The short version of heptapeptide fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-06-30 and is reviewed periodically as new material appears.
Once dissolved, the peptide is far less stable than the dry powder. Aqueous solutions are subject to hydrolysis, oxidation at susceptible residues and gradual loss of material through adsorption onto glass and plastic surfaces. Terminal glutamine can cyclise under some conditions, producing a related species that complicates purity assessment. Dilute solutions tend to lose a larger fraction of material to surfaces than concentrated ones. Buffers, pH and ionic strength all influence the rate of change, so stability figures are only meaningful when those parameters are stated alongside the storage interval.
Detection in biological samples relies on mass spectrometry, typically liquid chromatography coupled to tandem mass spectrometry after peptide extraction and enrichment. Intact peptides can also be confirmed by high-resolution mass measurement together with fragmentation data. Detection windows in urine are short because the peptide is degraded by proteases and cleared quickly, and concentrations are low. Many jurisdictions treat the compound as a prohibited substance in sport, grouped with peptide hormones and related factors, while it is not an approved therapeutic product. Identity and purity statements therefore rest on certificates of analysis, ideally issued by an independent laboratory.
No major regulatory agency has approved TB-500 for therapeutic use, and it holds no pharmacopoeial monograph. The name appears on the World Anti-Doping Agency prohibited list within the class covering peptide hormones, growth factors, and related substances. Detection in doping control relies on mass spectrometric methods applied to urine, often after preparation steps that concentrate the analyte. Discussion of TB-500 therefore clusters in biochemistry, sports medicine, and anti-doping literature rather than in registered clinical trials.
TB-500 is a synthetic peptide preparation marketed under a name derived from thymosin beta-4, a 43-residue actin-binding protein first isolated from thymus tissue. The full-length protein has a reported molecular mass near 4963 Da, while material sold as TB-500 is often described as a fragment containing the actin-binding motif LKKTETQ. Because suppliers use the name inconsistently, published sources sometimes refer to the same label as a fragment, a synthetic copy, or a related analog. This naming ambiguity complicates direct comparison of reports across studies.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white solid | Lyophilised cake or powder |
| Solubility class | Freely soluble in water | Aqueous buffers also used |
| Typical storage temperature | About -20 degrees Celsius | Dry, sealed and protected from light |
| Typical analytical method | Reversed-phase HPLC or LC-MS/MS | Used for purity, identity and quantification |
| Common synonyms | Thymosin beta-4 fragment | Also listed under fragment-based descriptions |
Interest in the peptide grew during the 2000s and 2010s, when studies of tendon and ligament injuries in horses reported changes in lesion size after treatment. Those reports circulated widely outside the scientific literature and shaped much of the current online discussion. Subsequent reviews noted inconsistent study design, small groups, and a shortage of independent replication. Popular descriptions often blur the line between the fragment, the complete protein, and unrelated growth factors, which complicates comparisons across sources.
TB-500 is a synthetic peptide whose sequence corresponds to a short fragment near the N-terminus of thymosin beta-4, a small protein present in most mammalian cells. The fragment is commonly cited as containing the actin-binding region of the parent molecule, which is why it appears in laboratory work on cell migration and tissue repair. Suppliers distribute it as a lyophilised powder intended for research use. Its identity is defined by amino acid sequence and by the presence of an acetyl group on the N-terminal residue.
Animal work has examined the peptide in models of cardiac injury, skin wounding, and corneal repair, with reported outcomes covering cell migration, inflammatory cell influx, and tissue remodeling. Several of those experiments used the full-length protein or longer fragments instead of the seven-residue sequence, which makes direct comparison between reports difficult. Results are generally described as tissue-dependent, and effect sizes vary considerably across laboratories. Independent replication is uneven, so the overall picture is incomplete rather than settled.
Controlled human trials of the short fragment are scarce. Much of what appears in review articles is extrapolated from animal models or from studies of the parent protein, and literature searches return a larger body of cardiac and ophthalmic work on thymosin beta-4 than on the abbreviated peptide. Regulatory treatment differs by jurisdiction, and in several countries the material is handled as a research chemical rather than an approved therapeutic. Statements about human benefit should be read as provisional.
Biological interest in this peptide centers on its relationship to actin dynamics. Thymosin beta-4 binds monomeric actin through an LKKTET motif, and a short sequence carrying that motif can compete with other actin-binding proteins in cell-free preparations. Investigators propose that such competition shifts the balance between filament assembly and disassembly, which in turn affects how readily a cell extends protrusions and migrates. Most of the supporting observations come from cultured cells and purified protein systems rather than from intact organisms.
Published work involving this sequence spans actin-binding assays, cell-migration studies, wound-healing models, and cardiovascular or musculoskeletal experiments. Much of the biological rationale derives from in vitro systems and animal models, and the number of controlled human studies is small. Reported outcomes vary across preparations, doses, and routes, which complicates comparison between studies. Reviews generally describe the evidence base as preliminary rather than settled. Mechanistic explanations are often proposed by analogy to the parent protein rather than demonstrated directly.
TB-500 is a synthetic seven-amino-acid peptide with the sequence LKKTETQ, corresponding to residues 17 through 23 of the protein thymosin beta-4. The N-terminus is typically acetylated in the described form, giving a monoisotopic mass near 888.5 Da and an average mass of about 889 Da. The designation TB-500 is a catalogue label rather than a formal chemical name, and the same sequence appears in the literature under several alternative abbreviations. It is handled as a research reagent rather than a pharmaceutical product.
Fourier transform infrared spectroscopy (FTIR) is a technique used to obtain an infrared spectrum of absorption or emission of a solid, liquid, or gaseous material. An FTIR spectrometer collects high-resolution spectral data over a wide spectral range, from the near- to far-IR region. This confers a significant advantage over a dispersive spectrometer, which measures intensity over a narrow range of wavelengths at a time. The term Fourier transform infrared spectroscopy originates from the fact that a Fourier transform (a mathematical process) is required to convert the raw data into the actual spectrum.
== Plot == An expedition discovered a derelict alien reconnaissance spaceship, which turned out to be fully automated and run by robots. Doctor Pavlysh, a member of the team, accidentally discovers scattered notes written in Russian. It turns out that these were the diary of a Soviet woman, Nadezhda Matveyevna Sidorova. In 1956, she was abducted by this spaceship, whose mission was to collect biological specimens all over the universe, and she has become a living exhibit on the spaceship. Her diary covers the long second half of her life, hence the title of the novel. Nadezhda, the only human occupant, was able to communicate with other captured intelligent non-humanoid species, whom she calls "trepangs" due to their appearance. Together, they organize an escape from the vessel, but Nadezhda Sidorova tragically dies while distracting the guards, allowing the others to escape. Humans later learned that there is a monument to Nadezhda Sidorova at the native planet of the "trepangs", whose memry is cherished there.
Synthetic organisms may offer increased hazard control because they can be engineered with "intrinsic" biocontainment methods that limit their growth in an uncontained environment, or prevent horizontal gene transfer to natural organisms. Examples of intrinsic biocontainment include auxotrophy, biological kill switches, inability of the organism to replicate or to pass modified or synthetic genes to offspring, and the use of xenobiological organisms using alternative biochemistry, for example using artificial xeno nucleic acids (XNA) instead of DNA.
Imino acids are structurally related to amino acids, which have amino group instead of imine—a difference of single vs double-bond between nitrogen and carbon. The simplest example is dehydroglycine. D-Amino acid oxidase is an enzyme that is able to convert amino acids into imino acids. Also the direct biosynthetic precursor to the amino acid proline is the imino acid (S)-Δ1-pyrroline-5-carboxylate (P5C).
== Education == Lee received a B.A. degree in chemistry from the University of Utah in 1971 and a Ph.D. in analytical chemistry from Indiana University Bloomington in 1975, after which he spent one year (1975–76) at the Massachusetts Institute of Technology as a postdoctoral research associate. Upon leaving MIT, he accepted a faculty position in the Chemistry Department at Brigham Young University, where he is the H. Tracy Hall Professor of Chemistry.
Sources: en.wikipedia.org
The Davy lamp could also detect high levels of blackdamp (which sinks, and collects near the floor) by burning less brightly, while methane, another suffocating gas and explosion risk, would make the lamp burn more brightly. In February 2020, three people died from suffocation at a party in Moscow when dry ice (frozen CO2) was added to a swimming pool to cool it down. A similar accident occurred in 2018 when a woman died from CO2 fumes emanating from the large amount of dry ice she was transporting in her car.
Medical-grade disposable hypodermic syringes are often used in research laboratories for convenience and low cost. Another application is to use the needle tip to add liquids to very confined spaces, such as washing out some scientific apparatus. They are often used for measuring and transferring solvents and reagents where a high precision is not required. Alternatively, microliter syringes can be used to measure and dose chemicals very precisely by using a small diameter capillary as the syringe barrel. The polyethylene construction of these disposable syringes usually makes them rather chemically resistant. There is, however, a risk of the contents of the syringes leaching plasticizers from the syringe material. Non-disposable glass syringes may be preferred where this is a problem. Glass syringes may also be preferred where a very high degree of precision is important (i.e. quantitative chemical analysis), because their engineering tolerances are lower and the plungers move more smoothly. In these applications, the transfer of pathogens is usually not an issue. Used with a long needle or cannula, syringes are also useful for transferring fluids through rubber septa when atmospheric oxygen or moisture are being excluded. Examples include the transfer of air-sensitive or pyrophoric reagents such as phenylmagnesium bromide and n-butyllithium respectively. Glass syringes are also used to inject small samples for gas chromatography (1 μl) and mass spectrometry (10 μl). Syringe drivers may be used with the syringe as well.
A comprehensive list of copper alloy surface products that have been granted antimicrobial registration status with public health claims by the EPA can be found here: Antimicrobial copper-alloy touch surfaces#Approved products. Clinical trials are currently being conducted on microbial strains unique to individual healthcare facilities worldwide to evaluate to what extent copper alloys can reduce the incidence of infection in hospital environments. Early results disclosed in 2011 from clinical studies funded by the U.S. Department of Defense that are taking place at intensive care units (ICUs) at Memorial Sloan-Kettering Cancer Center in New York City, the Medical University of South Carolina, and the Ralph H. Johnson VA Medical Center in Charleston, South Carolina, indicate that rooms where common touch surfaces were replaced with copper demonstrated a 97% reduction in surface pathogens versus the non-coppered rooms and that patients in the coppered ICU rooms had a 40.4% lower risk of contracting a hospital acquired infection versus patients in non-coppered ICU rooms.
=== Australia === In-N-Out Burger has also had other similarly named imitators in Australia that confuse consumers into thinking that the businesses is associated with the Californian-based chain. The company would take the imitators to court for trademark infringement and has opened one-day pop-ups in Sydney in 2012, 2013, 2016, 2017, 2019, and 2022; Brisbane in 2020; Melbourne in 2014 and 2018; and Perth in 2018 and 2022 to preserve their trademark rights. Customers may wait for several hours before the doors open, but the food would run out very quickly, sometimes in less than hour after opening. Although In-N-Out may not have plans to open a permanent location outside its current operating region, the business strategy of having one-day pop-ups is to maintain a business presence in the country under Australian trademark law without opening a permanent restaurant. In-N-Out successfully defended their trademarks and intellectual property rights in Australia in 2020 against Hashtag Burgers Pty Ltd, formerly doing business as "Funk N Burgers" and "Down-N-Out Burger". In 2021, In-N-Out filed a lawsuit against Queensland-based Rich Asians Pty Ltd doing business as "In & Out Aussie Burgers".
As well as basic pay, most awards set rates for working overtime, extra pay for work on Sundays or public holidays, and superannuation. For all breaches of modern awards, there are civil remedies. Under FWA 2009 section 323 requires that people are paid in money, rather than in kind (or "truck"). For example, in Australian Education Union v Victoria it was held to be unlawful for the state government to deduct each fortnight between $4 and $17 from salaries of teachers who had been given laptops. Superannuation in Australia provides people with workplace pensions in retirement, and employers must pay a "superannuation guarantee" of 12% of income from 2025 to approved funds. There may also be no unauthorised deductions of wages, and there is a right to be paid at least monthly. Under the Superannuation Industry (Supervision) Act 1993 section 89, the "basic representation rule" is that boards of funds have an equal number of member and employer-appointed trustees, but there may also be "independent" trustees or directors appointed by the incumbent board. By 2023, there were $3.5 trillion in assets under management at Australian superfunds, however the voting rights on corporation shares, which are usually held by super funds, are typically outsourced to asset managers who are not yet bound to any consistent voting policy that reflects the interests of the workforce.
Sources: en.wikipedia.org
== Story == Medea is centered on Medea's calculated desire for revenge against her unfaithful husband. Medea is of divine descent and has the gift of prophecy. She married Jason and used her magic powers and advice to help him find and retrieve the golden fleece. The play is set in Corinth some time after Jason's quest for the Golden Fleece, where he met Medea. The play begins with Medea in a blind rage towards Jason for arranging to marry Glauce, the daughter of king Creon. The nurse, overhearing Medea's grief, fears what she might do to herself or her children. Creon, in anticipation of Medea's wrath, arrives and reveals his plans to send her into exile. Crouching at Creon's feet, Medea begs him in the name of her children to allow her one day's delay. At this Creon is moved and grants to her one more day in Corinth. Medea's unexpected power of persuasion or even of fascination lies in her change of attitude: instead of preaching to Creon about the unpopularity of the sophoi she plays the role of a desperate mother, needing one day to prepare for exile. Medea is aware of the humiliating quality of this tactic, but she justifies it on the grounds of a gain and of her need to remain in Corinth: "Do you think that I would ever have flattered that man unless I had some gain to make or some device to execute? I wouldn't have even spoken or touched him with my hands". In the next scene Jason arrives to explain his rationale for his apparent betrayal.
== List legend == Each group of radionuclides, starting with the longest-lived primordial radionuclides, is sorted by decreasing half-life, but the tables are sortable by other columns. All columns sort by usual lexicographical order; in the case of the nuclide column this gives order on the mass number A.
=== Genes in other plants === CLE genes have been found in numerous monocots, dicots, and even moss. Research has even shown that some plants, like rice, contain the presence of a multi-CLE domain. Various CLE-like genes have also been found in the genomes of plant-parasitic nematodes such as beet, soybean and potato cyst nematodes.
It was remarkable, how, after the war, this rather unassuming scientist who had spent a lifetime in the laboratory, became an effective administrator and an important public figure in Germany. Hahn, famous as the discoverer of nuclear fission, was respected and trusted for his human qualities, simplicity of manner, transparent honesty, common sense and loyalty.
Sources: en.wikipedia.org
Sealed, dry and protected from light at reduced temperature is the usual laboratory convention. Allowing a cold vial to reach room temperature before opening limits condensation. Repeated opening exposes the powder to moisture and should be minimised.
Reported purity reflects the batch tested, the chromatographic method used and whether an independent laboratory performed the work. Values quoted without method detail or a traceable certificate are difficult to compare directly.
Short peptides are rapidly broken down by proteases and appear at low concentrations in urine, so the detection window is narrow. Sensitive extraction combined with tandem mass spectrometry is typically required.
Not necessarily. TB-500 is a commercial label that suppliers apply to synthetic peptides described as thymosin beta-4 or a fragment of it. Published research most often studies the full-length protein, so statements about one do not automatically transfer to the other.