If you have been reading about glycyl-histidyl-lysine 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 2026-05-17. Numbers and descriptions here follow the published literature rather than marketing material.
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.
GHK-Cu is a coordination complex formed between the tripeptide glycyl-L-histidyl-L-lysine and a copper(II) ion. The peptide backbone consists of glycine, histidine, and lysine joined in that order. Copper is held through the imidazole nitrogen of histidine and the alpha-amino group at the N-terminus, which together produce a square-planar arrangement around the metal center. The solid appears blue to violet, a color that originates from d-d electronic transitions within the copper coordination sphere. The complex is indexed under CAS number 89030-95-5.
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.
| 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 |
GHK-Cu is a coordination complex formed between the tripeptide glycyl-L-histidyl-lysine and a copper(II) ion. The peptide sequence is conventionally written as Gly-His-Lys, abbreviated GHK. Copper binds through the imidazole nitrogen of histidine, the alpha-amino group, and a deprotonated amide nitrogen, producing a square-planar geometry. The complex carries a net positive charge near physiological pH and is intensely blue in aqueous solution. The metal-free peptide is often written simply as GHK, while the copper-bound form is written GHK-Cu.
The compound was first isolated from human plasma by the biochemist Loren Pickart in 1973. Early work identified it as a factor that altered the behavior of cultured liver cells, and later studies linked it to connective tissue and wound-related processes. Reported plasma concentrations fall markedly between roughly age twenty and age sixty, a pattern that generated interest in copper peptide biology. Whether that decline has functional consequences remains an open question, because differences observed across age groups do not by themselves establish causation. Research interest later expanded into cosmetic and tissue-culture settings.
Mechanistic accounts focus on how the complex delivers copper and how the released peptide interacts with the extracellular matrix. Copper is an essential cofactor for lysyl oxidase and other enzymes involved in collagen and elastin cross-linking, and GHK is one of several peptides able to carry the metal. Reported effects include altered gene expression in fibroblasts and changes in matrix metalloproteinase activity, although many of these findings come from cell culture rather than whole organisms. The relative contribution of the peptide backbone, the copper ion, and downstream copper metabolism is not fully resolved.
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.
Handling practices for the solid material emphasise low temperature and dryness. The lyophilised or powdered form is typically kept at refrigerator or freezer temperatures together with a desiccant. Working solutions are often prepared fresh, because repeated freeze-thaw cycles and extended storage may alter the complex. Glass or inert plastic containers are preferred over materials that could leach metal ions into the preparation. Such practices follow general peptide conventions rather than substance-specific regulations.
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.
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.
The peptide was first isolated from human albumin in 1973 by Loren Pickart, who later described its copper-binding behavior. Early work linked the complex to wound healing and tissue remodeling. Plasma levels of GHK decline with age, a pattern that stimulated interest in topical and supplemental applications. Researchers have reported that the tripeptide influences collagen synthesis, antioxidant defense, and inflammatory signaling in cell and animal models. Human clinical evidence remains limited and often relies on small studies.
=== Military legacy === The war was the harbinger of a new type of combat: guerrilla warfare. The counterinsurgency techniques and lessons learned (restriction of movement, containment of space, targeting of anything that could give sustenance to guerrillas, harassment through sweeper groups coupled with rapid reaction forces, sourcing and co-ordination of intelligence, and nurturing of native allies) were used by the British, and other forces, in future guerrilla campaigns including to counter Malayan communist rebels during the Malayan Emergency. In World War II the British adopted concepts of raiding from the Boer commandos when they set up special raiding forces, and in acknowledgement chose the name British Commandos.
=== Predicting IDPs by sequence === Separating disordered from ordered proteins is essential for disorder prediction. One of the first steps to find a factor that distinguishes IDPs from non-IDPs is to specify biases within the amino acid composition. The following hydrophilic, charged amino acids A, R, G, Q, S, P, E and K have been characterized as disorder-promoting amino acids, while order-promoting amino acids W, C, F, I, Y, V, L, and N are hydrophobic and uncharged. The remaining amino acids H, M, T and D are ambiguous, found in both ordered and unstructured regions. A more recent analysis ranked amino acids by their propensity to form disordered regions as follows (order promoting to disorder promoting): W, F, Y, I, M, L, V, N, C, T, A, G, R, D, H, Q, K, S, E, P. As it can be seen from the list, small, charged, hydrophilic residues often promote disorder, while large and hydrophobic residues promote order. This information is the basis of most sequence-based predictors. Regions with little to no secondary structure, also known as NORS (no regular secondary structure) regions, and low-complexity regions can easily be detected. However, not all disordered proteins contain such low complexity sequences.
=== College of Nurses of Ontario === Wettlaufer was charged with professional misconduct by a disciplinary panel convened by College of Nurses of Ontario on July 25, 2017. Even though she had already been found guilty in a criminal trial and voluntarily surrendered her nursing license, the formal hearing was required by College to officially bar her from the profession. Wettlaufer declined to participate in the hearing and was found guilty based on court documents from her criminal trial as well as her previous confession. Her conduct was deemed "disgraceful and dishonourable" by the disciplinary panel and her nursing registration was formally revoked indefinitely, barring her from ever practising nursing in Ontario again. The chair of the five-person disciplinary panel that heard Wettlaufer's case said it was "the most egregious and disgraceful conduct this panel has ever considered".
Sources: en.wikipedia.org
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In 1985, the FDA further required a boxed warning to be added, but the problem grew with an estimated 1000 birth defects attributed to the drug by early 1988. While an advisory committee of pediatricians and Centers for Disease Control and Prevention (CDC) staff advised the FDA to restrict Accutane prescriptions, the FDA instead required Roche to expand its warnings of potential side effects and provide informed consent forms to doctors. In 2000, the CDC reported that Roche's Pregnancy Prevention Program of providing contraception counseling and pregnancy testing for women prescribed Accutane was ineffective. The revamped "Targeted Pregnancy Prevention Program" advised women to use two kinds of contraceptives and two pregnancy tests while requiring doctors to directly provide prescriptions to pharmacists to limit off-label use. After Representative Bart Stupak's son committed suicide while taking Accutane in May 2000, Congress held hearings in which some dermatologists attested to Accutane's efficacy in reducing acne and its associated stigma, while others petitioned the FDA for further restrictions of its use. In 2001, the FDA announced the System to Manage Accutane Related Teratogenicity (SMART), which required Roche to train doctors for a sticker-based system of verifying that female patients took pregnancy tests before using Accutane. SMART was replaced by the iPLEDGE program in March 2006. In February 2002, Roche's patents for isotretinoin expired, allowing generic drugs to enter the market.
== Neuroendocrine tumors (209–209) == 209 Neuroendocrine tumors 209.0 Malignant carcinoid tumors of the small intestine 209.1 Malignant carcinoid tumors of the appendix, large intestine, and rectum 209.2 Malignant carcinoid tumors of other and unspecified sites 209.3 Malignant poorly differentiated neuroendocrine carcinoma 209.4 Benign carcinoid tumors of the small intestine 209.5 Benign carcinoid tumors of the appendix, large intestine, and rectum 209.6 Benign carcinoid tumors of other and unspecified sites
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.
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.