This is a working overview of copper(II) complex, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-04-02 and is reviewed periodically as new material appears.
Stability of the complex in solution depends on pH, temperature, and the presence of competing ligands. It is generally described as more resistant to breakdown than the metal-free chain, since coordination reduces susceptibility to enzymatic attack. Oxidation and hydrolysis can nevertheless proceed over time in aqueous media. Storage guidance in laboratory settings commonly involves refrigeration, protection from light, and avoidance of strongly alkaline conditions. Published data on long-term behaviour vary considerably and depend on the specific matrix.
Handling practices for the solid material emphasise low temperature and dryness. The lyophilised or powdered form is typically kept at refrigerator or freezer temperatures together with a desiccant. Working solutions are often prepared fresh, because repeated freeze-thaw cycles and extended storage may alter the complex. Glass or inert plastic containers are preferred over materials that could leach metal ions into the preparation. Such practices follow general peptide conventions rather than substance-specific regulations.
GHK-Cu is a coordination complex formed between the tripeptide glycyl-L-histidyl-lysine and a copper(II) ion. The peptide sequence is conventionally written as Gly-His-Lys, abbreviated GHK. Copper binds through the imidazole nitrogen of histidine, the alpha-amino group, and a deprotonated amide nitrogen, producing a square-planar geometry. The complex carries a net positive charge near physiological pH and is intensely blue in aqueous solution. The metal-free peptide is often written simply as GHK, while the copper-bound form is written GHK-Cu.
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.
| Property | Value | Notes |
|---|---|---|
| Appearance | Blue crystalline solid | Colour arises from copper(II) d-d transitions |
| Water solubility | Readily soluble | Extent varies with pH and counterion |
| Typical storage | Minus 20 degrees Celsius, desiccated | Protect from light and moisture |
| Purity method | Reverse-phase HPLC, UV detection | Wavelength typically 214 or 220 nanometres |
| Identity method | Mass spectrometry | Confirms peptide mass and copper content |
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.
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.
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.
=== Costs === At between US$6,000 and $10,000 for a typical treatment, BMPs can be costly compared with other techniques such as bone grafting. However, this cost is often far less than the costs required with orthopaedic revision in multiple surgeries. While there is little debate that rhBMPs are successful clinically, there is controversy about their use. It is common for orthopedic surgeons to be paid for their contribution to the development of a new product, but some of the surgeons responsible for the original Medtronic-supported studies on the efficacy of rhBMP-2 have been accused of bias and conflict of interest. For example, one surgeon, a lead author on four of these research papers, did not disclose any financial ties while with the company on three of the papers; he was paid over $4 million by Medtronic. In another study, the lead author did not disclose any financial ties to Medtronic; he was paid at least $11 million by the company. In a series of 12 publications, the median financial ties of the authors to Medtronic were $12–16 million. In those studies that had more than 20 and 100 patients, one or more authors had financial ties of $1 million and $10 million, respectively. Early clinical trials using rhBMP-2 underreported adverse events associated with treatment. In the 13 original industry-sponsored publications related to safety, there were zero adverse events in 780 patients. It has since been revealed that potential complications can arise from the use including implant displacement, subsidence, infection, urogenital events, and retrograde ejaculation.
=== Mantis shrimp === The clubbing appendages of the Odontodactylus scyllarus (peacock mantis shrimp) are made of an extremely dense form of the mineral which has a higher specific strength; this has led to its investigation for potential synthesis and engineering use. Their dactyl appendages have excellent impact resistance due to the impact region being composed of mainly crystalline hydroxyapatite, which offers significant hardness. A periodic layer underneath the impact layer composed of hydroxyapatite with lower calcium and phosphorus content (thus resulting in a much lower modulus) inhibits crack growth by forcing new cracks to change directions. This periodic layer also reduces the energy transferred across both layers due to the large difference in modulus, even reflecting some of the incident energy.
13 September Space - the Final Junkyard, about space debris; Nick Johnson of NASA; Paul Maley of United Space Alliance, and JSC Astronomical Society; Mark Mulrooney of the NASA Orbital Debris Observatory, and its liquid-mirror telescope; Scott J. Horowitz; Pam McCraw of Mission Operations Directorate at the Johnson Space Center in Texas; the Institute for Advanced Technology at the University of Texas at Austin; Richard Crowther of the Defence Evaluation and Research Agency; Don Kessler of NASA JSC; the French reconnaissance Cerise (satellite), which was damaged on 24 July 1996 by debris from Ariane; Darren McKnight and Kosmos 1275, launched on 4 June 1981, and was damaged on 24 July 1981; on 24 January 1978, the nuclear-powered Kosmos 954, a RORSAT, crashed into Canada; The Aerospace Corporation; the Russian Mars 96 was launched on 16 November 1996, to hopefully reach Mars on 12 September 1997, but re-entered the atmosphere east of Iquique in north Chile on 17 November 1997, carrying 270g of plutonium; as part of NASA's Systems for Nuclear Auxiliary Power, the satellite Transit 5BN-3 with a SNAP-9A nuclear power source, launched from Vandenberg Air Force Base (since May 2021, Vandenberg Space Force Base) in California, and never reached orbit on 21 April 1964, dispersing 1 kg of plutonium-238; the Iridium satellite constellation of 66 telecommunication satellites and the proposed Teledesic scheme; a damaged satellite could cause the catastrophic Kessler syndrome; John Muratore and the NASA X-38.
Sources: en.wikipedia.org
== Use == Although AH-7921 was extensively studied in vitro and in animals, though not in humans, by the developing company, it was never sold commercially for medical use. In 2013, AH-7921 was discovered to have been used as an active ingredient in "synthetic cannabis" products in Japan. In October 2015, two horses (Bossmon and Literata) trained by owner-trainer Roy Sedlacek tested positive for AH-7921 at Belmont Park racetrack. Norway and Iceland use this substance as an analytical reference standard in which it can be ordered online from chemical suppliers; however, labels are required to state that it is not for human consumption thus conforming to the law. Within ten months from 2013 to 2014, there had been serious fatalities reported from this drug from four different countries. The first fatality was a 19-year-old male who had a 3.9 mg/L AH-7921 concentration of heart blood leading medical examiners to confirm the death was an opioid intoxication. In another case, a 22-year-old woman was found dead with a femoral blood to AH-7921 concentration of 450 μg/L. A 2018 review of published case reports found a total of 14 cases, of which 13 resulted in death. The oral route of administration was reported in two cases, and most cases reported use of concomitant pharmaceutical agents. Postmortem autopsies found that pulmonary edema was the most common finding, with nine of the cases having heavier lungs. Overall, fatalities occurred with low and high concentrations of AH-7921 in femoral blood.
== Management == MASLD warrants treatment regardless of whether the affected person is overweight. MASLD is a preventable cause of death. Guidelines are available from the American Association for the Study of Liver Diseases (AASLD), American Association of Clinical Endocrinologists (AACE) National Institute for Health and Care Excellence (NICE), the European Association for the Study of the Liver (EASL), and the Asia-Pacific Working Party on MASFLD.
Trazodone is a mixed agonist and antagonist of various serotonin receptors, antagonist of adrenergic receptors, weak histamine H1 receptor antagonist, and weak serotonin reuptake inhibitor. More specifically, it is an antagonist of 5-HT2A and 5-HT2B receptors, a partial agonist of the 5-HT1A receptor, and an antagonist of the α1- and α2-adrenergic receptors. It is also a ligand of the 5-HT2C receptor with lower affinity than for the 5-HT2A receptor. However, it is unknown whether trazodone acts as a full agonist, partial agonist, or antagonist of the 5-HT2C receptor. Trazodone is a 5-HT1A receptor partial agonist similarly to buspirone and tandospirone but with comparatively greater intrinsic activity. A range of weak affinities (Ki) have been reported for trazodone at the human histamine H1 receptor, including 220 nM, 350 nM, 500 nM, and 1,100 nM. Trazodone has a minor active metabolite known as meta-chlorophenylpiperazine (mCPP), and this metabolite may contribute to some degree to the pharmacological properties of trazodone. In contrast to trazodone, mCPP is an agonist of various serotonin receptors. It has relatively low affinity for α1-adrenergic receptors unlike trazodone, but does have high affinity for α2-adrenergic receptors and weak affinity for the H1 receptor. In addition to direct interactions with serotonin receptors, mCPP is a serotonin releasing agent similarly to agents like fenfluramine and MDMA.
On 25 November, while sending a congratulatory message to President Maduro, CCP General Secretary Xi Jinping stated that China supports Venezuela in "safeguarding its sovereignty and national security, the dignity of the nation, and social stability" and "resolutely opposes the meddling of external forces in Venezuela's internal affairs under any pretext". Iran said that US military action in the Caribbean was provocative, destabilizing, and a threat to regional and global peace. Several Iranian officials, including Foreign Ministry spokesman Esmaeil Baghaei, stated that US military actions such as attacks on Venezuelan ships violated the United Nations Charter and international law. Iran has also turned to the UN Security Council and the UN Secretary-General to act quickly.
Sources: en.wikipedia.org
=== Legal status === Risperidone was approved by the United States Food and Drug Administration (FDA) in 1993 for the treatment of schizophrenia. In 2003, the FDA approved risperidone for the short-term treatment of the mixed and manic states associated with bipolar disorder. In 2006, the FDA approved risperidone for the treatment of irritability in autistic children and adolescents. The FDA's decision was based in part on a study of autistic people with severe and enduring problems of violent meltdowns, aggression, and self-injury; risperidone is not recommended for autistic people with mild aggression and explosive behavior without an enduring pattern. On 22 August 2007, risperidone was approved as the only drug agent available for the treatment of schizophrenia in youths, ages 13–17; it was also approved that same day for the treatment of bipolar disorder in youths, ages 10–17, joining lithium. In December 2021, the Committee for Medicinal Products for Human Use of the European Medicines Agency recommended market authorization for Okedi, a long-acting depot injection of risperidone. Okedi was approved for the treatment of schizophrenia in adults for whom the tolerability and effectiveness of risperidone had already been established using an oral formulation. Long-acting depot injectable risperidone was approved for medical use in the European Union in February 2022.
=== Legal status === Suvorexant is a schedule IV controlled substance under the Controlled Substances Act in the United States. It is not a controlled drug in Australia, instead being classed as a prescription-only medicine (Schedule 4 (S4)) in this country.
Official Mister Donut Japan website (in Japanese) Official Mister Donut Taiwan website (in Chinese) Official Mister Donut Philippines website (in English) Official Mister Donut Thailand website Archived January 2, 2019, at the Wayback Machine (in Thai) Official Mister Donut Singapore website (in English) Official Mister Donut El Salvador website (in Spanish) Mister Donut website of Elie G. Saheb and Associates
Sources: en.wikipedia.org
Reverse-phase high-performance liquid chromatography with ultraviolet detection is the most common approach. Purity is expressed as a share of total peak area at a specified wavelength. Mass spectrometry is then used to confirm molecular identity.
Solid material is often held at refrigerator or freezer temperatures, typically between minus 20 and 4 degrees Celsius. Desiccation limits moisture uptake. Solution stability is generally shorter and varies with pH and buffer composition.
Electron paramagnetic resonance is suited to copper(II) because of its unpaired electron. UV-visible spectroscopy reveals ligand-to-metal charge transfer bands. Both methods report on coordination rather than on peptide purity.
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.