This is a working overview of GHK-Cu, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2025-07-29. Anything still debated is marked as such rather than presented as settled.
The sequence carries three residues in the order glycine, histidine, lysine, which places a small, flexible chain around a single metal centre. Compared with larger copper-binding proteins, the complex is compact and its coordination chemistry can be reproduced with synthetic peptide in a laboratory. Published structural work agrees on the nitrogen donor set but differs in the exact geometry assigned under some conditions, so the arrangement is best treated as well characterised in outline rather than fixed in every detail.
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.
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.
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.
| 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 |
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.
Copper takes part in redox chemistry, and the same property that makes it useful in enzymes can generate reactive oxygen species when the ion is loosely bound. GHK chelates copper through imidazole, amino, and amide nitrogen donors, which reduces the amount of free copper in solution. Whether that chelation is protective, neutral, or harmful in a given tissue is not settled. Laboratory assays report both antioxidant and pro-oxidant behavior, depending on the conditions and the readout used.
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.
Solid material is typically kept as a lyophilised powder in a sealed, light-protected container at minus 20 degrees Celsius, with desiccant where humidity is high. Working solutions are often prepared fresh, aliquoted and frozen to avoid repeated freeze-thaw cycles. Glassware and buffers are checked for trace metal contamination, since other transition metals can displace copper. Records of lot number, reconstitution date and storage temperature help trace unexpected colour changes. Blue colour itself is not a reliable purity test, because partly degraded solutions can remain visibly coloured.
Identity and purity are normally checked by reversed-phase high-performance liquid chromatography, often coupled to mass spectrometry. The peptide absorbs in the ultraviolet region, and the copper complex also shows a broad visible absorption band that can be followed spectroscopically. Copper content is measured separately, for example by inductively coupled plasma mass spectrometry or atomic absorption spectroscopy, because the peptide assay alone does not confirm how much metal is bound. Purity figures therefore need a stated basis: peptide peak area, copper content, or both.
Aqueous GHK-Cu solutions are less stable than the dry powder. Light, dissolved oxygen and elevated temperature all accelerate loss of the intact complex, and the main observable changes are fading of the blue colour and the appearance of peptide fragments. Acidic conditions protonate the histidine imidazole and weaken copper binding, while strongly alkaline conditions promote hydrolysis of the peptide backbone. Because several degradation routes operate at once, a single shelf-life figure does not describe all storage conditions.
Nuclear emulsions are similar to photographic emulsions, except that they are used in particle physics to detect high-energy elementary particles. Whilst an emulsion roughly corresponds to a mixture of at least two immiscible liquids mixed together, by contrast emulsification is the process of dispersing two or more immiscible liquids together through the use of an emulsifier (e.g., lecithin in a mixture of oil and water). Nanoemulsification is the process of emulsification in the nanoscale. A nanoemulsion is a particular kind of emulsion, with droplet sizes on the order of 100 nm.
The electric charge per mole of elementary charges is a constant called the Faraday constant, F, whose value had been essentially known since 1834 when Michael Faraday published his works on electrolysis. In 1910, Robert Millikan obtained the first measurement of the charge on an electron, −e. The quotient F/e provided an estimate of the Avogadro constant. The classic experiment is that of Bower and Davis at NIST, and relies on dissolving silver metal away from the anode of an electrolysis cell, while passing a constant electric current I for a known time t. If m is the mass of silver lost from the anode and Ar the atomic weight of silver, then the Faraday constant is given by:
) is a pharmacokinetic parameter representing the efficiency of drug elimination. This is the rate of elimination of a substance divided by its concentration. The parameter also indicates the theoretical volume of plasma from which a substance would be completely removed per unit time. Usually, clearance is measured in L/h or mL/min. Excretion, on the other hand, is a measurement of the amount of a substance removed from the body per unit time (e.g., mg/min, μg/min, etc.). While clearance and excretion of a substance are related, they are not the same thing. The concept of clearance was described by Thomas Addis, a graduate of the University of Edinburgh Medical School. Substances in the body can be cleared by various organs, including the kidneys, liver, lungs, etc. Thus, total body clearance is equal to the sum clearance of the substance by each organ (e.g., renal clearance + hepatic clearance + pulmonary clearance = total body clearance). For many drugs, however, clearance is solely a function of renal excretion. In these cases, clearance is almost synonymous with renal clearance or renal plasma clearance. Each substance has a specific clearance that depends on how the substance is handled by the nephron. Clearance is a function of 1) glomerular filtration, 2) secretion from the peritubular capillaries to the nephron, and 3) reabsorption from the nephron back to the peritubular capillaries.
== History == myo-Inositol was first isolated from muscle extracts by Johanes Joseph Scherer (1814–1869) in 1850. It was formerly called meso-inositol to distinguish it from the chiro- isomers. However, since all other isomers are meso (non-chiral) compounds, the name myo-inositol is now preferred (myo- being a medical prefix for "muscle"). Inositol was once considered a member of the vitamin B complex, namely vitamin B8 before the discovery that it is made naturally in the human body, and therefore cannot be a vitamin or essential nutrient.
Sources: en.wikipedia.org
Exercise intolerance, Abnormal muscle fatigue (premature fatigue and/or inability to get into second wind), muscle pain (myalgia), cramping or muscle stiffness during and/or after exercise, Shortness of breath (dyspnea), or rapid breathing (tachypnea), or heavy breathing (hyperpnea), or both (exercise hyperventilation) Inappropriate rapid heart rate in response to exercise (tachycardia), Exaggerated cardiorespiratory (breath and heart rate combined) response to exercise (dyspnea/tachypnea/hyperpnea and tachycardia), Exercise-induced myogenic hyperuricemia (exercise-induced accelerated breakdown of purine nucleotides in muscle via adenylate kinase reaction and purine nucleotide cycle), Transient muscle contracture or pseudomyotonia (like a really bad cramp that can last for hours, which is myogenic and EMG silent), May have progressive muscle weakness, May have a pseudoathletic appearance (hypertrophy or pseudohypertrophy) especially of the calves, Reddish-brown urine (myoglobinuria) and considerable breakdown of muscle tissue (rhabdomyolysis). The degree of symptoms varies greatly from person to person and is dependent on the severity of enzymatic or transport protein defect. In extreme cases it can lead to rhabdomyolysis. The symptoms experienced also depend on which metabolic pathway is impaired, as different metabolic pathways produce ATP at different time periods during activity and rest, as well as the type of activity (anaerobic or aerobic) and its intensity (level of ATP consumption).
==== Crusader period ==== The Crusaders renamed the city Ibelin and built its castle there in 1141. An excavation led by Professor Dan Bahat in 2005 revealed the main gate. Its namesake noble family, the House of Ibelin, was important in the Kingdom of Jerusalem and later in the Kingdom of Cyprus. Salvage excavations at the west of the tell unearthed a stash of 53 Crusader coins of the 12th and 13th centuries.
Like perlite, vermiculite is a mineral that has been superheated until it has expanded into light pebbles. Vermiculite holds more water than perlite and has a natural "wicking" property that can draw water and nutrients in a passive hydroponic system. If too much water and not enough air surrounds the plants roots, it is possible to gradually lower the medium's water-retention capability by mixing in increasing quantities of perlite.
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.
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.