electron paramagnetic resonance raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2026-04-11. Anything still debated is marked as such rather than presented as settled.
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.
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.
Analytical verification commonly relies on high-performance liquid chromatography for purity assessment and mass spectrometry for identity confirmation. Spectroscopic methods such as UV-visible absorption and electron paramagnetic resonance can probe the metal centre itself, since the d9 configuration of copper(II) produces characteristic signals. Elemental analysis or plasma-based techniques quantify copper content. Because each method reports a different aspect of the same sample, purity figures are most meaningful when the technique and its detection wavelength are stated alongside the value.
| 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 |
Laboratory studies describe GHK-Cu as a source of copper that cells can take up, with reported effects on collagen, elastin, and glycosaminoglycan synthesis in cultured fibroblasts. The peptide also appears in wound-repair research, where it is linked to the activity of matrix metalloproteinases and their inhibitors. These observations come largely from cell and animal models. How directly the complex controls any single pathway in intact human skin remains an open question, and reported effects depend on concentration, vehicle, and exposure time.
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.
GHK-Cu is a coordination complex formed between the tripeptide glycyl-L-histidyl-L-lysine and copper(II). The peptide sequence consists of glycine, histidine, and lysine, and its imidazole and amino groups provide binding sites for the metal ion. In the complex, copper is held through nitrogen donors from the histidine side chain, the N-terminal amine, and deprotonated amide nitrogens. The resulting compound is intensely blue and water-soluble. It occurs naturally in human plasma, saliva, and urine at low concentrations.
The peptide was first isolated from human albumin in 1973 by Loren Pickart, who later described its copper-binding behavior. Early work linked the complex to wound healing and tissue remodeling. Plasma levels of GHK decline with age, a pattern that stimulated interest in topical and supplemental applications. Researchers have reported that the tripeptide influences collagen synthesis, antioxidant defense, and inflammatory signaling in cell and animal models. Human clinical evidence remains limited and often relies on small studies.
The company's first customers were educational institutions and life-sciences companies that were building supercomputers for purposes of drug discovery, computational fluid dynamics, genetic and genomic research, to predict response to drugs, and for COVID-19 research. Early customers included GlaxoSmithKline, AstraZeneca, the National Energy Technology Laboratory, Lawrence Livermore National Laboratory, the Pittsburgh Supercomputing Center, and Edinburgh Parallel Computing Centre. In September 2020, the company opened an office in Japan and partnered with Tokyo Electron. In April 2021, the company released its CS-2 system, based on the company's Wafer Scale Engine Two (WSE-2), which has 850,000 cores. The CS-2 is manufactured by the 7 nm process of TSMC. It is 26 inches (660 mm) tall and fits in one-third of a standard data center rack. The WSE-2 has 850,000 cores and 2.6 trillion transistors. It enables a single system to support AI models with more than 120 trillion parameters. The WSE-2 expanded on-chip SRAM to 40 gigabytes, memory bandwidth to 20 petabytes per second, and total fabric bandwidth to 220 petabits per second. Customers included TotalEnergies, nference, the National Center for Supercomputing Applications (NCSA), and the Leibniz Supercomputing Centre. In August 2021, Cerebras announced a partnership with Peptilogics on the development of AI for peptide therapeutics. In June 2022, Cerebras set a record for the largest AI models ever trained on one device—a single CS-2 system with one Cerebras wafer trained models with up to 20 billion parameters.
Long-term trends show that the district is less prone to violent crime than the rest of Toronto. Between 1997 and 2006, the proportion of violent crime committed in Scarborough averaged 20.4% despite its making up on average 23.6% of the city's total population over that period. Murder rates for the district and the rest of Toronto show no particular divergence. Between 1997 and 2006, the ratio of murders in Scarborough as compared to the rest of Toronto ranged from a low of 8.8% to a high of 32.2%. According to former Toronto Police Chief Bill Blair, "[42 Division is] the safest division in the city"; this division includes north Scarborough. In 2008, the safest part of Toronto was north Scarborough from Victoria Park Ave. to the Pickering border, north of Highway 401. In 2008, Toronto City Councillors Norm Kelly and Michael Thompson protested that the media was distorting how crime was reported in Scarborough. They noted that whenever a shooting occurred in the rest of the city the location was given as the nearest major intersection, while when a shooting happened in Scarborough the location was given as 'Scarborough'. According to the councillors, this gave people an erroneous impression of Scarborough as 'crime-ridden'. They proposed that news outlets sign a 'media protocol' so that all crime locations were given as intersections. However, the city's executive committee turned down the request citing this as a form of censorship. Mayor David Miller said "It's not city council's role to tell the media how to do their job".
From the first partition of Poland (1772): Polish Inflants (Latgale), the northern part of the Polotsk Voivodeship, the entire Mstsislaw Voivodeship and Vitebsk Voivodeships, and the southeastern part of the Minsk Voivodeship (about 92,000 km2) From the second partition of Poland (1793): the remaining part of the Minsk Voivodeship, the entire Kiev Voivodeship, Bracław Voivodeship and Vilnius Voivodeships, parts of Podole Voivodeship and eastern parts of the Wołyń Voivodeship and Brest Litovsk Voivodeships (about 250,000 km2) From the third partition of Poland (1795): all the territories east of the Bug River(about 120,000. km2) and after 1807 the Belostok Oblast) It consisted of 9 guberniyas: six Belarusian and Lithuanian ones that constituted the Northwestern Krai (Vilna Governorate, Kovno Governorate, Grodno Governorate, Minsk Governorate, Mogilev Governorate and Vitebsk Governorate) and three Ukrainian ones that constituted the Southwestern Krai (Volhynia Governorate, Podolia Governorate and Kiev Governorate). In the first partition, Russia gained 92,000 km2 and 1.3 million people. In the second, 250,000 km2 and 1 million people. In the third, 120,000 km2 and 1.2 million people. Overall, Russia had gained about 62 percent of the former Commonwealth territory (462,000 km2) and about 45 percent of the population (3.5 million people). The Russian partition was thus the largest and most populous of the three partitions (the other two being the Austrian Partition and the Prussian Partition).
Sources: en.wikipedia.org
Sweating allows the body to regulate its temperature. Sweating is controlled from a center in the preoptic and anterior regions of the brain's hypothalamus, where thermosensitive neurons are located. The heat-regulatory function of the hypothalamus is also affected by inputs from temperature receptors in the skin. High skin temperature reduces the hypothalamic set point for sweating and increases the gain of the hypothalamic feedback system in response to variations in core temperature. Overall, however, the sweating response to a rise in hypothalamic ('core') temperature is much larger than the response to the same increase in average skin temperature. Sweating causes a decrease in core temperature through evaporative cooling at the skin surface. As high energy molecules evaporate from the skin, releasing energy absorbed from the body, the skin and superficial vessels decrease in temperature. Cooled venous blood then returns to the body's core and counteracts rising core temperatures. There are two situations in which the nerves will stimulate the sweat glands, causing perspiration: during physical heat and during emotional stress. In general, emotionally induced sweating is restricted to palms, soles, armpits, and sometimes the forehead, while physical heat-induced sweating occurs throughout the body. Human sweat is not pure water; though it contains no protein, it always contains a small amount (0.2–1%) of solute. When a person moves from a cold climate to a hot climate, adaptive changes occur in the sweating mechanisms of the person.
=== APOA-I: A Possible Novel Biomarker for Metabolic Side Effects in First Episode Schizophrenia === The authors of this study sought to determine the effect on metabolism of the drug risperidone in schizophrenia patients. After discovering that risperidone did have negative metabolic side effects, they tested membrane proteins for glucose and lipid transport in control and experimental groups by MALDI-TOF and fingerprinting. Results showed altered fingerprints and therefore altered levels of folding in the proteins. So, they concluded that risperidone negatively effects glucose and lipid transport proteins in the cell membranes of patients.
Aberrant basal cell carcinoma Acanthoma fissuratum (granuloma fissuratum, spectacle frame acanthoma) Acrospiroma (clear cell hidradenoma, dermal duct tumor, hidroacanthoma simplex, nodular hidradenoma, poroma) Actinic keratosis (senile keratosis, solar keratosis) Adenoid squamous cell carcinoma (pseudoglandular squamous cell carcinoma) Aggressive digital papillary adenocarcinoma (digital papillary adenocarcinoma, papillary adenoma) Apocrine gland carcinoma Apocrine nevus Arsenical keratosis Atrophic actinic keratosis Balanitis plasmacellularis (balanoposthitis chronica circumscripta plasmacellularis, balanitis circumscripta plasmacellularis, plasma cell balanitis, plasma cell vulvitis, vulvitis circumscripta plasmacellularis, Zoon's balanitis, Zoon's erythroplasia, Zoon's vulvitis) Basal cell carcinoma Basaloid follicular hamartoma Basaloid squamous cell carcinoma Birt–Hogg–Dubé syndrome Bowen's disease (squamous cell carcinoma in situ) Brooke–Fordyce syndrome Ceruminoma Cicatricial basal cell carcinoma (morpheaform basal cell carcinoma, morphoeic basal cell carcinoma) Ciliated cyst of the vulva (cutaneous Müllerian cyst, paramesonephric mucinous cyst of the vulva) Clear cell acanthoma (acanthome cellules claires of Degos and Civatte, Degos acanthoma, pale cell acanthoma) Clear cell squamous cell carcinoma (clear cell carcinoma of the skin) Chronic scar keratosis (chronic cicatrix keratosis) Clonal seborrheic keratosis Common seborrheic keratosis (basal cell papilloma, solid seborrheic keratosis) Cowden syndrome (Cowden's disease, multiple hamartoma syndrome) Cutaneous ciliated cyst Cutaneous columnar cyst Cutaneous horn (Cornu cutaneum) Cystic basal cell carcinoma Dermal eccrine cylindroma (cylindroma) Dermatosis papulosa nigra Desmoplastic trichoepithelioma Dilated pore (dilated pore of Winer) Eccrine carcinoma (syringoid carcinoma) Eccrine nevus Epidermal cyst (epidermal inclusion cyst, epidermoid cyst, infundibular cyst, keratin cyst) Epidermal nevus syndrome (Feuerstein and Mims syndrome, Solomon's syndrome) Epidermolytic acanthoma Epithelioma cuniculatum (Ackerman tumor, carcinoma cuniculatum) Eruptive vellus hair cyst Erythroplasia of Queyrat Extramammary Paget's disease Fibroepithelioma Fibroepithelioma of Pinkus Fibrofolliculoma Follicular hybrid cyst (Hybrid cyst) Folliculosebaceous-apocrine hamartoma (follicular-apocrine hamartoma) Folliculosebaceous cystic hamartoma Generalized eruptive keratoacanthoma (generalized eruptive keratoacanthoma of Grzybowski) Giant solitary trichoepithelioma Hidradenoma Hidradenocarcinoma Hidrocystoma (cystadenoma, Moll's gland cyst, sudoriferous cyst) Hydrocarbon keratosis (pitch keratosis, tar keratosis, tar wart) Hyperkeratosis lenticularis perstans (Flegel's disease) Hyperkeratosis of the nipple and areola Hyperkeratotic actinic keratosis Ichthyosis hystrix (ichthyosis hystrix gravior type Lambert, porcupine man, systematized verrucous nevus) Ichthyosis hystrix of Curth–Macklin Infiltrative basal cell carcinoma Inflammatory linear verrucous epidermal nevus Inverted follicular keratosis Irritated seborrheic keratosis (basosquamous cell acanthoma, inflamed seborrheic keratosis) Isthmicoma (infundibuloma, tumor of the follicular infundibulum) Juvenile myelomonocytic leukemia Keratin implantation cyst Keratoacanthoma Keratoacanthoma centrifugum marginatum Large cell acanthoma Lichenoid actinic keratosis Lichenoid keratosis (benign lichenoid keratosis, lichen planus-like keratosis, solitary lichen planus, solitary lichenoid keratosis) Linear verrucous epidermal nevus (linear epidermal nevus, verrucous epidermal nevus) Malignant acrospiroma (spiradenocarcinoma) Malignant mixed tumor (malignant chondroid syringoma) Malignant trichilemmal cyst Mantleoma Marjolin's ulcer Melanoacanthoma (pigmented seborrheic keratosis) Merkel cell carcinoma (cutaneous apudoma, primary neuroendocrine carcinoma of the skin, primary small cell carcinoma of the skin, trabecular carcinoma of the skin) Microcystic adnexal carcinoma (sclerosing sweat duct carcinoma) Micronodular basal cell carcinoma Milia en plaque Milium Mixed tumor (chondroid syringoma) Mucinous carcinoma Mucinous nevus (nevus mucinosus) Muir–Torre syndrome Multiple familial trichoepithelioma (Brooke–Spiegler syndrome, epithelioma adenoides cysticum) Multiple keratoacanthomas (Ferguson–Smith syndrome, Ferguson-Smith type of multiple self-healing keratoacanthomas, multiple keratoacanthomas of the Ferguson–Smith type) Multiple minute digitate hyperkeratosis (digitate keratoses, disseminated spiked hyperkeratosis, familial disseminated piliform hyperkeratosis, minute aggregate keratosis) Nevoid basal cell carcinoma syndrome (basal cell nevus syndrome, Gorlin syndrome, Gorlin–Goltz syndrome) Nevus comedonicus (comedo nevus) Nevus comedonicus syndrome Nevus sebaceous (nevus sebaceous of Jadassohn, organoid nevus) Nevus unius lateris Nodular basal cell carcinoma (classic basal cell carcinoma) Paget's disease of the breast Papillary eccrine adenoma (tubular apocrine adenoma) Papillary hidradenoma (hidradenoma papilliferum) Papillomatosis cutis carcinoides (Gottron's carcinoid papillomatosis, papillomatosis cutis carcinoides of Gottron–Eisenlohr) Patch blue nevus (acquired dermal melanocytosis, dermal melanocyte hamartoma) Perifollicular fibroma Phakomatosis pigmentokeratotica Pigmented actinic keratosis Pigmented basal cell carcinoma Pigmented hairy epidermal nevus syndrome Pilar sheath acanthoma Pilonidal sinus (Barber's interdigital pilonidal sinus, pilonidal cyst, pilonidal disease) Porocarcinoma (malignant poroma, eccrine porocarcinoma) Polypoid basal cell carcinoma Pore-like basal cell carcinoma Primary cutaneous adenoid cystic carcinoma Proliferating epidermoid cyst (proliferating epithelial cyst) Proliferating trichilemmal cyst (pilar tumor, proliferating follicular cystic neoplasm, proliferating pilar tumor, proliferating trichilemmal tumor) Pseudocyst of the auricle (auricular endochondrial pseudocyst, cystic chondromalacia, endochondral pseudocyst, intracartilaginous cyst) Pseudoepitheliomatous keratotic and micaceous balanitis PUVA keratosis Rasmussen syndrome Reactional keratosis Reticulated seborrheic keratosis (adenoid seborrheic keratosis) Rodent ulcer (Jacobi ulcer) Schimmelpenning syndrome (Schimmelpenning–Feuerstein–Mims syndrome) Sebaceoma (sebaceous epithelioma) Sebaceous adenoma Sebaceous carcinoma Sebaceous hyperplasia Sebaceous nevus syndrome Seboacanthoma Seborrheic keratosis (seborrheic verruca, senile wart) Seborrheic keratosis with squamous atypia Signet-ring cell squamous cell carcinoma Solitary keratoacanthoma (subungual keratoacanthoma) Solitary trichoepithelioma Spindle cell squamous cell carcinoma (spindle cell carcinoma) Spiradenoma Squamous cell carcinoma Steatocystoma multiplex (epidermal polycystic disease, sebocystomatosis) Steatocystoma simplex (simple sebaceous duct cyst, solitary steatocystoma) Stucco keratosis (digitate seborrheic keratosis, hyperkeratotic seborrheic keratosis, keratosis alba, serrated seborrheic keratosis, verrucous seborrheic keratosis) Superficial basal cell carcinoma (superficial multicentric basal cell carcinoma) Syringadenoma papilliferum (syringocystadenoma papilliferum) Syringofibroadenoma (acrosyringeal nevus of Weedon and Lewis) Syringoma Systematized epidermal nevus Thermal keratosis Trichilemmal carcinoma Trichilemmal cyst (isthmus-catagen cyst, pilar cyst) Trichilemmoma Trichoadenoma (trichoadenoma of Nikolowski) Trichoblastoma Trichoblastic fibroma Trichodiscoma Trichofolliculoma Unilateral palmoplantar verrucous nevus Urethral caruncle Verrucous carcinoma Verrucous cyst (cystic papilloma) Viral keratosis Warty dyskeratoma (isolated dyskeratosis follicularis) Waxy keratosis of childhood (kerinokeratosis papulosa) Zoon's vulvitis Zosteriform speckled lentiginous nevus
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.
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.