild or airborne yeasts, and a few styles such as lambics still use this method today. Emil Christian Hansen, a Danish biochemist employed by the Carlsberg Laboratory, developed pure yeast cultures which were introduced into the Carlsberg brewery in 1883, and pure yeast strains are now the main fermenting source used worldwide.
Sources: en.wikipedia.org
=== Reston virus: monkeys with ebola virus brought to U.S. === In December 1989, several crab-eating macaques with the Zaire ebolavirus were imported from Mindanao in the Philippines to the company's facility in Reston, Virginia. The strain of the virus became known as the Reston virus. It was the first ebola virus that emerged outside of Africa and was also the first known natural infection of ebola virus in nonhuman primates. The facility was abandoned and torn down and the variant turned out to be non-lethal to humans. The incident was an inspiration for The Hot Zone, a book by Richard Preston published in 1994. In March 1996, two macaques that had been shipped to the company's facility in Alice, Texas, tested positive for the Ebola virus from a group of 100 obtained from the same supplier. The virus strain was the same non-lethal Reston virus as in the earlier incident.
Monitoring members' progress in implementing anti–money laundering measures, Reviewing and reporting on laundering trends, techniques, and countermeasures, and Promoting the adoption and implementation of FATF anti–money laundering standards globally. The FATF currently comprises 34 member jurisdictions and 2 regional organisations, representing most major financial centres in all parts of the globe. The United Nations Office on Drugs and Crime maintains the International Money Laundering Information Network, a website that provides information and software for anti–money laundering data collection and analysis. The World Bank has a website that provides policy advice and best practices to governments and the private sector on anti–money laundering issues. The Basel AML Index is an independent annual ranking that assesses the risk of money laundering and terrorist financing around the world.
Polysulfated glycosaminoglycan (PSGAG; sold under the brand name Adequan) is an injectable drug for dogs and horses that is used to alleviate the limpness, pain, and lowered range of motion caused by arthritis. It is made of repeat disaccharide units (comprising hexosamine and hexuronic acid), and is similar to glycosaminoglycans already present in the cartilage; PSGAG thus easily integrates itself there. In vitro studies have shown it to inhibit the enzymes that degrade cartilage and bone, as well as suppress inflammation and stimulate the synthesis of replacement cartilage. While it can cause an increased risk of bleeding, it is relatively safe and has a high LD50. PSGAG is one of the most widely prescribed joint treatments for horses. While it is widely used, some studies still show conflicting results in terms of efficacy, causing some to claim that PSGAG is not solely responsible for the significant mitigation of arthritis seen in success cases.
== History == Source distantly originates from the GoldSrc engine, itself a heavily modified version of John Carmack's Quake engine with some code from the Quake II engine. Carmack commented on his blog in 2004 that "there are still bits of early Quake code in Half-Life 2". Valve employee Erik Johnson explained the engine's nomenclature on the Valve Developer Community:
Sources: en.wikipedia.org
Furthermore, the Japanese defensive plans had been directly obtained by the Allies from the wreckage of a plane carrying the commander-in-chief of the Imperial Japanese Navy's Combined Fleet, Admiral Mineichi Koga, in March 1944. During the course of the battle, American submarines torpedoed and sank two of the largest Japanese fleet carriers taking part in the battle. The American carriers launched a protracted strike, sinking one light carrier and damaging other ships, but most of the American aircraft returning to their carriers ran low on fuel as night fell. Eighty American planes were lost. Although at the time the battle appeared to be a missed opportunity to destroy the Japanese fleet, the Imperial Japanese Navy had lost the bulk of its carrier air strength and would never recover. This battle, along with the Battle of Leyte Gulf four months later, marked the end of Japanese aircraft carrier operations. The few surviving carriers remained mostly in port thereafter.
A colorant is any substance that changes the spectral transmittance or reflectance of a material. Synthetic colorants are those created in a laboratory or industrial setting. The production and improvement of colorants was a driver of the early synthetic chemical industry, in fact many of today's largest chemical producers started as dye-works in the late 19th or early 20th centuries, including Bayer AG (1863). "Synthetics" achieve intensity, color fastness, and reproducibility that natural materials can rarely match. Market viable large scale production of dyes occurred nearly simultaneously in the early major producing countries United Kingdom of Great Britain and Ireland (1857), Second French Empire (1858), German Confederation (1858), and Switzerland (1859), and expansion of associated chemical industries followed. The mid-19th century through World War II saw an incredible expansion of the variety and scale of manufacture of synthetic colorants. Synthetic colorants quickly became ubiquitous in everyday life, from clothing to food. This stems from the invention of industrial research and development laboratories in the 1870s, and the new awareness of empirical chemical formulas as targets for synthesis by academic chemists. The dye industry became one of the first instances where directed scientific research lead to new products, and the first where this occurred regularly.
=== Receptor activation === The initial triggering follows the mechanism common for all NTR receptor family members. Once the TCR binds a specific pMHC, the tyrosine residues of the immunoreceptor tyrosine-based activation motifs (ITAMs) in its CD3 adaptor proteins are phosphorylated. The residues serve as docking sites for downstream signaling molecules, which can propagate the signal. Phosphorylation of ITAMs is mediated by the Src kinase Lck. Lck is anchored to the plasma membrane by associating with the co-receptor CD4 or CD8, depending on the T-cell subtype. CD4 is expressed on helper T cells and regulatory T cells, and is specific for MHC class II. CD8, on the other hand, specific for MHC class I, is expressed on cytotoxic T cells. Binding of the co-receptor to the MHC brings Lck in close proximity to the CD3 ITAMs. It has been shown that 40% of Lck is active even before the TCR binds pMHC and therefore has the ability to constantly phosphorylate the TCR. Tonic TCR signaling is avoided by the presence of phosphatase CD45 that removes phosphorylation from tyrosine residues and inhibits signal initiation. Upon binding the balance of kinase activity to phosphatase activity is perturbed, leading to a surplus of phosphorylation and initiation of the signal. How such perturbation is accomplished by TCR binding is still debated. Mechanisms involving conformational change of TCR, TCR aggregation and kinetic segregation have been suggested. Tyrosine kinase Fyn might be involved in ITAM phosphorylation but is not essential for TCR signaling.
== External links == Association des medecins rhumatologues du Quebec American College of Rheumatology European League Against Rheumatism Consortium of Rheumatology Researchers of North America, Inc. British Society for Rheumatology Canadian Rheumatology Association Association of Rheumatology Health Professionals (archived 3 March 2009) German Society for Rheumatology
== Development and Organization == During cartilage development mesenchymal stem cells differentiate into chondrocytes, secreting various extracellular proteins, giving rise to the unique matrix zones. The territorial matrix develops as chondrocytes release collagen and proteoglycans, among other supporting organic molecules. These extracellular proteins form chondrons, a functional unit consisting of chondrocytes, the pericellular matrix, and the territorial matrix in order extending outward. Differences in the concentrations of molecules and fibril organization between the regions lead to clear patterns typical of mature cartilage. The articular cartilage shows variation across different zones in the extracellular matrix. Superficially, the collagen fibrils run parallel to the surface, resisting shear forces. In the middle zone, the fibrils are arranged randomly, allowing for optimal compressive absorption. The deep zone contains perpendicular fibrils, anchoring cartilage to the bone and transferring load. These gradients allow the territorial matrix to distribute its mechanical properties across zones.
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.
GHK-Cu is a complex of the tripeptide glycyl-L-histidyl-L-lysine with copper(II). The peptide coordinates the metal through its histidine imidazole, terminal amino group, and amide nitrogen. It is studied in biochemistry and dermatological research.