Everything below concerns Copper(II). We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2025-10-10. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
| Property | Value | Notes |
|---|---|---|
| INCI name | Copper tripeptide-1 | Standard designation on cosmetic ingredient labels |
| Peptide sequence | Gly-His-Lys | Three-residue ligand; binding occurs at the histidine side chain |
| Metal-to-peptide ratio | 1 to 1 | One copper(II) ion per peptide unit |
| Appearance | Blue to violet powder | Colour arises from copper-to-peptide electronic transitions |
| Water solubility | Freely soluble | Commonly formulated in aqueous or water-alcohol systems |
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 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.
Bryant Park contains a Beaux-Arts granite restroom structure on the northern border, along 42nd Street. There are two facilities, one for men and women, both of which are 315 square feet (29.3 m2). These were built in 1911 along with the NYPL Main Branch, but due to the park's landmark status, they cannot be expanded. The exterior of each building contains a frieze with garland motifs. After being closed in the mid-1960s, they were restored by Kupiec & Koutsomitis and reopened in 1992. The restrooms have been described as being among the city's best. A subsequent renovation in 2006 solidified their status as, in the words of then-New York City Parks Commissioner Adrian Benepe, "the gold standard for park comfort stations." The restrooms were renovated again in 2017. Following the 2017 renovation, the restrooms contained rotating artworks selected from a collection of 225 works, as well as fresh flowers, classical music, attendants, and automatic toilets and faucets.
=== Myxedema coma === Myxedema coma or severe decompensated hypothyroidism usually requires admission to the intensive care unit, close observation and treatment of abnormalities in breathing, temperature control, blood pressure, and sodium levels. Mechanical ventilation may be required, as well as fluid replacement, vasopressor agents, careful rewarming, and corticosteroids (for possible adrenal insufficiency which can occur together with hypothyroidism). Careful correction of low sodium levels may be achieved with hypertonic saline solutions or vasopressin receptor antagonists. For rapid treatment of hypothyroidism, levothyroxine or liothyronine may be administered intravenously, particularly if the level of consciousness is too low to be able to safely swallow medication. While administration through a nasogastric tube is possible, this may be unsafe and is discouraged.
One rack unit (U) is 1.75 inches (44.45 mm) and is used to measure rack-mountable audiovisual, computing and industrial equipment. Rack units are typically denoted without a space between the number of units and the 'U'. Thus, a 4U server enclosure (case) is nominally seven inches (177.8 mm) high, or more precisely, built to occupy a vertical space seven inches high, with sufficient clearance to allow movement of adjacent hardware.
As a salt, its dominant use is as an emulsifier for the emulsion polymerization of fluoropolymers such as PTFE, polyvinylidene fluoride, and fluoroelastomers. For this use, 3M subsidiary Dyneon has a replacement emulsifer despite DuPont stating PFOA is an "essential processing aid". In the past PFOA was used in the production of Gore-Tex as it is PTFE-based. In PTFE processing, PFOA is in aqueous solution and forms micelles that contain tetrafluoroethylene and the growing polymer. PFOA can be used to stabilize fluoropolymer and fluoroelastomer suspensions before further industrial processing and in ion-pair reversed-phase liquid chromatography it can act as an extraction agent. PFOA also finds uses in electronic products and as an industrial fluorosurfactant. In a 2009 EPA study of 116 products, purchased between March 2007 and May 2008 and found to contain at least 0.01% fluorine by weight, the concentrations of PFOA were determined. Concentrations shown below range from not detected, or ND, (with the detection limit in parentheses) to 6750 with concentrations in nanograms of PFOA per gram of sample (parts per billion) unless stated otherwise.
Sources: en.wikipedia.org
=== Food and Drug Administration (FDA) === In vitro diagnostic (IVD) products use the same categorization as medical devices (Class I, II, and III) to assure safety and effectiveness. Regulatory controls and premarket approval process are determined by this classification, with Class I being the lowest risk (least regulated) and Class III being the highest risk (most regulated). Under the CLIA, it is the role of the FDA to assess the complexity of the in vitro laboratory diagnostic tests. Tests are only scored after the FDA has cleared or approved a premarketing request, or upon request. Manufacturers can apply for CLIA waivers during this premarket approval/clearance process. Tests that are already cleared or approved for home use or are waived by 42 CRF 293.15(c), are classified as waived. Otherwise, the tests are either classified as moderate or high complexity based on seven categorization criteria listed in 42 CFR 493.17. If the test is classified as moderate, the manufacturer may request the test be waived through the CLIA Waiver by Application. The application must show that the test meets the criteria in 42 U.S.C. § 263a(d)(3), that the test is simple and will not cause harm to the patient if performed incorrectly. These test classifications determine the certifications needed for laboratories to perform said tests. Waived tests require the least regulation, while moderate to high complexity tests require higher regulation and standards within the laboratory.
Trimethylsilyl (TMS) — Potassium fluoride, acetic acid or potassium carbonate in methanol Triethylsilyl (TES) — 10–100× stabler than a TMS group. Cleaved with trifluoroacetic acid in water/tetrahydrofuran, acetic acid in water/tetrahydrofuran, or hydrogen fluoride in water or pyridine tert-Butyldimethylsilyl (TBDMS or TBS) — Cleaved with acetic acid in tetrahydrofuran/water, Pyridinium tosylate in methanol, trifluoroacetic acid in water, hydrofluoric acid in acetonitrile, pyridinium fluoride in tetrahydrofuran, tetrabutylammonium fluoride in THF. Commonly protects 2'-hydroxy function in oligonucleotide synthesis. Triisopropylsilyl (TIPS) — Similar conditions to TBS but longer reaction times. tert‑Butyldiphenylsilyl (TBDPS) — Similar conditions to TBS but even longer reaction times (100–250× slower than TBS and 5–10× slower than TIPS) Benzyl ethers:
== History == Opipramol was developed by Geigy. It first appeared in the literature in 1952 and was patented in 1961. The drug was first introduced for use in medicine in 1961. Opipramol was one of the first TCAs to be introduced, with imipramine marketed in the 1950s and amitriptyline marketed in 1961.
== Medical uses == Oritavancin is considered a long-lasting antibiotic due to its extended half-life (up to 16 d), high protein binding capacity, and ability to penetrate tissues effectively. It binds strongly to plasma proteins (around 85%), resulting in prolonged release into surrounding tissues. Furthermore, oritavancin exhibits excellent tissue penetration and distribution throughout various sites, including skin structures, synovial fluid (found in joints), bone tissue, and macrophages. Less frequent dosing requirements still keep efficacy against gram-positive infections, which is convenient for prolonged treatment courses such as osteoarticular infections and endocarditis, making it an option for outpatient antibiotic therapy in difficult-to-treat populations where adherence may be challenging and those with limited access to healthcare facilities.
Biological value (BV) is a measure of the proportion of absorbed protein from a food which becomes incorporated into the proteins of the organism's body. It captures how readily the digested protein can be used in protein synthesis in the cells of the organism. Proteins are the major source of nitrogen in food. BV assumes protein is the only source of nitrogen and measures the amount of nitrogen ingested in relation to the amount which is subsequently excreted. The remainder must have been incorporated into the proteins of the organisms body. A ratio of nitrogen incorporated into the body over nitrogen absorbed gives a measure of protein "usability" – the BV. Unlike some measures of protein usability, biological value does not take into account how readily the protein can be digested and absorbed (largely by the small intestine). This is reflected in the experimental methods used to determine BV. BV uses two similar scales:
Sources: en.wikipedia.org
=== Background === In the mid-1960s, the United States and Western Europe planned airliners seating twice the then-maximum of some 200 passengers. They were known as airbuses at the time. The Soviet leadership wanted to match them with an aerobus (Russian: аэробус). Alongside the propaganda motive, the USSR genuinely needed an aerobus. Aeroflot expected over 100 million passengers a year within a decade (the 100th million annual passenger was indeed carried on 29 December 1976.) First to respond was OKB-153, the bureau led by Oleg Antonov. It proposed a 724-seat version of the An-22 airlifter. The project was promoted until 1969, ultimately with a 605-passenger interior (383 on the upper deck and 223 on the lower). It did not go ahead due to fears that it would be old-fashioned and because the Kiev-based bureau was close to the deposed Nikita Khrushchev.
== Cancer == DPEP1 has been found to be highly expressed in colon tumor cells compared to normal colon cells—one study even found a ≥2 fold over-expression of DPEP1. Increased levels of DPEP1 have also been detected in colorectal cancer patients, suggesting that DPEP1 is a viable marker for disseminated colon tumor cells.
== Secular Frequency and Pseudopotential Well Depth == Secular frequency is the fundamental frequency component of the ion motion in the quadrupole field driven by a periodical signal, and it is usually chosen for resonance excitation of ion motion to achieve ion ejection, and/or ion energy activation which may lead to the collision induced dissociation. The secular frequency is conventionally written as:
Half-Life: Alyx received "universal acclaim", according to the review aggregator website Metacritic. According to the review aggregator OpenCritic, it was recommended by 97% of critics. By April 2020, it was one of the 20 highest-rated PC games on Metacritic. VG247, TechRadar and Video Games Chronicle described it as VR's "killer app". The announcement trailer was watched more than 10 million times within the first 24 hours of its release. Though most fans expressed excitement, some were disappointed that Alyx was only available in VR, a small but growing market in 2019. Vic Hood of TechRadar expressed enthusiasm but wrote that "we forever live in hope" for Half-Life 3. Kevin Webb of Business Insider wrote that Alyx could "spark fresh interest in an industry [VR] that has struggled to win over hardcore gamers". Andrew King of USGamer suggested that Alyx would test whether the modding community would embrace VR, a difficult area to work in. In IGN, Dan Stapleton wrote that Alyx was one of the best shooter games and the best VR shooter by far. He felt that Valve "set a new bar for VR in interactivity, detail, and level design ... It feels like a game from the future, and one that the rest of VR gaming will likely take a good long while to match, much less surpass." In Polygon, Ben Kuchera wrote of how Alyx transformed FPS systems. For example, he felt that reloading guns, traditionally performed with a button press, was more fun in VR. He wrote: "The magic lies in being inside the world, being able to touch it, and interact with it, directly.
=== Salicylic acid === Willow bark has been used for centuries as a painkiller. The active ingredient in willow bark that provides these effects is the hormone salicylic acid (SA). In 1899, the pharmaceutical company Bayer began marketing a derivative of SA as the drug aspirin. In addition to its use as a painkiller, SA is also used in topical treatments of several skin conditions, including acne, warts and psoriasis. Another derivative of SA, sodium salicylate has been found to suppress proliferation of lymphoblastic leukemia, prostate, breast, and melanoma human cancer cells.
Sources: en.wikipedia.org
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.
The free peptide was reported in 1973 by Loren Pickart, who isolated it from human plasma. Its copper-binding behaviour was characterised over the following years. The metal-bound form has been the subject of most later research.
Yes. Copper tripeptide-1 is the name used in cosmetic ingredient labelling, while GHK-Cu is the shorthand found in the scientific literature. Both refer to the same peptide-copper complex, and the two terms are interchangeable in most technical documents.
It is the copper(II) complex of the tripeptide glycyl-L-histidyl-lysine, a sequence of three amino acids. The copper ion is held by the histidine imidazole, the terminal amino group, and an amide nitrogen. The bound form is distinct from the free peptide in charge, color, and stability.