This is a working overview of RP-HPLC, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-09-10 and is reviewed periodically as new material appears.
Solid GHK-Cu appears as a blue to blue-violet powder, and the colour is a direct consequence of copper coordination. The complex dissolves readily in water and in many polar solvents, while the free peptide behaves differently. Solubility in nonpolar media is low, which limits its use in oil-based systems. Solutions are typically prepared fresh because the dissolved form is more exposed to hydrolysis and to loss of the metal ion than the dry powder. Working concentrations are usually low, and preparation notes often specify the solvent and the order of addition.
Dry material is typically held at low temperature, often around minus twenty degrees Celsius, and protected from moisture and light. Copper complexes can release their metal ion under acidic conditions or in the presence of competing chelators. Hydrolysis of the peptide backbone is a slower but real pathway, and the histidine residue is susceptible to oxidation over long periods. Stability statements therefore depend on formulation, pH, and container, and they should be read as conditional rather than absolute.
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.
| Property | Value | Notes |
|---|---|---|
| Solubility | Soluble in water | Free peptide differs from the complex |
| Typical storage | approx. −20 °C, desiccated | Protect from light and moisture |
| Primary purity method | RP-HPLC with MS | Confirms peptide identity |
| Copper assay | ICP-MS or AAS | Measured separately from peptide purity |
| Main degradation routes | Metal loss, hydrolysis, oxidation | Rate depends on pH and matrix |
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.
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.
Originally a Russian production, all in Russian with subtitles, produced by Maciej Drygas 15 October High Anxiety, about lifts and the required extensive technology of tall office buildings; Canary Wharf Tower (One Canada Square) had 50 floors with 36 lifts, which could travel up to 13.5 mph; Jim Fortune of Lerch Bates; novelist Philip Kerr; Otis Elevators alarm response centre of Farmington, Connecticut, which dealt with trapped passengers - it took about 20 minutes to rescue people; the Otis Test Tower, at Bristol in Connecticut, which had 29 floors and 11 lifts; architect Ken Yeang of Malaysia, known for his tall buildings; Gary Faltin of Otis; in the distant past, due to ropes, only goods were carried by lifts; in 1853 Elisha Otis invented a safety system for lifts, via a governor cable; only once have steel lift cables snapped, on 28 July 1945, in the 1945 Empire State Building B-25 crash after being lost in fog, severing the lift governor cable; if the cable snapped, due to the lift being balanced only after about nine people were in a lift, the lift would go upwards; on 12 August 1995, in the Empire State Building, a lift did go upwards, to be trapped at the 80th floor; the Woolworth Building, with 57 floors and 26 lifts, which could travel up to 10 mph - it was the world's tallest building from 1911 to 1930; engineer William Sheeran of Otis; medical doctor Rollin Stott, of the Linear Motion Laboratory of the Defence Research Agency (DERA) Centre for Human Sciences in north-east Hampshire; the feelings in the stomach, often sensed in a lift, comes from a pulse of adrenaline; Convent of Sacred Heart, with six floors; Nicole Fenchel was phobic of lifts; Doreen Powell of White Plains Hospital; the express lift, for the observation platform, in Tower 2 of the former World Trade Center had a journey time of 58 seconds; the former WTC had the world's second and third tallest office buildings; Tower 1 had 110 floors, being 417 metres high, with 96 lifts that could travel up to 15 mph; 70,000 people worked in the former WTC; people should not have to wait for a lift for no more than 30 seconds; Roger Howkins of Arup in London; 200 Vesey Street, known as Three World Financial Center, with 51 floors and 39 lifts, that could travel up to 14 mph; the former WTC was the first building to introduce the sky lobby design, with interspersed lifts; Robert DiChiara, assistant director of the former WTC; engineer Bruce Powell of Otis; Argentine architect, César Pelli, who designed One Canada Square of Canary Wharf; control systems of lifts anticipated demand; but there was a dark and menacing side to travel by lifts - Detectives Kevin Dineen and Lisa McClean of the NYPD Elevator Squad, at Carver Houses in the East Village, Manhattan, and how criminals could isolate victims; local youths and children would travel on top of the elevators for momentary thrills; the New York Marriott Marquis hotel, with 49 floors and 12 elevators, which could travel up to 15 mph; the Petronas Towers in Malaysia, with 88 floors, and 76 lifts, that could travel up to 16 mph, to be completed by 1997; lift ropes could go up to 600 metres, at the extreme most; new lifts would be powered by tubular linear motors or AC induction motors; 600 lifts with these new motors were operating in Japan; Yebisu Garden Place in Ebisu, Shibuya in Tokyo, where linear motors powered the lift counterweight; the Nishi-Shinjuku district in Shinjuku, Tokyo; many tall buildings were being built in Japan; Riverside Sumida Center, of Tokyo, built in 1994; the Yokohama Landmark Tower, with 70 floors, in Japan, built in 1993; Mitsubishi Electric had the world's fastest lifts, up to 28 mph; Junichi Sato of Mitsubishi, who said that he thought that Japanese people valued well-made products, and only trusted manufacturers too, whereas he thought that Americans and Europeans merely wanted functional products, whether good or not; the proposed enormous 800 metre Millennium Tower (Tokyo) for Tokyo Bay, with 150 floors, which was never built, but the Gherkin (30 St Mary Axe) was built instead; architect Andrew Miller of Foster Asia; there were twenty buildings over 60 floors being built; the Chinese economy was growing by 15% per year, and was Mitsubishi's biggest customer; the Century Tower (Tokyo), built in 1991, with 21 floors, with 14 lifts, that could travel up to 11 mph; lift technology had allowed Western business to prosper, but now it was superfluous for Western business. Narrated by Paul McGann, produced by Elizabeth Allen, directed by Gary Johnstone, made by Diverse Productions 22 October DNA in the Dock, an Equinox Special that was an update on the Incredible Evidence episode on 28 December 1994; The murder of 15-year-old Claire Hood, last seen on 19 January 1995, where 2,100 men had their DNA tested; her body was found in Cath Cobb Woods the next day; Sir Alec Jeffreys claimed that he could tell anyone apart; Timothy Wilson Spencer was the first person to be executed, with DNA evidence, on 27 April 1994, having committed murder in 1988; DCI Stuart Lewis, who worked on the Claire Hood investigation, who believed that her killer lived nearby - her killer lived 100 yards away; the United Kingdom National DNA Database began earlier in 1995, and in six months, 60,000 DNA specimens were recorded, and the database was intended to have 5 million specimens; an investigation of Orchid Cellmark, part of ICI, found that errors in correlation of specimens were made; California police gave test specimens to Cellmark, and errors were found, which Cellmark attributed to cross-contamination; Donald Findlay and a Scottish rape investigation in Largs, North Ayrshire, in 1987; former policeman Brian Kelly, and his wrongful conviction, for six years, serving four of them, for rape on 30 November 1989, through DNA evidence alone - DNA testing would later change in 1990, where crime scene DNA specimens were kept apart; Kary Mullis, who invented the PCR test in 1983, receiving the 1993 Nobel Prize in Chemistry, and knew about errors in DNA genetic testing; David Werrett of the Forensic Science Service, who set up the UK national DNA database in Birmingham, which deployed the PCR method - the more reliable Second Generation Multiplex Plus would be later introduced in 1999; Don Dovaston, later the deputy chief of Derbyshire Constabulary, which was the first police force to identify suspects through the UK DNA database; the Metropolitan Police had its own DNA database; Larry Mueller, population geneticist at the UCI School of Biological Sciences. Produced by David Poyser, directed by Hilary Lawson, made by TVF 5 November Kaboom!, the explosives engineer Sidney Alford; Controlled Demolition, Inc., founded by Jack Loizeaux; Rev Ron Lancaster, originally from Huddersfield, who founded Kimbolton Fireworks in 1964, when a chemistry teacher at Kimbolton School; in 1847 Ascanio Sobrero of Italy discovered nitroglycerin - nitroglycerin is the main component of dynamite; a detonation occurs at supersonic speed; Semtex was developed in Czechoslovakia in the 1960s; Ballistite, made from nitroglycerin and discovered in 1887, is the propellant for guns. Joint-production with NOVA and WGBH. Shown on Nova on 14 January 1997 12 November Avalanche, avalanches kill around two hundred people a year, with 120 of those in the Alps; Swiss physicist Othmar Buser of the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), who developed a database of avalanches; Bruce Tremper; Doug Fesler; powder snow avalanches can reach 150 mph; Laurent Buisson. Narrated by Heather Couper, made by Pioneer Productions with Discovery Networks 19 November God only Knows, about how some physicists see theology being explained through physics, such as Frank J. Tipler of Tulane University and his book The Physics of Immortality; George Johnson (writer) and book titles; Lewis Wolpert and how there was no evidence for God in the external world; David Finley of the National Radio Astronomy Observatory; religious writer Karen Armstrong, author of A History of God; Brazilian physicist Marcelo Gleiser; physicist Leon M. Lederman; Russell Stannard and physics before the big bang; the KTeV experiment at Fermilab, which looked at kaons, and Vivian O'Dell; Rev John Polkinghorne, former professor of Mathematical Physics at the University of Cambridge. Narrated by Bill Paterson, produced by Nicolas Kent, directed by Peter Webber 26 November Gloria's Toxic Death, about the death of Gloria Ramirez in California on 19 February 1994; a nurse, who took a blood sample from her, passed out from inhaling an unknown vapour coming from the blood sample; few episodes of Doctor Who had such a bizarre and unbelievable storyline; blood tests from the nurses revealed a lowering of the enzyme cholinesterase, which in other cases is linked to organophosphate poisoning; the Lawrence Livermore National Laboratory proposed a connection to dimethyl sulfoxide (DMSO) that had combined with oxygen given in the hospital to make dimethyl sulfate; the conditions of the hospital were repeated in a test, and the results underwent gas chromatography–mass spectrometry by Yolanda de Miguel at Department of Chemistry, Imperial College London. Narrated by Neil Pearson, directed by Tim Shawcross, produced by Geoff Deehan, made by Union Pictures with Discovery Communications 3 December On Jupiter, about the large gravitational effect that Jupiter has on the solar system; if the mass of Jupiter was thirty times bigger, the heat in its centre could sustain nuclear reactions, and it could become a star, maybe a brown dwarf; Gene Shoemaker of the Lowell Observatory and Palomar Observatory; Galileo Galilei discovered Jupiter's moons, Io, Europa, Ganymede (the largest moon in the solar system), and Callisto, on 7 January 1610; Heidi Hammel of MIT; Galileo (spacecraft), built at JPL and Ames in the 1980s, being planned to have launched in 1982, arrived at Jupiter on 7 December 1995; Torrence Johnson of JPL; Jim Scotti of the Spacewatch project at Kitt Peak National Observatory; Brian G. Marsden of the Central Bureau for Astronomical Telegrams; Vicki Meadows of the Anglo-Australian Telescope; Imke de Pater of the W. M. Keck Observatory on Mauna Kea; David Morrison (astrophysicist) of NASA Ames. Narrated by John Hurt, directed by Richard Smith, made by Pioneer Productions and the Discovery Channel 10 December Designing Dream Machines, about product innovation and product design of food processors and a reinvented motorbike by the Seymour-Powell design agency and its designer Nick Talbot, with the management team of Tefal UK and its managing director and a design by 43-year-old Dick Powell, and a possible new design of the ubiquitous 125CC BSA Bantam motorbike for MZ Motorrad- und Zweiradwerk of Germany by 42-year-old Richard Seymour; the 59 Club; Leigh Martin of the defunct Comet (closed in December 2012). Narrated by Marilyn Milgrom, directed by Richard Burke, produced by Richard Reisz. TV6 went on to make the six-part series Better by Design 17 December It Runs on Water, about the field commonly known as fringe science, where physicist Frank Close was sceptical if not broadly dismissive, stating that 300 years of science could not be overruled, but a professor of Aeronautics Paul Csysz of Saint Louis University mentioned that he thought some people in science were often unquestioning of their lifelong-held beliefs, and nervous of anyone trying to do so; an invention in Moscow was looked at by American physicist Harold E. Puthoff; Stanley Meyer's water fuel cell; NASA's propulsion research at Lewis Research Center in Cleveland, Ohio; it ends with Sir Arthur C. Clarke and Requiem (Mozart). Directed by Lawrence Simanowitz, produced and narrated by William Woollard, made by InCA Productions with Discovery Communications 20 December Do Vampire Bats have Friends?, an Equinox Special about whether animals have consciousness; zoologist Prof John Krebs, Baron Krebs, and whether animals had human-like sentience; biologist Gerald Wilkinson of the University of Maryland, and research, over five years, into relationships of vampire bats with other types of animals, and found food sharing between hungry vampire bats; zoologist Miriam Rothschild; psychologist Cecilia Heyes of UCL and self-perception of chimpanzees; zoologist Bernd Heinrich of the University of Vermont, and puzzle-solving of raven birds; zoologist Benjamin Beck of The National Zoo, and the apparent deployment of tools by animals; Ian Farquhar, and foxhunting, and whether foxes realise their predicament, and the Duke of Beaufort's Hunt in Gloucestershire; biologist Sir Patrick Bateson of the University of Cambridge, sensation of pain in animals, and the Animals (Scientific Procedures) Act 1986, which defined protected animals, that did not cover the octopus, but due to research by the Universities Federation for Animal Welfare (UFAW); Prof Peter Boyle and Martin Wells, and a 1993 amendment added the octopus; Prof Daniel Dennett of Tufts University, and how snakes think; psychologist Irene Pepper berg, of the University of Arizona, and an African Grey parrot called Alex, who has been talking for 18 years; the horse Clever Hans; Robert Seyfarth (scientist) and Dorothy Cheney (scientist), and their work on baboon warning calls and grunts, in Kenya. Narrated by Andrew Sachs, directed by Christopher Sykes, made by Christopher Sykes Productions
Alkanes with more than three carbon atoms can be arranged in various ways, forming structural isomers. The simplest isomer of an alkane is the one in which the carbon atoms are arranged in a single chain with no branches. This isomer is sometimes called the n-isomer (n for "normal", although it is not necessarily the most common). However, the chain of carbon atoms may also be branched at one or more points. The number of possible isomers increases rapidly with the number of carbon atoms. For example, for acyclic alkanes:
=== New owner === On 23 February 2023, Giant's operator Dairy Farm announced that it was exiting the grocery retail market in Malaysia, citing increasing competition. Dairy Farm's grocery business in Malaysia was sold to Macrovalue Sdn Bhd led by Andrew Lim Tatt Keong, a local businessman and entrepreneur. Dairy Farm, however, would still remain the operator of the Cold Storage and Giant franchise in Singapore until 2025, where it will be sold to Macrovalue Pte Ltd in March 2025. Following the acquisition, Macrovalue announced that Giant Hypermarket in both Singapore and Malaysia will be rebranded as Giant Mall as the parent company attempts to attract more foot traffic and cut down losses.
Sources: en.wikipedia.org
=== Outside Greece === Although frappés are commonly associated with Greece, their popularity has grown in other nations in the recent years. Frappés first became broadly known outside of Greece during the 2004 Summer Olympics in Athens, wherein many tourists became fond of them and an article was published in the Los Angeles Times. Immigrants and tourists in Greece have also helped to take the frappé abroad.
Fruit is produced only on mature plants. This takes 2–3 years for meter long cuttings and 3–4 years for 12 in cuttings or tissue cultures. The fruits are 15–23-centimetre-long (5.9–9.1 in) pods (often incorrectly called beans). Outwardly they resemble small bananas. They mature after about eight to nine months.
The season premiered on the streaming service Amazon Prime Video on June 3, 2022, with its first three episodes. The remaining five episodes were released weekly until July 8, 2022. The season received critical acclaim with praise towards its action sequences, social commentary, visual effects, character development, story, and performances (particularly Urban, Quaid, Starr, McElligott, Alonso, and Ackles). This season is widely regarded as the best season of the show. It received multiple nominations including two Primetime Creative Arts Emmy Awards, earning one for stunt coordination. On June 10, 2022, the series was renewed for a fourth season.
Sources: en.wikipedia.org
Unlike the other major plant hormones, ethylene is a gas and a very simple organic compound, consisting of just six atoms. It forms through the breakdown of methionine, an amino acid which is in all cells. Ethylene has very limited solubility in water and therefore does not accumulate within the cell, typically diffusing out of the cell and escaping the plant. Its effectiveness as a plant hormone is dependent on its rate of production versus its rate of escaping into the atmosphere. Ethylene is produced at a faster rate in rapidly growing and dividing cells, especially in darkness. New growth and newly germinated seedlings produce more ethylene than can escape the plant, which leads to elevated amounts of ethylene, inhibiting leaf expansion (see hyponastic response). As the new shoot is exposed to light, reactions mediated by phytochrome in the plant's cells produce a signal for ethylene production to decrease, allowing leaf expansion. Ethylene affects cell growth and cell shape; when a growing shoot or root hits an obstacle while underground, ethylene production greatly increases, preventing cell elongation and causing the stem to swell. The resulting thicker stem is stronger and less likely to buckle under pressure as it presses against the object impeding its path to the surface. If the shoot does not reach the surface and the ethylene stimulus becomes prolonged, it affects the stem's natural geotropic response, which is to grow upright, allowing it to grow around an object.
In FFF the display of detector signals as a function of time is called fractogram, in contrast to the chromatogram of column chromatography techniques. The fractogram can be converted to a distribution plot of one or several physical properties of the analyte using FFF theory and/or detector signals. This can be size, molar mass, charge, etc. Often these substances are particles initially suspended in a small volume of a liquid buffer and pushed along the FFF channel by the buffer. The varying velocities of a particular species of particles may be due to its size, its mass, and/or its distance from the walls of a channel with non-uniform flow-velocity. The presence of different species in a sample can thus be identified through detection of a common property at some distance down the long channel, and by the resulting fractogram indicating the presence of the various species by peaks, due to the different times of arrival characteristic of each species and its physical and chemical properties.
== Multimodal AI agents == In addition to large language models (LLMs), vision-language models (VLMs) and multimodal foundation models can be used as the basis for agents. Allen Institute for AI released an open-source vision-language model in 2024. Nvidia released a framework for developers to use VLMs, LLMs and retrieval-augmented generation for building AI agents that can analyze images and videos, including video search and video summarization. Microsoft released a multimodal agent model – trained on images, video, software user interface interactions, and robotics data – that the company claimed can manipulate software and robots.
=== Employee insider trading scandal === On the evening of September 29, 2016, Hanmi announced the Roche deal, causing its stock to rise; Hanmi was notified by Boehringer that evening that Boehringer was terminating their deal, and the company announced the termination on the morning of the 30th, causing its stock to crash. Hanmi's offices were raided by Korean regulatory authorities in mid-October based on evidence that insider knowledge of the Boehringer termination was passed to third parties, who shorted the stock prior to the announcement on the 30th. In December three Hanmi employees were among 17 people indicted for insider trading; 25 people were fined, and 45 people were found to have made illegal trades that took around 3.3 billion won ($2.83 million) in profits based on the information.
Sources: en.wikipedia.org
The colour comes from electronic transitions in the coordinated copper(II) ion. Ligand field effects absorb part of the visible spectrum. A colourless or greenish sample may indicate degraded material.
Copper can be displaced by other metal ions, by strong chelating agents, or by low pH. Samples exposed to these conditions may contain a mixture of free peptide and complex. Analytical testing is the only reliable way to confirm the bound fraction.
Solution storage generally shortens shelf life compared with the dry powder. Hydrolysis and oxidation proceed faster in aqueous media. Where solutions are used, cold storage and short holding times reduce measurable change.
GHK-Cu is a complex of the tripeptide glycyl-L-histidyl-L-lysine with copper(II). The peptide coordinates the metal through its histidine imidazole, terminal amino group, and amide nitrogen. It is studied in biochemistry and dermatological research.