Everything below concerns stoichiometric ratio. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2025-12-19. Numbers and descriptions here follow the published literature rather than marketing material.
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.
GHK-Cu is the copper-binding complex formed by the tripeptide glycyl-L-histidyl-L-lysine and a copper(II) ion. The free peptide is usually written as GHK, and the complex is written as GHK-Cu or Cu-GHK. The sequence was identified in human plasma and later detected in saliva and urine. Its name comes from the single-letter codes of glycine, histidine and lysine. The complex is widely described as a naturally occurring carrier of copper in blood rather than as a free peptide with its own hormonal role.
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.
| Property | Value | Notes |
|---|---|---|
| Copper binding sites | Imidazole, amino, and amide nitrogens | Form chelate rings with Cu(II) |
| Conditional binding constant | Reported near 10^16 at neutral pH | Value depends on method and medium |
| Visible absorption | Broad band in the blue-violet region | Source of the characteristic color |
| Common analytical methods | LC-MS, HPLC, UV-Vis, ICP-OES | Used for identity and copper content |
| Main degradation routes | Oxidation, photolysis, hydrolysis | Accelerated by light, heat, and pH extremes |
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.
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.
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.
Identity and purity are established with a combination of chromatographic and spectroscopic techniques. Reversed-phase high-performance liquid chromatography separates the intact complex from peptide fragments and free copper, and the elution profile yields a purity estimate. Mass spectrometry gives the mass of the intact species and exposes degradation products. Ultraviolet-visible spectroscopy displays a broad absorption band in the visible region that is characteristic of the copper center. Nuclear magnetic resonance is less informative here, because the paramagnetic metal broadens signals and complicates spectral interpretation.
Copper content is measured separately, since a peptide assay alone does not report the metal-to-peptide ratio. Elemental techniques such as inductively coupled plasma optical emission spectroscopy quantify copper after acid digestion of the sample. The result is compared with the theoretical value for a one-to-one complex, and a shortfall indicates free peptide or partial dissociation. Suppliers differ in how they state purity, as some quote peptide content and others quote the whole complex. A defined stoichiometry therefore requires both a peptide assay and a copper assay.
Gewinnt der Spieler, der das Break hinnehmen musste, das folgende Aufschlagspiel seines Gegners, so wird dies als Rebreak bezeichnet. Entscheidende Punkte werden als Breakball (falls der Gewinn zu einem Break führt), Satzball oder Matchball bezeichnet. Ein zu Null gewonnener Satz wird englisch als Bagel bezeichnet, was auf die Form dieses Gebäcks verweist. Im Tennisjargon wird ein zu Null verlorener Satz auch als „Höchststrafe“ bezeichnet. Ein ohne Verlustpunkt gespielter Satz (6:0, jeweils nach Spielgewinnen zu 0, demnach 24 in Folge gewonnene Punkte) wird als Golden Set bezeichnet. Wer ein Match 0:6 0:6 verliert, hat im Tennis-Jargon eine Brille verpasst bekommen, oder englisch Double Bagel, drei solche Sätze sind ein Triple Bagel. Ein Satz der 6:1 endet, wird englisch Breadstick genannt, wobei die „Eins“ an die gerade Form eines Grissino erinnern soll (in der italienischen Küche als eine knapp fingerdicke, mürbe Brotstange aus Hefeteig bekannt). Breadstick (wörtlich: Brotstange) ist die englische Bezeichnung für ein Grissino. Im Englischen wird die „Eins“ ohne Aufwärtstrich, also „I“ statt „1“ geschrieben.
In den Verbänden des DTB wird in Verbandsspielen (Damen und Herren), ebenso bei den Senioren und im Doppel häufig kein dritter Satz, sondern ersatzweise ein sogenannter Match-Tie-Break auf zehn Punkte (alternativ: sieben Punkte) gespielt. Ein Match-Tie-Break wird auch bei den US Open und seit 2007 bei den Australian Open im dritten Satz des Mixed-Wettbewerbs gespielt. Bei den French Open, dem Davis Cup und bei den Olympischen Spielen wird im entscheidenden Satz kein Tie-Break gespielt, sondern ein Match-Tie-Break. No-Ad- (kurz für „no advantage“) bzw. Deciding-Point-Regel: Sie kommt seit 2006 vor allem in Doppelkonkurrenzen zum Einsatz und dient der Abkürzung der Aufschlagspiele: Bei Erreichen des Spielstands 40:40 entscheidet der nächste Punkt, der Deciding Point, über den Gewinn. Es ist dann also nicht wie sonst üblich ein Vorsprung von zwei Punkten zum Gewinn nötig. Eine weitere Besonderheit ist, dass die returnierende Partei beim Deciding Point die Wahl hat, von welcher Seite der Aufschläger serviert; vom Schiedsrichter wird dies auch mit „Deciding point, receiver’s choice“ angekündigt. Im Mixed gibt es kein „receiver’s choice“. Hier serviert immer Mann auf Mann und Frau auf Frau. Fast4 Tennis ist ein Format, das 2014 von Tennis Australia initiiert wurde und von den traditionellen Tennisregeln abweichende Regeln zu kürzeren Tennisspielen führen.
Spiele im Einzel werden mit Best-of-Three (zwei Gewinnsätze) oder Best-of-Five (drei Gewinnsätze), kurzen Sätzen (erste 4 gewonnene Spiele) mit einem kurzen Tie-Break bei 3:3 (erste 5 Punkte; sudden death, wenn beide 4 Punkte erreicht haben) gespielt. Außerhalb der WT Regeln:
Sources: de.wikipedia.org
Der Ultimate Tennis Showdown (UTS) ist eine 2020 gegründete internationale Einzel-Tennisliga. Sie verwendet ein modifiziertes Wertungsformat, bei dem das Match in vier Viertel unterteilt wird. Jedes Viertel dauert dabei acht Minuten, nach acht Minuten werden Entscheidungspunkte ausgespielt. Um zu gewinnen, muss ein Spieler drei der vier Viertel für sich entscheiden. Beim Tie Break Tens gibt es weder Spiele noch Sätze, sondern nur ein Match-Tie-Break.
Sources: de.wikipedia.org
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.
Reversed-phase high-performance liquid chromatography and mass spectrometry are common for the peptide portion. Copper content is usually determined by inductively coupled plasma techniques or by spectrophotometry. Ultraviolet-visible spectroscopy takes advantage of the visible absorption band of the copper complex.
Light, oxygen, and elevated temperature promote degradation of the peptide, and strongly acidic or alkaline conditions accelerate hydrolysis. The copper complex is generally more resistant to oxidation than the free peptide. Storage in a dry, dark, cold environment limits loss over time.
The letters GHK are the one-letter codes for glycine, histidine and lysine, the three amino acids in the peptide. The suffix Cu indicates that the peptide is bound to a copper ion, normally copper(II).