A practical reference on copper(II) complex: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2026-07-25 and is reviewed periodically as new material appears.
Several names circulate for the same material, which complicates literature searches. Cosmetic ingredient lists often use copper tripeptide-1, while older biochemistry papers use glycyl-L-histidyl-lysine or its abbreviation GHK. The copper complex is sometimes written as GHK-Cu(II) to make the oxidation state explicit. Terminology is not fully standardized, so matching a compound across sources requires attention to the exact sequence, the counterion, and the stated copper content. Reviews that compare studies must account for these naming differences before drawing conclusions.
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 copper-binding activity of this sequence was described in the 1970s during studies of liver tissue and plasma factors. Early work identified the peptide as a component that influenced copper uptake by cells and that appeared in wound fluid. Later investigations examined its presence across species, reporting the same chain in human and animal samples. A decline in measured concentration with age became a recurring observation, although the underlying causes remain incompletely characterised.
Published studies describe the complex in several research contexts, including collagen synthesis, antioxidant behaviour, and wound repair models. Much of this work is conducted in cultured cells or in small animal systems, and the findings are frequently cited in reviews of copper peptides. Direct clinical evidence in humans is comparatively limited, and reported outcomes vary with formulation and study design. Whether free chain or metal-bound form was used is not always stated, a point that complicates comparison between reports.
| Property | Value | Notes |
|---|---|---|
| Peptide sequence | Gly-His-Lys | Three amino acids, histidine in the middle |
| Complex formula | C14H22CuN6O4 | One copper(II) ion per peptide |
| Molar mass (complex) | approx. 402.9 g/mol | Depends on counterion and hydration state |
| Appearance | Blue to blue-violet solid | Colour arises from copper coordination |
| Common synonyms | Copper tripeptide-1, GHK-Cu | Naming varies between disciplines |
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.
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 commonly assessed by reversed-phase high-performance liquid chromatography, frequently paired with mass spectrometry to confirm the molecular ion. Copper content is measured separately, typically by inductively coupled plasma mass spectrometry or atomic absorption spectroscopy, because the chromatographic signal reports the peptide rather than the metal. Ultraviolet-visible spectroscopy provides a fast check on complex formation, since copper(II) peptide complexes absorb in the visible region. Elemental analysis and amino acid analysis are used less often but remain useful for reference standards. A gap between reported peptide purity and measured copper content is a recurring source of confusion.
Material described as GHK-Cu appears in several distinct markets, including cosmetic ingredients, laboratory reagents, and consumer products, and the quality expectations attached to each differ. A certificate of analysis generally reports peptide purity by chromatography, copper content, appearance, and residual solvents or counterions. Counterion identity matters, because the complex is usually supplied as an acetate or a similar salt, and the counterion contributes to the measured mass. Independent verification of sequence and metal stoichiometry is advisable when a material is used for quantitative work. Batch-to-batch variation is common and should be documented rather than assumed negligible.
GHK-Cu is the copper-binding complex formed by the tripeptide glycyl-L-histidyl-L-lysine and a copper(II) ion. The free peptide is usually written as GHK, and the complex is written as GHK-Cu or Cu-GHK. The sequence was identified in human plasma and later detected in saliva and urine. Its name comes from the single-letter codes of glycine, histidine and lysine. The complex is widely described as a naturally occurring carrier of copper in blood rather than as a free peptide with its own hormonal role.
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.
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.
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.
== Research == The combination drug dextromethorphan/quinidine (AVP-923), traditionally used to treat pseudobulbar affect, is under investigation for the treatment of a variety of other neurological and neuropsychiatric conditions including agitation associated with Alzheimer's disease, among others. In 2013, a randomized clinical trial found that dextromethorphan may reduce the overall discomfort and duration of withdrawal symptoms associated with opioid use disorder. When combined with clonidine, dextromethorphan reduced the overall time needed for withdrawal symptoms to peak by 24 hours while reducing severity of symptoms compared to clonidine alone.
About 20,000 protein-coding genes are expressed in human cells: 70% of these genes are expressed in thyroid cells. Two-hundred and fifty of these genes are more specifically expressed in the thyroid, and about 20 genes are highly thyroid specific. In the follicular cells, the proteins synthesized by these genes direct thyroid hormone synthesis—thyroglobulin, TPO, and IYD; while in the parafollicular c-cells, they direct calcitonin synthesis—CALCA, and CALCB.
=== Since 1873 === On January 1, 1873, Japan adopted the Gregorian calendar. To convert any Gregorian calendar year between 1873 and 1912 to Japanese calendar year in Meiji era, 1867 needs to be subtracted from the year in question.
== Immunity == The D. melanogaster immune system can be divided into two responses: humoral and cell-mediated. The former is a systemic response mediated in large part through the toll and Imd pathways, which are parallel systems for detecting microbes. Other pathways including the stress response pathways JAK-STAT and P38, nutritional signalling via FOXO, and JNK cell death signalling are all involved in key physiological responses to infection. D. melanogaster has an organ called the "fat body", which is analogous to the human liver. The fat body is the primary secretory organ and produces key immune molecules upon infection, such as serine proteases and antimicrobial peptides (AMPs). AMPs are secreted into the hemolymph and bind infectious bacteria and fungi, killing them by forming pores in their cell walls or inhibiting intracellular processes. The cellular immune response instead refers to the direct activity of blood cells (hemocytes) in Drosophila, which are analogous to mammalian monocytes/macrophages. Hemocytes also possess a significant role in mediating humoral immune responses such as the melanization reaction. The immune response to infection can involve up to 2,423 genes, or 13.7% of the genome. Although the fly's transcriptional response to microbial challenge is highly specific to individual pathogens, Drosophila differentially expresses a core group of 252 genes upon infection with most bacteria.
Sources: en.wikipedia.org
The life science business unit specializes in genomics, and involves the development of oligonucleotides, DNA polymerases, Real-time qPCR Probes, assay services, and proteomics. The proteomics operations are primarily concerned with custom peptides and antibodies, assay kits and Proprietary Dyes & Quenchers. The in vitro diagnostics business unit provides technical and project support for contract manufacturing of good manufacturing practice (GMP) Oligonucleotides and Taq DNA polymerases for use in Molecular Diagnostic applications. Manufacturing processes take place in clean rooms. The GMP BioManufacturing BU, is a full-service Contract Manufacturing Organization (CMO) and offers significant know-how in process development, technology transfer, formulation, scale-up and manufacturing of GMP proteins, protein conjugates, plasmids and bacterial vaccines for pre-clinical, clinical and commercial uses, all according to U.S. Food and Drug Administration (FDA) and EMA requirements.
Consumption of 1–1.5 grams (1,000–1,500 mg) per day is associated with a condition known as caffeinism. Caffeinism usually combines caffeine dependency with a wide range of unpleasant symptoms including nervousness, irritability, restlessness, insomnia, headaches, and palpitations after caffeine use. Caffeine overdose can result in a state of central nervous system overstimulation known as caffeine intoxication, a clinically significant temporary condition that develops during, or shortly after, the consumption of caffeine. This syndrome typically occurs only after ingestion of large amounts of caffeine, well over the amounts found in typical caffeinated beverages and caffeine tablets (e.g., more than 400–500 mg at a time). According to the DSM-5, caffeine intoxication may be diagnosed if five (or more) of the following symptoms develop after recent consumption of caffeine: restlessness, nervousness, excitement, insomnia, flushed face, diuresis, gastrointestinal disturbance, muscle twitching, rambling flow of thought and speech, tachycardia or cardiac arrhythmia, periods of inexhaustibility, and psychomotor agitation. According to the International Classification of Diseases (ICD-11), cases of very high caffeine intake (e.g. > 5 g) may result in caffeine intoxication with symptoms including mania, depression, lapses in judgment, disorientation, disinhibition, delusions, hallucinations or psychosis, and rhabdomyolysis.
Since the release of nonbenzodiazepines, also known as z-drugs, in 1992 in response to safety concerns, individuals with insomnia and other sleep disorders have increasingly been prescribed nonbenzodiazepines (2.3% in 1993 to 13.7% of Americans in 2010), and less often prescribed benzodiazepines (23.5% in 1993 to 10.8% in 2010). It is not clear as to whether the new non benzodiazepine hypnotics (Z-drugs) are better than the short-acting benzodiazepines. The efficacy of these two groups of medications is similar. According to the US Agency for Healthcare Research and Quality, indirect comparison indicates that side-effects from benzodiazepines may be about twice as frequent as from nonbenzodiazepines. Some experts suggest using nonbenzodiazepines preferentially as a first-line long-term treatment of insomnia. However, the UK National Institute for Health and Clinical Excellence did not find any convincing evidence in favor of Z-drugs. NICE review pointed out that short-acting Z-drugs were inappropriately compared in clinical trials with long-acting benzodiazepines. There have been no trials comparing short-acting Z-drugs with appropriate doses of short-acting benzodiazepines. Based on this, NICE recommended choosing the hypnotic based on cost and the patient's preference. Older adults should not use benzodiazepines to treat insomnia unless other treatments have failed.
== January 11, 1982 (Monday) == The lowest temperature ever recorded in England was measured at Newport, Shropshire, where the thermometer reading was −26.1 °C (−15.0 °F). Filming began on Return of the Jedi, the third film in the Star Wars franchise, and the conclusion of the original trilogy, with production starting at sound stages the Elstree Studios in England at Borehamwood, Hertfordshire. Born: Denis Kolodin, Russian footballer with 23 caps for the Russia national team; in Kamyshin, Russian SFSR, Soviet Union Blake Heron, American actor known for his starring role in the 1996 film Shiloh; in Rockville Centre, New York (d. from a drug overdose, 2017) Died: Jiro Horikoshi, Japanese aeronautical engineer who designed the Zero fighter. A. W. Haydon, 75, American inventor wand specialist in miniaturization, known for his invention of 82 devices and innovations, including the microswitch used in computers, as well other devices for use by the general public, by the U.S. military and by NASA Sir Kenneth Strong, 81, British Army Major General and advisor of the Normandy Landings on D-Day in 1944, as well as negotiating the surrender of both Italy and Japan Carl M. Voyles, 83, American Canadian football head coach for the Hamilton Tiger-Cats, known for guiding the team to winning the 1953 Grey Cup Manya Surve, 37, Indian gangster, suspected in multiple murders and robberies, became the first of 622 criminals in Bombay to die in an "encounter killing" by police in the Maharashtra state.
During the 1990s the National Arts Council was created to spearhead the development of performing arts, along with visual and literary art forms. The National Gallery Singapore is the nation's flagship museum with some 8,000 works from Singaporean and other Southeast Asian artists. The Singapore Art Museum focuses on contemporary art from a Southeast Asian perspective. The Red Dot Design Museum celebrates exceptional art and design of objects for everyday life, hosting more than 1,000 items from 50 countries. The lotus-shaped ArtScience Museum hosts touring exhibitions that combine art with the sciences. Other major museums include the Asian Civilisations Museum, the Peranakan Museum, and The Arts House. The Esplanade is Singapore's largest performing arts centre. In 2016 alone, it was the site of 5,900 free art and culture events. Literature of Singapore, or "SingLit", consists of a collection of literary works by Singaporeans written chiefly in the country's four official languages: English, Malay, Mandarin, and Tamil. Singapore is increasingly regarded as having four sub-literatures instead of one. Many significant works have been translated and showcased in publications such as the literary journal Singa, published in the 1980s and 1990s with editors including Edwin Thumboo and Koh Buck Song, as well as in multilingual anthologies such as Rhythms: A Singaporean Millennial Anthology Of Poetry (2000), in which the poems were all translated three times each.
Sources: en.wikipedia.org
The peptide is glycyl-L-histidyl-L-lysine, a three-amino-acid sequence commonly abbreviated GHK. It binds a single copper(II) ion under typical laboratory conditions. The free peptide and the copper complex are separate chemical species with different properties.
The sequence was identified in human plasma in 1973. Early work examined its presence in blood and its proposed role in tissue repair. The copper-binding property was characterized afterward and became the focus of much later research.
The tripeptide has been measured in human plasma and other biological fluids. Whether it circulates mainly as the copper complex or as the free peptide remains an open question. Natural concentrations are low and difficult to measure reliably.
GHK denotes the unbound chain of three amino acids. GHK-Cu describes the form in which a copper(II) ion is held by that chain. The two are not interchangeable in solution, since charge, molecular weight, and reactivity differ.