If you have been reading about tripeptide and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2026-01-09. Numbers and descriptions here follow the published literature rather than marketing material.
GHK-Cu is a coordination complex formed between the tripeptide glycyl-L-histidyl-L-lysine and a copper(II) ion. The peptide was isolated from human plasma in the early 1970s by Loren Pickart, who observed that a plasma fraction from young donors stimulated growth in cultured liver cells. The copper-bound form is abbreviated GHK-Cu, while the metal-free peptide is written simply as GHK. In the research literature the complex also appears as copper tripeptide-1 and as glycyl-histidyl-lysine copper complex.
Copper(II) binds the peptide through four nitrogen donors: the terminal amino group, the imidazole nitrogen of histidine, and two deprotonated amide nitrogens of the peptide backbone. This tetradentate arrangement gives a roughly square-planar geometry, the thermodynamically favoured form near neutral pH. Because the amide nitrogens must lose a proton before they can coordinate, complex formation is strongly pH-dependent, and the fully coordinated species dominates only above mildly acidic conditions. Electronic transitions within the copper d orbital set produce the characteristic blue to violet colour in aqueous solution.
Endogenous GHK occurs in blood plasma, saliva, and urine, and reported plasma concentrations decline with age in several studies. Researchers have proposed that the peptide acts as a copper carrier that delivers the metal to cells and to sites of injury. That transport role is a hypothesis supported by binding measurements and tissue-distribution data rather than a settled mechanism, and the peptide is generally described as a minor contributor to total plasma copper transport. Values reported in wound fluid and certain tissue extracts are higher than in circulating plasma.
Quality specifications for research material commonly state peptide purity, copper stoichiometry, counter-ion identity, and residual water content. Frequent counter-ions include acetate and trifluoroacetate, which differ in mass and in their effect on solubility and handling. Whether batch-to-batch differences in reported responses trace to these parameters or to assay conditions remains an open question, since published comparisons rarely control for all of them at once. Independent verification therefore normally pairs a purity measurement with an elemental copper measurement on the same lot.
Practical handling notes centre on limiting exposure to water, oxygen, and repeated temperature cycling. Weighed powder is often equilibrated to room temperature before opening to avoid condensation on the solid. Working solutions are typically divided into single-use aliquots and frozen rather than stored refrigerated for long periods. Reported shelf lives vary widely between laboratories, and no single set of conditions is universally treated as a reference standard, which complicates direct comparison of published stability figures.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Copper(II)-tripeptide complex | One peptide ligand with one coordinated metal centre |
| Peptide sequence | Gly-His-Lys | Three residues written in one-letter notation |
| Free peptide mass | 340.4 g/mol | Metal-free GHK; the complex has a higher mass |
| Appearance | Blue to violet solid or solution | Colour originates from copper d orbital transitions |
| Storage | Desiccated, -20 °C, protected from light | Dry powder is more stable than dissolved material |
The molecular weight and charge of GHK-Cu depend on the pH and the number of coordinated ligands. At neutral pH, the peptide typically binds one copper ion, but ternary complexes with other biomolecules can form. Spectroscopic methods such as electron paramagnetic resonance and circular dichroism are used to study the coordination environment. Reports on the exact geometry vary because the complex is dynamic in solution. Researchers often use synthetic GHK-Cu rather than extracted material to control stoichiometry and purity.
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.
Purity assessment typically involves high-performance liquid chromatography for the peptide and atomic spectroscopy for copper content. The ratio of copper to peptide is a key quality parameter; a value near one indicates proper stoichiometry. Impurities can include free peptide, copper salts, and truncated sequences from synthesis. Because the complex is dynamic, sample preparation and mobile-phase conditions can shift the observed species. Reported purity values therefore depend on the analytical method and should be interpreted with that context.
Characterizing GHK-Cu requires methods that distinguish the intact complex from free peptide and unbound copper. UV-visible absorption around 600 nm provides a rapid check for copper coordination, while circular dichroism reports on peptide secondary structure. Mass spectrometry confirms the peptide mass and can detect copper adducts under carefully controlled conditions. Electron paramagnetic resonance is particularly informative for Cu(II) because it reveals the ligand field symmetry. No single technique fully defines the complex, so laboratories combine orthogonal methods.
== History == The disease was first described by German neurologist Hans Gerhard Creutzfeldt in 1920 and shortly afterward by Alfons Maria Jakob, giving it the name Creutzfeldt–Jakob disease. Some of the clinical findings described in their first papers do not match current criteria for Creutzfeldt–Jakob disease, and it has been speculated that at least two of the people in the initial studies had a different illness. An early description of familial CJD stems from the German psychiatrist and neurologist Friedrich Meggendorfer (1880–1953). A study published in 1997 counted more than 100 cases worldwide of transmissible CJD and new cases continued to appear at the time. The first report of suspected iatrogenic CJD was published in 1974. Animal experiments showed that corneas of infected animals could transmit CJD, and the causative agent spreads along visual pathways. A second case of CJD associated with a corneal transplant was reported without details. In 1977, CJD transmission caused by silver electrodes previously used in the brain of a person with CJD was first reported. Transmission occurred despite the decontamination of the electrodes with ethanol and formaldehyde. Retrospective studies identified four other cases likely of a similar cause. The rate of transmission from a single contaminated instrument is unknown, although it is not 100%. In some cases, the exposure occurred weeks after the instruments were used on a person with CJD.
Metopon (5-methylhydromorphone, CAS number 124-92-5) is an opioid analogue that is a methylated derivative of hydromorphone which was invented in 1929 as an analgesic. Metopon is sometimes used in medicine. Although longer acting than hydromorphone, metopon is less potent and its oral bioavailability is fairly low. Generally, metopon has few advantages to distinguish it from other, more commonly used opioid analgesics, although it does have a slightly lower tendency to produce nausea and respiratory depression compared to morphine. In Canada, as of 1948, the hydrochloride of metopon (free base conversion ratio 0.891, molecular weight 335.8) was available only for oral administration for malignant pain and for maintenance of those habituated to morphine; the only dosage form available was singly scored 8 mg tablets. It was manufactured by Parke, Davis, & Co., and was only for sale to doctors and hospitals. Parke, Davis & Co. did not sell metopon to pharmacies. It is unknown whether metopon tablets are still manufactured and sold in Canada. Metopon tablets, ampoules, and suppositories are available in Switzerland, Austria, Germany, and other countries in Continental Europe and the drug is used in Patient Controlled Analgesia pumps for severe chronic pain in particular. Metopon is listed under Schedule II of the US Controlled Substances Act 1970, meaning it has an accepted medical use, but at this time it is not produced commercially and is seen only in laboratory research. It did see some use in medicine — oncology in particular — in the US in the 1950s.
Carindacillin (INN), also known as carbenicillin indanyl (USAN), is a penicillin antibiotic. It is a prodrug of carbenicillin. It is administered orally, as the sodium salt. It was formerly marketed in the United States by Pfizer under the brand name Geocillin. Pfizer withdrew Carindacillin from the U.S. market sometime after 2008.
=== March === March 2 A major car crash in Imperial County, California kills 13 people and injures 13 others. COVID-19 pandemic Against CDC warnings, Texas Governor Greg Abbott lifts the statewide mask requirement and allows businesses to open at 100% capacity beginning March 10. Oregon reports its first cases of the Lineage P.1 variant in two people from Douglas County who previously traveled to Brazil. March 5 COVID-19 pandemic Illinois reports its first case of the Lineage P.1 variant first detected in Brazil in a person from Chicago. Tennessee reports its first case of the 501.V2 variant first detected in South Africa. March 6 – The Senate passes the American Rescue Plan Act, President Biden's $1.9 trillion COVID-19 relief package. March 7 – March 2021 Hawaii floods – Floods in Hawaii leave one missing, destroy six homes, force evacuations, and leave 1,300 without electricity. March 8 Missouri Senator Roy Blunt announces he will not run for re-election in 2022. The trial for Derek Chauvin, a former police officer involved in the murder of George Floyd last May, begins with jury selection. COVID-19 pandemic Hawaii reports its first case of South Africa's 501.V2 variant in an Oahu resident with no travel history. Michigan reports its first case of the 501.V2 variant in a child from Jackson County. March 10 COVID-19 pandemic Michigan surpasses 600,000 confirmed cases of COVID-19. New Jersey reports its first case of 501.V2 variant first detected in South Africa.
Sources: en.wikipedia.org
=== Proteins === In the secondary structure of proteins, hydrogen bonds form between the backbone oxygens and amide hydrogens. When the spacing of the amino acid residues participating in a hydrogen bond occurs regularly between positions i and i + 4, an alpha helix is formed. When the spacing is less, between positions i and i + 3, then a 310 helix is formed. When two strands are joined by hydrogen bonds involving alternating residues on each participating strand, a beta sheet is formed. Hydrogen bonds also play a part in forming the tertiary structure of protein through interaction of R-groups. (See also protein folding). Bifurcated H-bond systems are common in alpha-helical transmembrane proteins between the backbone amide C=O of residue i as the H-bond acceptor and two H-bond donors from residue i + 4: the backbone amide N−H and a side-chain hydroxyl or thiol H+. The energy preference of the bifurcated H-bond hydroxyl or thiol system is −14 or 167 kJ/mol (−3.4 or 40 kcal/mol) respectively. This type of bifurcated H-bond provides an intrahelical H-bonding partner for polar side-chains, such as serine, threonine, and cysteine within the hydrophobic membrane environments. The role of hydrogen bonds in protein folding has also been linked to osmolyte-induced protein stabilization. Protective osmolytes, such as trehalose and sorbitol, shift the protein folding equilibrium toward the folded state, in a concentration dependent manner.
The method is the collection of conditions in which the GC operates for a given analysis. Method development is the process of determining what conditions are adequate and/or ideal for the analysis required. Conditions which can be varied to accommodate a required analysis include inlet temperature, detector temperature, column temperature and temperature program, carrier gas and carrier gas flow rates, the column's stationary phase, diameter and length, inlet type and flow rates, sample size and injection technique. Depending on the detector(s) (see below) installed on the GC, there may be a number of detector conditions that can also be varied. Some GCs also include valves which can change the route of sample and carrier flow. The timing of the opening and closing of these valves can be important to method development.
== References == Coe, Sophie D. (1994), America's First Cuisines, ISBN 0-292-71159-X Foster, Nelson. Chilies to Chocolate: Food the Americas Gave the World. The Univ. of Arizona Press. Jacobsen, Sven-Erik. "The Worldwide Potential for Quinoa (Chenopodium quinoa Willd.)." Food Reviews International 19.1-2 (2003): 167-177. Jennings, Justin & Guy Duke, ‘Making the typical exceptional: the elevation of Inca cuisine’, in The Oxford Handbook of the Incas. Eds. Sonia Alconini & R. Alan Covey. New York: Oxford University Press, 2018. Popenoe, Hugh, Steven R. King, Jorge Leon, Luis Sumar Kalinowski, and Noel D. Vietmeyer (1989), Lost Crops of the Incas, ISBN 0-309-04264-X
==== Predictive Low Glucose Suspend (PLGS) ==== A step forward from threshold suspend systems, predictive low glucose suspend (PLGS) systems use a mathematical model to extrapolate predicted future blood sugar levels based on recent past readings from a CGM. This allows the system to reduce or halt insulin delivery prior to a predicted hypoglycemic event.
== Structure and isoforms == The structure of prolactin is similar to that of growth hormone and placental lactogen. The molecule is folded due to the activity of three disulfide bonds. Significant heterogeneity of the molecule has been described, thus bioassays and immunoassays can give different results due to differing glycosylation, phosphorylation and sulfation, as well as degradation. The non-glycosylated form of prolactin is the dominant form that is secreted by the pituitary gland. The three different sizes of prolactin are:
Sources: en.wikipedia.org
It consists of a three-amino-acid peptide, glycine-histidine-lysine, bound to one copper(II) ion. The peptide supplies four nitrogen donor atoms, and the resulting complex is stable in neutral aqueous solution. The metal-free peptide is usually called GHK.
The three letters are the standard one-letter codes for glycine, histidine, and lysine. The suffix -Cu indicates the coordinated copper ion. Cosmetic ingredient lists often use the alternative name copper tripeptide-1 for the same complex.
No. Free GHK is the peptide alone, while GHK-Cu contains a bound copper atom. The two differ in colour, charge, and binding behaviour, so any study that measures copper delivery must state which form was used.
Inductively coupled plasma mass spectrometry or atomic absorption spectroscopy gives total copper after acid digestion. Combining that value with a peptide concentration from chromatography or amino acid analysis yields the metal-to-peptide ratio.