This is a working overview of metal chelation, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-03-29. Anything still debated is marked as such rather than presented as settled.
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.
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.
Quality control for GHK-Cu relies on documentation and independent testing rather than a single accepted standard. A certificate of analysis may report peptide purity, copper content, residual solvents, water content, and microbial limits, but the underlying methods and acceptance criteria vary by supplier. Verification can include mass confirmation, amino acid analysis, and comparison with a reference standard when one is available. Open questions include how different copper-binding modes or peptide isomers affect measured activity and whether conventional purity assays capture those differences. Buyers of research-grade material typically need to request raw data rather than rely solely on a summary certificate.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C14H22CuN6O4 as the complex | Free peptide is C14H24N6O4 |
| Molecular weight | About 402 g/mol | Free peptide is about 340 g/mol |
| Appearance | Blue solid or blue solution | Color from copper d-d transitions |
| Solubility class | Water-soluble; poor in nonpolar solvents | Ionic character favors aqueous media |
| Common synonyms | Copper tripeptide-1; glycyl-L-histidyl-L-lysine copper | INCI listing uses copper tripeptide-1 |
GHK-Cu is the copper(II) complex of the tripeptide glycyl-L-histidyl-L-lysine, a short sequence of three amino acids. The peptide was first isolated from human plasma in 1973 during research on factors that influence tissue repair in liver. Its ability to bind copper ions became a central point of interest because the metal changes the peptide's chemistry and its behaviour in laboratory systems. Today the compound appears in cosmetic formulations, cell-culture studies, and biochemistry literature under several names.
The peptide sequence places a histidine in the middle, and this residue dominates metal binding. Copper(II) coordinates through the imidazole nitrogen of histidine and the terminal amino group, forming a stable chelate ring system. Loss of the copper ion leaves the free tripeptide, which has different solubility and reactivity. This structural detail matters because assays that measure only the peptide backbone can miss whether copper is still bound to it.
Solid GHK-Cu is usually supplied as a lyophilized powder and is kept cold and dry. Moisture, light, and repeated temperature cycling shorten its useful life in the laboratory. In aqueous solution the complex undergoes slow hydrolysis of the peptide backbone and gradual loss of coordinated copper. Buffers containing strong chelators, such as EDTA, compete for the metal and strip it from the peptide. Working solutions are therefore prepared shortly before use, and leftover liquid is not returned to the stock container.
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 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.
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.
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.
Discovery of GHK is generally attributed to work in the 1970s that isolated a plasma factor influencing liver cell behavior. Subsequent studies identified the copper-binding tripeptide and its ability to chelate copper with high affinity. Early reports linked the complex to wound healing and tissue remodeling in animal models. The free peptide and the copper-bound form have different properties, so the two are distinguished in the literature. Whether endogenous GHK-Cu serves a single primary physiological role remains an open question.
Technetium, with atomic number Z = 43, is the lowest-numbered element in the periodic table for which all isotopes are radioactive. The second-lightest exclusively radioactive element, promethium, has atomic number 61. Atomic nuclei with an odd number of protons are less stable than those with even numbers, even when the total number of nucleons (protons + neutrons) is even, and odd numbered elements have fewer stable isotopes. The most stable radioactive isotopes are technetium-97 with a half-life of 4.21±0.16 million years and technetium-98 with 4.2±0.3 million years; current measurements of their half-lives give overlapping confidence intervals corresponding to one standard deviation and therefore do not allow a definite assignment of technetium's most stable isotope. The next most stable isotope is technetium-99, which has a half-life of 211,100 years. Thirty-four other radioisotopes have been characterized with mass numbers ranging from 86 to 122. Most of these have half-lives that are less than an hour, the exceptions being technetium-93 (2.75 hours), technetium-94 (4.88 hours), technetium-95 (19.26 hours), and technetium-96 (4.28 days). The primary decay mode for isotopes lighter than technetium-98 (98Tc) is electron capture, producing molybdenum (Z = 42). For technetium-98 and heavier isotopes, the primary mode is beta emission (the emission of an electron or positron), producing ruthenium (Z = 44), with the exception that technetium-98 and technetium-100 can decay both by beta emission and electron capture.
== Neurodegeneration == Inhibition of Hsp90 leads to Hsp70 and Hsp40 upregulation, which can channel misfolded protein for proteasome degradation, which can potentially inhibit the progression of neurodegenerative diseases. For example, Hsp70 overexpression in human neuroglioma cells transfected with mutant alpha-synuclein led to 50% less oligomeric alpha-synuclein species, pointing towards the possibility that increasing its expression could diminish the spread of Parkinson's disease. Similarly, Hsp70 overexpression suppressed poly-Q dependent aggregation and neurodegeneration in cell cultures, yeast, fly, and mouse models, and deletion of hsp70 increased the size of polyQ inclusion bodies, suggesting that increasing its expression could help to prevent Huntington's disease. Similarly, reductions in Hsp70 have been shown in transgenic mouse models of ALS and patients with sporadic ALS. Lastly, increased expression or activity of Hsp70 has been proposed as a method to prevent the progression of Alzheimer's disease, because knock down of Hsp70 promoted A-beta toxicity, and Hsp70 was shown to promote tau stability, while Hsp70 levels are decreased in tauopathies like Alzheimer's disease. Given the complex interplay between the different chaperone proteins, therapeutic development in this field is aimed at investigating how the chaperone network as a whole can be manipulated and the effect of this manipulation on the progression of neurodegenerative disease, but the balance of Hsp70 and Hsp90 levels appears to be central in this pathophysiology.
=== The Copa América final (1975) === The renamed and decentralised 1975 Copa América produced Colombia's first deep run in a continental tournament. Coached by Efraín Sánchez, the goalkeeper of the 1962 squad, Colombia won all four group matches against Paraguay and Ecuador, scoring seven and conceding one. In the semi-final they overwhelmed the defending champions Uruguay 3–0 at the Estadio El Campín through Edgar Angulo, Ortiz and Ernesto Díaz; the return at the Estadio Centenario finished 1–0 to Uruguay, whose Fernando Morena converted an early penalty before being sent off and whose team missed two further spot-kicks. With the sides level on points, Colombia advanced on goal difference. The final against Peru was the first in the competition's history to be decided over multiple legs. Ponciano Castro settled the opening match in Bogotá on 16 October with a long-range strike; Peru answered a week later at the Estadio Nacional in Lima, Juan Carlos Oblitas and Oswaldo Ramírez scoring inside the first half for a 2–0 win that levelled the tie on points and forced a decider on neutral ground. At the Estadio Olímpico in Caracas on 28 October, Hugo Sotil — flown in from Barcelona — scored the only goal before 30,000 spectators, and Peru claimed a second continental title. Ernesto Díaz finished as the tournament's joint leading scorer with four goals, a total that still ranks among the highest by a Colombian at the Copa América.
Sources: en.wikipedia.org
==== Antarctica ==== In 1982, Mahathir discussed the governance of Antarctica at the United Nations Convention on the Law of the Sea (UNCLOS). He emphasized that Antarctica should be regarded as the common heritage of mankind, opposing any unilateral claims of sovereignty and advocating for international cooperation in its management and resource utilization. At the time, there were concerns that minerals could be exploited in Antarctica, and the media regarded Mahathir's stance as the only political challenge ever mounted to the Antarctic Treaty in decades. In 1984, Mahathir stated that while the Antarctic Treaty system had contributed positively, there was a need to establish a broader foundation for international cooperation in Antarctica, and he proposed the formation of a "special committee on Antarctica" to conduct an in-depth study and build consensus on a new administrative framework for the continent and the mechanisms required to achieve it. Later, in October 1999, Malaysia sent four scientists to Antarctica to conduct research, focusing on air pollution as part of Universiti Malaya's air pollution research unit. Then, in November 2001, Malaysia launched a second mission, sending two scientists from Universiti Malaya to conduct research on marine and biological sciences. In February 2002, Mahathir led a Malaysian delegation, including his wife, Siti Hasmah Mohamad Ali, and several cabinet members, on a visit to Antarctica. They travelled from Ushuaia, Argentina, aboard the Russian icebreaker Kapitan Dranitsyn.
Nanofiltration Chromatography These extraction processes are considered "traditional processes" because they do not chemically affect the virus in any way; they simply remove it physically from the sample.
In February 2020, the FDA requested that the manufacturer of lorcaserin voluntarily withdraw the drug from the US market because a safety clinical trial showed an increased occurrence of cancer. The drug manufacturer, Eisai, voluntarily withdrew the drug.
Sources: en.wikipedia.org
=== Andy: Get The Poison Out === First aired: 4 November 2010 Meet Andy, the self-appointed king of Fresno. He is an obnoxious bully who makes life miserable for his victims, Steven and Taylor. He also makes the biggest mistake of calling out Mayhem, so Mayhem brings out "the greatest fighter he has ever known" to take care of Andy. That fighter turns out to be Mayhem himself. After easily being tapped out 5 times in the first round and knocked out in the second round, Steven and Taylor won $10,000. After the fight, Mayhem tells a humbled Andy that he had to deal with bullies most of his life and implores him to change his ways because he eventually will come across someone that is bigger, badder and meaner than Andy himself.
== Evolutionary Biology == The following tables compare the Homo sapiens FGFR1OP2 gene and protein to orthologs. In both of the following tables, the divergence from the Homo sapiens FGFR1OP2 gene or protein to the ortholog was found using TimeTree. Ortholog mRNA and protein sequences were found using NCBI's BLAST and UCSC's BLAT Tool. The accession numbers, as well as the sequence length and the sequence similarity were compiled using BLAST.
== Etymology == The genus name is from Late Latin falco meaning "falcon". The specific epithet sparverius is Medieval Latin for a "sparrowhawk". Until the sixth edition of the AOU Checklist of North American Birds was published by the American Ornithologists' Union in 1983, the most commonly used name for the American kestrel was the sparrow hawk. This was due to a mistaken connection with the Eurasian sparrowhawk in the genus Accipiter. The sixth edition of the AOU Checklist corrected this, officially renaming the bird American kestrel. Several other colloquial names for the kestrel are also in use, including grasshopper hawk, due to its diet, and killy hawk, due to its distinct call.
Sources: en.wikipedia.org
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.
Copper(II) complexes absorb light in the red part of the visible spectrum, so transmitted light appears blue. The absorption arises from electronic transitions within the copper d-orbitals, which are split by the surrounding ligands. The intensity and exact wavelength shift somewhat with pH, solvent, and ligand arrangement.
The free peptide and the copper-bound complex are studied as separate species and do not always behave the same way in assays. Some reported responses are attributed to copper delivery, while others are attributed to the peptide sequence itself. Which fraction drives a given observation is often unresolved in the published work.
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.