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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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Copper(II) peptide complex | Peptide chain coordinated to a single metal ion |
| CAS number | 89030-95-5 | Indexed for the peptide-copper complex |
| Molecular formula | C14H22CuN6O4 | Approximate formula for a one-to-one complex |
| Appearance | Blue to violet solid | Color from copper d-d transitions |
| Solubility class | Freely soluble in water | Also dispersible in some polar solvents |
Solutions of GHK-Cu respond strongly to pH, redox conditions, and the presence of competing chelators such as EDTA. Below roughly pH 4 the copper tends to dissociate, because the amide nitrogen donors become protonated and can no longer coordinate. Strongly alkaline conditions instead favour hydrolysis and precipitation of copper hydroxide. Dissolved oxygen and light accelerate breakdown of the peptide backbone, and the copper released during that process can catalyse further oxidation, so dry, cold, dark storage is the usual recommendation.
Routine characterisation relies on reversed-phase high-performance liquid chromatography for peptide purity, paired with mass spectrometry for identity confirmation. Ultraviolet-visible spectroscopy detects the metal centre through its absorption band in the visible region, and inductively coupled plasma mass spectrometry quantifies total copper so that a metal-to-peptide ratio can be calculated. Amino acid analysis confirms the expected residue composition. Together these techniques establish concentration, identity, and stoichiometry, but none of them directly reports biological activity.
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.
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.
== Symmetry == During the 19th century crystallography was progressively transformed into an empirical and mathematical science by the adoption of symmetry concepts. In 1832 Franz Ernst Neumann used symmetry considerations when studying double refraction in crystals. Woldemar Voigt, who was a student of Neumann, in 1885 formalized Neumann's principle as "if a crystal is invariant with respect to certain symmetry operations, any of its physical properties must also be invariant with respect to the same symmetry operations". Neumann's principle is sometimes referred to as the Neumann–Minnigerode–Curie principle based on later work by Bernhard Minnigerode (another student of Neumann) and Pierre Curie. Curie's principle "the symmetries of the causes are to be found in the effects" is a generalization of Neumann's principle. The relations between symmetry and physical and chemical properties were established throughout the 19th century: the notion of hemihedry (Weiss, 1819; Delafosse, 1840), the 7 crystal systems (Mohs, 1822), the notion of point lattice (Seeber, 1824), the 32 crystal classes (Frankenheim, 1826; Hessel, 1830; Gadolin, 1869), molecular chirality (Pasteur, 1848), the 14 Bravais lattices (Bravais, 1850), the 65 chiral groups that contain only proper symmetry operations – rotations, translations and roto-translations (Sohncke 1879), and, finally, the 230 space groups (Fedorov, 1891; Schoenflies, 1891; Barlow, 1894).
Deoxyribonucleic acid (; DNA) is a polymer composed of two polynucleotide chains that coil around each other to form a double helix. The polymer carries genetic instructions for the development, functioning, growth and reproduction of all known organisms and many viruses. DNA and ribonucleic acid (RNA) are nucleic acids. Alongside proteins, lipids and complex carbohydrates (polysaccharides), nucleic acids are one of the four major types of macromolecules that are essential for all known forms of life. The two DNA strands are known as polynucleotides as they are composed of simpler monomeric units called nucleotides. Each nucleotide is composed of one of four nitrogen-containing nucleobases (cytosine [C], guanine [G], adenine [A] or thymine [T]), a sugar called deoxyribose, and a phosphate group. The nucleotides are joined to one another in a chain by covalent bonds (known as the phosphodiester linkage) between the sugar of one nucleotide and the phosphate of the next, resulting in an alternating sugar-phosphate backbone. The nitrogenous bases of the two separate polynucleotide strands are bound together, according to base pairing rules (A with T and C with G), with hydrogen bonds to make double-stranded DNA. The complementary nitrogenous bases are divided into two groups, the single-ringed pyrimidines and the double-ringed purines. In DNA, the pyrimidines are thymine and cytosine; the purines are adenine and guanine. Both strands of double-stranded DNA store the same biological information. This information is replicated when the two strands separate.
=== Controversy of term === There is debate on whether the term "cyber warfare" is accurate. In 2012, Eugene Kaspersky, founder of Kaspersky Lab, concluded that "cyberterrorism" is a more accurate term than "cyberwar." He states that "with today's attacks, you are clueless about who did it or when they will strike again. It's not cyber-war, but cyberterrorism." Howard Schmidt, former Cyber Security Coordinator in the Obama administration, said that "there is no cyberwar... I think that is a terrible metaphor and I think that is a terrible concept. There are no winners in that environment." Some experts take issue with the possible consequences linked to the warfare goal. In 2011, Ron Deibert, of Canada's Citizen Lab, warned of a "militarization of cyberspace", as militaristic responses may not be appropriate. However, to date, even serious cyber-attacks that have disrupted large parts of a nation's electrical grid (230,000 customers, Ukraine, 2015) or affected access to medical care, thus endangering life (UK National Health Service, WannaCry, 2017) have not led to military action. In 2017, Oxford academic Lucas Kello proposed a new term, "Unpeace", to denote highly damaging cyber actions whose non-violent effects do not rise to the level of traditional war. Such actions are neither warlike nor peace-like. Although they are non-violent, and thus not acts of war, their damaging effects on the economy and society may be greater than those of some armed attacks.
Spectroscopy with a variable pathlength cell takes advantage of Beer–Lambert law to determine concentrations of various solutions. By knowing the molar absorptivity of the material and varying the path length, absorption can be plotted as a function of path length. See sample plot to the right: By taking a linear regression of the linear plot above an expression relating Absorbance, A, slope, m, pathlength and concentration can be derived. A linear equation of two variables can be derived,
Arizona, 5.53% (187,382 votes) – 11 electoral votes Virginia, 5.78% (260,310 votes) – 13 electoral votes New Jersey, 5.91% (252,498 votes) – 14 electoral votes New Mexico, 6.00% (55,411 votes) – 5 electoral votes Maine, 6.94% (57,514 votes) – 2 electoral votes Maine's 2nd congressional district, 9.03% (33,297 votes) – 1 electoral vote Red denotes states or congressional districts won by Republican Donald Trump; Blue denotes those won by Democrat Kamala Harris.
Sources: en.wikipedia.org
Eastern Theater Command Southern Theater Command Western Theater Command Northern Theater Command Central Theater Command The service headquarters retain operational control in some areas within China and outside of China. For example, army headquarters controls or is responsible for the Beijing Garrison, the Tibet Military District, the Xinjiang Military District, and border and coastal defences. The counterpiracy patrols in the Gulf of Aden are controlled by navy headquarters. The JSD nominally controls operations beyond China's periphery, but in practice this seems to apply only to army operations. Services and theater commands have the same grade. The overlap of areas or units of responsibility may create disputes requiring CMC arbitration. As part of the 2015 reforms, military regions were replaced by theatre commands in 2016. Military regions were − uinlike the theatre commands − army-centric peacetime administrative organizations, and joint wartime commands were created on-demand by the army-dominated General Staff Department.
== In drug discovery == Identification of active sites is crucial in the process of drug discovery. The 3-D structure of the enzyme is analysed to identify active site residues and design drugs which can fit into them. Proteolytic enzymes are targets for some drugs, such as protease inhibitors, which include drugs against AIDS and hypertension. These protease inhibitors bind to an enzyme's active site and block interaction with natural substrates. An important factor in drug design is the strength of binding between the active site and an enzyme inhibitor. If the enzyme found in bacteria is significantly different from the human enzyme then an inhibitor can be designed against that particular bacterium without harming the human enzyme. If one kind of enzyme is only present in one kind of organism, its inhibitor can be used to specifically wipe them out. Active sites can be mapped to aid the design of new drugs such as enzyme inhibitors. This involves the description of the size of an active site and the number and properties of sub-sites, such as details of the binding interaction. Modern database technology called CPASS (Comparison of Protein Active Site Structures) however allows the comparison of active sites in more detail and the finding of structural similarity using software.
Cancer is the uncontrolled growth of cells coupled with malignant behaviour: invasion and metastasis (among other features). It is caused by the interaction between genetic susceptibility and environmental factors. These factors lead to accumulations of genetic mutations in oncogenes (genes that control the growth rate of cells) and tumor suppressor genes (genes that help to prevent cancer), which gives cancer cells their malignant characteristics, such as uncontrolled growth. In the broad sense, most chemotherapeutic drugs work by impairing mitosis (cell division), effectively targeting fast-dividing cells. As these drugs cause damage to cells, they are termed cytotoxic. They prevent mitosis by various mechanisms including damaging DNA and inhibition of the cellular machinery involved in cell division. One theory as to why these drugs kill cancer cells is that they induce a programmed form of cell death known as apoptosis. As chemotherapy affects cell division, tumors with high growth rates (such as acute myelogenous leukemia and the aggressive lymphomas, including Hodgkin's disease) are more sensitive to chemotherapy, as a larger proportion of the targeted cells are undergoing cell division at any time. Malignancies with slower growth rates, such as indolent lymphomas, tend to respond to chemotherapy much more modestly. Heterogeneic tumours may also display varying sensitivities to chemotherapy agents, depending on the subclonal populations within the tumor. Cells from the immune system also make crucial contributions to the antitumor effects of chemotherapy.
where ± refers to a positive or negative particle, Ip is the incident ion current, f±i is the fraction of particles sputtered as ions, Si is the sputtering yield of both ions and neutrals, Ci is the concentration of the ith element (corrected for isotopic abundance) in the sputtered volume, ηi is the collection efficiency of the SIMS instrument, Ip = d2j/4, d is the diameter of a Gaussian-shaped beam, and j is the current density.
Sources: en.wikipedia.org
It is the copper complex of the tripeptide glycyl-L-histidyl-lysine. The metal ion is held by the histidine imidazole group and the peptide N-terminus. Most research on it concerns skin and wound models.
The tripeptide was first isolated from human plasma and has also been reported in saliva and urine. Plasma levels appear to decline with age in some small studies. Those observations rest on limited sample sizes.
It is not authorized as a systemic medicine in most countries. Cosmetic preparations list it as an ingredient rather than an active pharmaceutical substance. Legal status therefore differs by jurisdiction.
It is not approved as a pharmaceutical in major markets and is used mainly as a cosmetic ingredient and a laboratory reagent. Regulatory status varies by country and by the product category in which it appears. Claims about therapeutic effects should be treated separately from permitted cosmetic labeling.