This is a working overview of chromatographic purity, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-05-24. Anything still debated is marked as such rather than presented as settled.
Dry material is normally held cold, commonly at -20 °C for long-term storage and 2 to 8 °C for working quantities, protected from light and moisture. Vials should be allowed to reach room temperature before opening so that condensation does not form on the powder. In liquid formulations the complex is generally kept near neutral to slightly acidic pH, because strongly alkaline conditions favour precipitation of copper hydroxide. Antioxidants or chelate-stabilising excipients are often added, though the specific approaches are proprietary and rarely published in detail.
Identity and purity are assessed mainly by reversed-phase high-performance liquid chromatography with ultraviolet detection, often paired with mass spectrometry to confirm the expected mass. Copper content is measured separately by inductively coupled plasma optical emission spectrometry or atomic absorption spectroscopy, because the peptide assay alone does not establish the metal-to-peptide ratio. Visible spectroscopy provides a rapid check on complex integrity through the absorption band in the visible region. Agreement between the peptide assay and the copper assay is the practical test of whether a sample is the intended complex rather than a mixture.
Aqueous solutions of GHK-Cu are less stable than the dry powder. The peptide backbone is vulnerable to hydrolysis at extreme pH, and copper can be stripped from the complex by strong chelating agents such as EDTA or citrate. Oxidising agents and high concentrations of ascorbic acid can reduce copper(II) and change the complex, which is one reason formulators often keep such ingredients in separate phases. How quickly these changes occur under real storage conditions depends on pH, buffer, temperature and packaging, and quantitative data on the subject are limited.
Commercial products list GHK-Cu as copper tripeptide-1, a cosmetic ingredient. Formulators value its blue color and water solubility, which allow incorporation into serums, creams, and masks. Regulatory treatment varies: in the United States it appears in cosmetics, while some jurisdictions classify certain claims as drug-like. The compound is not an approved drug for any indication. Studies continue to examine its effects on skin, hair, and wound repair, but dosage, delivery, and long-term safety questions remain open.
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.
| Property | Value | Notes |
|---|---|---|
| Long-term storage | -20 °C | Dry powder, sealed and protected from light |
| Working storage | 2 to 8 °C | Short-term holding; avoid repeated warming cycles |
| Purity assay | Reversed-phase HPLC with UV detection | Detection commonly near 214 nm |
| Copper assay | ICP-OES or atomic absorption | Confirms metal content and the metal-to-peptide ratio |
| Visible absorption | Roughly 520 to 600 nm | Rapid indicator of complex integrity |
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.
GHK-Cu is a coordination complex formed between the peptide glycyl-L-histidyl-L-lysine and a copper(II) ion. The unbound chain, abbreviated GHK, consists of three amino acids and occurs naturally in human plasma, saliva, and urine. Binding of the metal is mediated mainly by the imidazole nitrogen of the histidine residue together with backbone amides, producing a stable chelate. Ingredient nomenclature often lists the same substance as copper tripeptide-1. Its charge and solubility behaviour differ from those of the metal-free chain.
Routine handling calls for minimizing freeze-thaw cycles and preparing solutions shortly before use. Glass or inert plastic containers reduce adsorption and metal leaching. Working stocks are often kept at 2–8 °C for short periods, while long-term reference material stays at −20 °C or below. Light protection is prudent because prolonged exposure may accelerate oxidation of the peptide. Documentation of lot number, concentration, and preparation date supports reproducibility in laboratory work.
Analytical verification typically combines reversed-phase high-performance liquid chromatography with ultraviolet-visible detection. The copper complex absorbs visible light near 600–630 nm, giving a characteristic blue signal. Mass spectrometry confirms molecular mass and can detect free peptide or mismatched copper stoichiometry. Copper content is often measured independently by inductively coupled plasma mass spectrometry or atomic absorption spectroscopy. Purity, counterion identity, and residual solvents are additional quality-control parameters that methods may address.
Solid GHK-Cu is generally stored as a dry powder under frozen conditions to limit degradation. The peptide bond can hydrolyze, and the copper center can be displaced by strong chelators such as EDTA. Aqueous solutions are less stable than the solid and may lose color or form precipitates over time. Temperature, pH, and oxygen exposure are the main variables that affect shelf life. Neutral to slightly acidic conditions tend to preserve the complex better than strongly alkaline media.
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.
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.
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.
Heritable connective tissue diseases are rare, each disorder estimated at one to ten per 100,000, of which Marfan syndrome is the most common. It is carried by the FBN1 gene on chromosome 15, which encodes the connective protein fibrillin-1, inherited as a dominant trait. This protein is essential for synthesis and maintenance of elastic fibers. Since these fibers are particularly abundant in the aorta, ligaments, and the ciliary zonules of the eye, these areas are among the worst affected. Everyone has a pair of FBN1 genes and, because transmission is dominant, those who have inherited one affected FBN1 gene from either parent will have Marfan syndrome. Although it is most frequently inherited as an autosomal dominant, there is no family history in 25% of cases. Recruiting practices aimed at attracting athletes who are unusually tall or who have an unusually wide arm span (characteristics of Marfan syndrome) can increase the prevalence of the syndrome within sports such as basketball and volleyball.
The stolon is ready to harvest two to three months after planting. It must be harvested before flowering. Harvesting the stolon is done by manual labor. For this step, the field is not drained. The stolon is pulled out of the water by pulling and shaking the young leaves in the shallow water. The first leaves and flowers can be harvested three months after planting. Flowers can be picked every two days during summer and every three days during the colder season. Four months after planting, the production of flowers has its climax. The harvest of flowers is usually done by hand for three to four months. Seeds and seed pods can be harvested when they turn black four to eight months after planting. After sun drying for two to three days, they are processed by mechanical tools to separate seed coats and embryos. The rhizomes mature to a suitable stage for eating in approximately six to nine months. Early varieties are harvested in July until September and late varieties from October until March, after the ponds or fields are drained. The large, starch-rich rhizomes are easy to dig out of the drained soil. In small-scale production, they are harvested by hand using fork-like tools. In Japan and on bigger farms, manual labour harvesting is fully replaced by machines.
== Drug interaction == The administration of cisplatin and vitamin B12 concomitantly does not modify the pharmacokinetics of the pemetrexed. It was recently shown that pemetrexed may play a role in cisplatin resistance in lung cancer by increasing the expression of Orai3 calcium channels as well as the expression of certain ABC transporters like MDR1 and MRP-5 responsible for cisplatin efflux and therefore a reduction of the effect of cisplatin As current therapies are based on the co-administration of pemetrexed and cisplatin, there may be interactions between pemetrexed and cisplatin, including a reduction in the therapeutic effects of cisplatin caused by pemetrexed.
== Biosynthesis == In the morphine biosynthetic pathway, salutaridinol is derived in three steps from (R)-reticuline. First, (R)-reticuline undergoes an oxidation at each of its phenol rings mediated by the cytochrome P-450-dependent monooxygenase salutaridine synthase. These phenol group oxidations yield a diradical species that undergoes ortho coupling to the phenol group of the tetrahydroisoquinoline and para coupling to the benzyl group to create the salutaridinol precursor salutaridine. A stereospecific reduction of the salutaridine carbonyl group by salutaridine: NADPH 7-oxidoreductase then generates salutaridinol.
Gene expression in mammals is regulated by many cis-regulatory elements, including core promoters and promoter-proximal elements that are located near the transcription start sites of genes, upstream on the DNA (towards the 5' region of the sense strand). Other important cis-regulatory modules are localized in DNA regions that are distant from the transcription start sites. These include enhancers, silencers, insulators and tethering elements. Enhancers and their associated transcription factors have a leading role in the regulation of gene expression. Enhancers are genome regions that regulate genes. Enhancers control cell-type-specific gene expression programs, most often by looping through long distances to come in physical proximity with the promoters of their target genes. Multiple enhancers, each often tens or hundred of thousands of nucleotides distant from their target genes, loop to their target gene promoters and coordinate with each other to control gene expression. The illustration shows an enhancer looping around to come into proximity with the promoter of a target gene. The loop is stabilized by a dimer of a connector protein (e.g. dimer of CTCF or YY1). One member of the dimer is anchored to its binding motif on the enhancer and the other member is anchored to its binding motif on the promoter (represented by the red zigzags in the illustration). Several cell function-specific transcription factors (among the about 1,600 transcription factors in a human cell) generally bind to specific motifs on an enhancer.
Sources: en.wikipedia.org
William Dale Archerd (May 5, 1912 – October 29, 1977) was an American serial killer who killed at least three people with insulin injections between 1956 and 1966 in Northern California. He was the first to be convicted of using insulin as a murder weapon in the US, and he is suspected in three more cases.
"Dépouillement des registres de la série V6E des Archives de la ville de Paris, échappés aux incendies de mai 1871" [Examination of the registers in series V6E of the Archives of the City of Paris, which escaped the fires of May 1871] (in French). Archived from the original on February 3, 2016. "Site des Archives départementales des Hauts-de-Seine" [Hauts-de-Seine Departmental Archives website] (in French). Archived from the original on June 14, 2016. "Site des Archives départementales de Seine-Saint-Denis" [Seine-Saint-Denis Departmental Archives website] (in French). Archived from the original on September 14, 2018. "Site des Archives départementales du Val-de-Marne" [Val-de-Marne Departmental Archives website] (in French). Archived from the original on March 18, 2018.
== Further reading == Schnug, E. (1998). Sulfur in Agroecosystems. Kluwer Academic Publishers, Dordrecht, 221 pp, ISBN 0-7923-5123-1. Grill, D., Tausz, M. and De Kok, L.J. (2001). Significance of Glutathione to Plant Adaptation to the Environment. Kluwer Academic Publishers, Dordrecht, ISBN 1-4020-0178-9. Abrol Y.P. and Ahmad A. (2003). Sulphur in Plants. Kluwer Academic Publishers, Dordrecht, ISBN 1-4020-1247-0. Saito, K., De Kok, L.J., Stulen, I., Hawkesford, M.J., Schnug, E., Sirko, A. and Rennenberg, H. (2005). Sulfur Transport and Assimilation in Plants in the Post Genomic Era. Backhuys Publishers, Leiden, ISBN 90-5782-166-4. Hawkesford, M.J. and De Kok, L.J. (2006). Managing sulfur metabolism in plants. Plant Cell and Environment. 29: 382–395.
Another major biological process and target of many chemotherapeutic drugs is the disruption of structures and genes involved in DNA replication, which would aim to reduce cancer cell proliferation and survival. However, through gene amplification, a resistance-inducing mechanism in which multiple copies of a gene are produced by cancer cells, the enhanced quantity of gene copy number limit the efficiency of such drugs, therefore allowing cancer cells to restore their proliferative ability and promote uncontrolled cell growth. A target enzyme known as topoisomerase II (Topo II) recognized for its fundamental role in detangling and repairing DNA, has also been proposed as a potentially promising site of action for drugs designed to induce DNA breakage. Here, it was suggested that the inhibition of Topo II would result in enzyme-mediated DNA breakage which without the proper functioning of repairment, would ultimately induce cell stress and apoptosis, or programmed cell death. As resistance to these Topo II poisons emerged, it was determined that cancer cells had developed mechanisms to reduce the expression of the Topo II enzyme, ultimately depriving these drugs from their targets and rendering them ineffective. Cancer cells have developed other resistance mechanisms to mediate the effects of chemotherapy-induced DNA breakage such as the activation of DNA damage repair (DDR) pathways which may recruit and upregulate various genes involved in DNA repair processes, thus countering the effects of many chemotherapeutic drugs.
All the secondary ions generated in SIMS analysis originate from the topmost monolayers of the bombarded solid. This means that all different modes of SIMS analysis are basically surface analysis; secondary-ion emissions—atomic as well as molecular—reflect the chemical composition of the near-surface region of the bombarded solid. However, the intention of different SIMS analyses may be quite different. This depends on the erosion rate of the surface, which is controlled by the dose of the primary ions. It may be bulk analysis (dynamic SIMS) or a true analysis of originally uppermost monolayer of a condensed phase (static SIMS).
Sources: en.wikipedia.org
==== Songs ==== "Chains" (Cookies song), 1962, covered by The Beatles "The Chain", a 1977 song by Fleetwood Mac "Chains", a song by Chicago from the 1982 album Chicago 16 "Chains" (Patty Loveless song), 1990 "Chain", a song by His Boy Elroy on their 1993 self-titled album. "Chains" (Tina Arena song), 1994 "Chains" (DLT song), 1996 "Chain", a song by the Fire Theft from their 2003 self-titled album "Chains" (Nick Jonas song), 2014 "Chains" (Usher song), 2015
The Constitution of India was drafted by the Constituent Assembly of India between 1946 and 1949, despite the political disruptions of the Partition. The Government of India Act 1935 was used as a model and framework. Long passages from the Act were included. The constitution describes a federal state with a parliamentary system of democracy. The federal structure was notable for the strength of the central government, which exclusively controlled defence, foreign affairs, railways, ports, and currency. The President, the constitutional head of state, has reserve powers for taking over the administration of a state. The central legislature has two houses: the Lok Sabha, whose delegates are directly elected by the people in general elections every five years, and the Rajya Sabha, whose members are nominated by the elected representatives in the states. The Constitution also includes features not found in the 1935 Act. The definition of fundamental rights is based on the Constitution of the United States, and the constitutional directives, or goals of endeavour, are based on the Constitution of Ireland. An Indian institution recommended by the constitution is the panchayat or village committees. Untouchability is illegal (Article 17) and caste distinctions are derecognised (Articles 15(2) and 16(2)). The promulgation of the Indian Constitution transformed India into a republic within the Commonwealth. The prime minister of India is the head of government and exercises most executive power.
By the early 1990s, Roche Biomedical became one of the largest clinical laboratory networks in the United States, with 20 major laboratories and US$600 million in sales. Roche has also produced various HIV tests and antiretroviral drugs. It bought the patents for the polymerase chain reaction (PCR) technique in 1992. In 1995, the era of highly active anti-retroviral therapy (HAART) was initiated by the United States FDA's approval of Hoffman LaRoche's HIV protease inhibitor, saquinavir. Within 2 years of its approval (and that of ritonavir 4 months later) annual deaths from AIDS in the United States fell from over 50,000 to approximately 18,000. On 28 April 1995, Hoffmann-La Roche sold Roche Biomedical Laboratories, Inc. to National Health Laboratories Holdings Inc. (which then changed its name to Laboratory Corporation of America Holdings). Roche acquired Syntex in 1994, and Chugai Pharmaceuticals in 2002. In 1998, Roche acquired Corange Ltd, the parent company of Boehringer Mannheim and DePuy Manufacturing for $11 billion. Boehringer Mannheim would be rebranded as Roche Diagnostics and DePuy was sold to Johnson & Johnson. Oseltamivir an antiviral drug used to combat influenza. Roche is the only drug company authorized to manufacture the drug, which was discovered by Gilead Sciences. Roche purchased the rights to the drug in 1996, and in 2005, settled a royalty dispute, agreeing to pay Gilead tiered royalties of 14–22% of annual net sales without adjusting the payments for manufacturing costs, as had been allowed in the original licensing agreement.
=== Protein structure determination === Characteristics indicative of the 3-dimensional structure of proteins can be probed with mass spectrometry in various ways. Comparing charge state distributions can give information about the structure of a protein. A wide variety of high charge states indicates disorder of the protein, whereas more compact, folded proteins result in lower charge states. By using chemical crosslinking to couple parts of the protein that are close in space, but far apart in sequence, information about the overall structure can be inferred. By following the exchange of amide protons with deuterium from the solvent, it is possible to probe the solvent accessibility of various parts of the protein. Hydrogen-deuterium exchange mass spectrometry has been used to study proteins and their conformations for over 20 years. This type of protein structural analysis can be suitable for proteins that are challenging for other structural methods. Another interesting avenue in protein structural studies is laser-induced covalent labeling. In this technique, solvent-exposed sites of the protein are modified by hydroxyl radicals. Its combination with rapid mixing has been used in protein folding studies.
Sources: en.wikipedia.org
Dry powder is best kept cold, dark and sealed, typically at -20 °C for long-term storage or 2 to 8 °C for material in regular use. Vials should be warmed to room temperature before opening to prevent moisture condensing on the contents. Aqueous stock solutions degrade faster and are usually prepared fresh.
The colour comes from electronic transitions between the copper ion and the surrounding peptide nitrogen atoms. The resulting absorption sits in the visible region, giving the solid and its solutions a blue to violet appearance. Loss of colour can indicate that the copper has dissociated from the peptide.
Chromatography establishes the identity and purity of the peptide, while elemental analysis establishes the copper content. The two results should agree with a one-to-one ratio. Visible spectroscopy adds a quick check that the complex itself is intact.
GHK is the free tripeptide, while GHK-Cu includes a bound copper(II) ion. The copper complex is the form most often studied for skin and wound-related activity. The two names are sometimes used interchangeably in product labeling, but they refer to distinct chemical species.