If you have been reading about counter-ion 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.
Last reviewed on 2025-08-16. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Purity and identity are separate measurements and are often confused. Reverse-phase high-performance liquid chromatography, usually with ultraviolet detection near 214 nanometres, reports the share of total peak area belonging to the target compound. Mass spectrometry by electrospray or matrix-assisted laser desorption then checks whether the observed mass matches the expected sequence. Neither measurement alone shows that a vial holds the intended peptide. Peptide content, meaning the fraction of vial mass that is genuine peptide rather than counter-ion, water or residual acid, is reported separately and is frequently lower than the stated purity figure.
The regulatory position is broadly consistent across major jurisdictions: no thymosin beta-4 fragment is an approved medicine, and laboratory material is commonly labelled as not intended for human consumption. Anti-doping rules in sport list thymosin beta-4 and its fragments among prohibited peptide hormones. Because these products travel through research-chemical channels rather than pharmaceutical supply chains, quality varies considerably between vendors. Independent testing of identity, purity and sterility is the only dependable check, and a certificate of analysis describes one batch rather than a supplier's whole catalogue.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C38H68N10O14 | Acetylated heptapeptide form |
| Monoisotopic mass | 888.5 Da | Average mass about 889 Da |
| Appearance | White to off-white solid | Usually supplied as lyophilised powder |
| Solubility class | Highly water soluble | Also dissolves in aqueous buffers |
| Common synonyms | Tbeta4 fragment, thymosin beta-4 (17-23) | Refer to the same sequence |
Lyophilised peptide powders are hygroscopic, and the fragment absorbs atmospheric moisture when a vial is opened at room temperature. Weighing and aliquoting are normally done quickly in a dry environment, and stock solutions are divided into single-use portions before freezing. Repeated freeze-thaw cycles are avoided because they promote aggregation and can shift the measured content of a vial. These practices are general to synthetic peptides rather than unique to this sequence, but they matter more for short chains kept for long periods.
The seven-residue chain carries several polar and charged side chains, so it dissolves readily in water and in aqueous buffers near neutral pH. No cysteine is present, so disulphide formation is not a concern and reducing agents are unnecessary. Dilute ammonium hydroxide or acetonitrile-water mixtures are sometimes used for stock solutions when initial dissolution is slow. Strongly alkaline conditions and prolonged contact with oxidising agents are avoided because they can modify lysine-containing stretches, and haze in solution usually signals incomplete dissolution or aggregated material.
Thymosin beta-4 contains 43 amino acids and has a reported molecular mass near 4963 Da. The short fragment most often associated with the TB-500 label, an acetylated chain beginning LKKTETQ, has a reported mass near 889 Da, so the two are easily separated in analytical work. Mass spectrometry and amino acid analysis can confirm which material is present in a given sample. Statements treating TB-500 and thymosin beta-4 as interchangeable are therefore imprecise, even though the two appear together in much of the same literature.
Interest in the compound comes largely from studies of the parent protein, which participates in actin sequestration, cell migration and tissue repair processes. Whether a short fragment reproduces those activities is a separate question that remains open in the published record. Many summaries describe mechanisms by analogy to thymosin beta-4 rather than from direct measurements on the fragment. Claims about activity should be treated as provisional unless a cited study specifies the exact peptide, its purity and the assay used.
TB-500 is a laboratory label applied to a short synthetic peptide that is widely described as a fragment of thymosin beta-4, an actin-binding protein present in most mammalian cells. Suppliers and review articles usually present TB-500 as the N-terminal region of that protein, but the exact sequence attached to the name is not consistent across sources. Some product descriptions list a seven-residue chain; others use the label loosely for the parent protein itself. Because of that variation, any technical discussion of TB-500 needs to state which sequence is meant.
Identity and purity are normally assessed with reversed-phase high-performance liquid chromatography, paired with mass spectrometry to confirm molecular mass. A certificate of analysis reports a purity percentage, usually derived from chromatographic peak area, but that figure does not by itself prove a correct sequence or the absence of counterions. Independent verification may include amino acid analysis or peptide mapping. Batch-to-batch variation is a documented concern in the research chemical market, and the gap between a quoted purity value and actual peptide content can be substantial when the material is a salt or retains residual water.
Lyophilized peptide arrives as a dry cake that should stay sealed until use. Reconstitution is generally performed with sterile water or a buffered solution, and the resulting liquid should be handled gently to limit mechanical stress. Repeated freeze-thaw cycles are widely described as harmful to short peptides, so dividing a reconstituted batch into single-use portions is a common practice. Laboratories also record the solvent, concentration, and date of preparation on the vial label to keep later measurements traceable.
Dry powder is commonly held at minus twenty degrees Celsius, with some suppliers recommending lower temperatures for long-term archival storage. Once dissolved, solutions are typically kept cold and protected from light, since aqueous peptide solutions can lose integrity through hydrolysis or oxidation over time. Stability data specific to this fragment are limited in the public literature, and much of the guidance comes from general peptide handling practice rather than from controlled degradation studies. Users therefore treat stated shelf lives as approximate rather than fixed.
Regulatory status differs by country, but TB-500 is not an approved pharmaceutical in major jurisdictions. It is commonly sold as a research chemical for laboratory use, which places responsibility for identity and purity on the supplier and the laboratory. Published human data are limited, and most reports involve preclinical models or cell culture. Questions about whether the fragment mimics all actions of thymosin beta-4, and under which conditions, remain open. Independent verification of any material is therefore a practical requirement in research settings.
TB-500 is a synthetic heptapeptide with the sequence Ac-LKKTETQ. It corresponds to a short N-terminal region of thymosin beta-4, a 43-amino-acid protein found in many cell types. The fragment contains an actin-binding motif, which is one reason it appears in laboratory studies of cell migration and cytoskeletal dynamics. TB-500 is not the full-length protein and is produced as a research chemical rather than an approved therapeutic agent. Its molecular weight is approximately 889 Da.
=== Singles/EPs/demos === "Children Break" (1988) Barging Into the Presence of God EP (September 1989) UK Indie No. 3 UK No. 135 Half-Life EP (October 1990), 12" contains a bonus spoken-word track "Colour of the Sky" UK No. 86 "Kinky Love" (1991) (12" issued as Flesh Balloon EP) (June 1991) UK No. 72 "Porpoise" (1991) "Throwing Back the Apple" (May 1992) UK No. 93 Fine Friend EP (August 1994) "Fine Friend" (1994), US promo including "One Blue Hill" live acoustic @ KCRW "Angel (Will You Be My)" (1995), US promo
Animals, not humans, serve as reservoir species for rabies and are responsible for passing the virus to humans in the overwhelming majority of cases. Therefore to eliminate rabies in an area is to eliminate rabies from the local animal populations, both wild and domestic. Pre-exposure immunization has been used on domesticated and wild populations. In many jurisdictions, domestic dogs, cats, ferrets, and rabbits are required to be vaccinated.
==== Opium ==== Liu reportedly called opium cultivation the "lifeline" of the 24th Army and derived much of his income from the drug, which was traded and later cultivated on a massive scale. The opium business became extremely profitable after 1936 when the central government started aggressively suppressing production within the Sichuan basin, making opium grown by the Yi in the Xikang highlands extremely profitable. Lawson went as far as to conclude that the Kuomintang's anti-opium campaign was arguably "another form of assistance that the national government granted Liu Wenhui". A similar period of suppression in the lowlands coinciding with an opium boom in the highlands was also documented from 1906 to 1911 under the Qing dynasty. Cultivation of opium in Kham began after 1936, spreading to Liu's territories around the early 1940s. Liu Wenhui profited greatly from this illegal trade, and was able to fund his military and economic projects through opium sales. In 1940, he was alleged to have struck a deal with the Yunnanese governor Long Yun that let tariffed opium from Yunnan pass through Xikang en route to Sichuan. Later, this trade would decline as Xikang became a major opium producer in its own right. Historians including Lawson have so far been unable to place an exact amount on the income that Xikang gained from opium; only that it was probably at least as much as the subsidy Xikang received from the central government.
=== Light transmission aggregometry === In light transmission aggregometry (LTA), platelet-rich plasma is placed between a light source and a photocell. Unaggregated plasma allows relatively little light to pass through. After adding an agonist, the platelets aggregate, increasing light transmission, which is detected by a photocell.
Sources: en.wikipedia.org
==== Acid pigmentation ==== In 2009 Luigi Garlaschelli, professor of organic chemistry at the University of Pavia, stated that he had made a full-size reproduction of the Shroud of Turin using only medieval technologies. His cloth was woven in the exact same manner and herringbone pattern by yarn type and weight as the Shroud. Garlaschelli placed a linen sheet over a volunteer and then rubbed it with an acidic pigment for the body. The shroud was then aged in an oven before being washed to remove the pigment. He then added blood stains, scorches and water stains to replicate the original. Giulio Fanti, professor of mechanical and thermic measurements at the University of Padua, commented that "the technique itself seems unable to produce an image having the most critical Turin Shroud image characteristics". Garlaschelli noted that the microscopic properties of his reproductions can't be exactly identical to the original, as accelerated and artificial aging lasting 4 hours cannot replicate the natural centuries the Shroud of Turin has gone through. He therefore considered the criticisms of those who claim a need for an absolute similarity as specious. Garlaschelli's reproduction was shown in a 2010 National Geographic documentary. Garlaschelli's technique included the bas-relief approach (described below) but only for the image of the face. The resultant image was visibly similar to the Turin Shroud, though lacking the uniformity and detail of the original.
== History == Ken and Linda Rosenthal founded the St. Louis Bread Company in 1987 after Ken visited sourdough bakery-café La Boulanger in San Francisco at the insistence of his brother. After being fascinated with the process of sourdough making, he was trained to make sourdough under instruction of the owner, Roger Brunello for a year. The first location was opened in Kirkwood, Missouri. The Rosenthals invested $150,000 and received a $150,000 Small Business Administration loan. Au Bon Pain Co., a public company, purchased the St. Louis Bread Company in 1993 for $23 million. In 1997, Au Bon Pain changed the company name to Panera, from a word that has roots in the Latin word for "breadbasket" (Classical pānārium, Vulgar pānāria) and is identical to the word for "breadbasket" in Spanish and Catalan. The original name was retained for locations in Missouri. At the same time, the St. Louis Bread Company renovated its 20 bakery-cafes in the St. Louis area. In May 1999, Au Bon Pain Co. sold the Au Bon Pain chain to the firm Bruckmann, Rosser, Sherrill & Co. for $78 million to focus on the Panera Bread chain. In 2000, Panera Bread moved its headquarters to Richmond Heights, Missouri. In 2007, Panera Bread purchased a 51% stake in Paradise Bakery & Café, a Phoenix metropolitan area-based concept with over 70 locations in 10 states, predominantly in the West and Southwest, for $21.1 million. The company purchased the balance of Paradise in June 2009.
=== Regional history prior to foundation of Lower Saxony === The name of Saxony derives from that of the Germanic confederation of tribes called the Saxons. Before the late medieval period, there was a single Duchy of Saxony. The term "Lower Saxony" was used after the dissolution of the stem duchy in the late 13th century to distinguish the parts of the former duchy ruled by the House of Welf from the Electorate of Saxony on one hand, and from the Duchy of Westphalia on the other.
Sources: en.wikipedia.org
Lance Forman (born October 1962); politician and businessman, who was a Member of the European Parliament (MEP) for London between 2 July 2019 and the United Kingdom's withdrawal from the EU; affiliated with Conservative Party, Forman was elected to the European Parliament as Brexit Party MEP; author of Forman's Games: The Dark Underside of the London Olympics and journalist for The Jewish Chronicle, The Telegraph, Daily Express, Metro (UK), The Spectator. Giles Fraser (born 27 November 1964) English Anglican priest of Jewish ancestry, journalist and broadcaster; regular contributor to Thought for the Day and The Guardian and a panellist on The Moral Maze, as well as an assistant editor of UnHerd; voted Stonewall Hero of the Year in 2012; lectures on moral leadership for the British Army at Defence Academy. Jonathan Freedland, journalist and leading liberal Zionist; worked on kibbutz in Israel with the Labour Zionist Habonim Dror (where Freedland had been a mentor to Sacha Baron Cohen); later writing for The Guardian, Daily Mirror, the London Evening Standard, The Jewish Chronicle, The New York Times, The New York Review of Books, Newsweek and The New Republic; in 2022 wrote highly acclaimed stage play Jews. In Their Own Words which the Royal Court Theatre described as a "searing and incisive play looking at the roots and damning legacy of antisemitism in Britain"; son of biographer and journalist Michael Freedland, and Israeli-born Sara Hocherman. He also writes fiction under the pseudonym Sam Bourne.
Traumatic acid is a monounsaturated dicarboxylic acid that occurs naturally in plants. The compound was first isolated from wounded bean plants by American chemists James English Jr. and James Frederick Bonner and Dutch scientist Arie Jan Haagen-Smit in 1939. Traumatic acid is a potent wound healing agent in plants ("wound hormone") that stimulates cell division near a trauma site to form a protective callus and to heal the damaged tissue. It may also act as a growth hormone, especially in inferior plants (e.g. algae). Traumatic acid is biosynthesized in plants by non-enzymatic oxidation of traumatin (12-oxo-trans-10-dodecenoic acid), another wound hormone. Traumatic acid, was among the first biologically active molecules isolated from plant tissues. This dicarboxylic acid was shown to be a potent wound healing agent in plant that stimulates cell division near a wound site, it derives from 18:2 or 18:3 fatty acid hydroperoxides after conversion into oxo- fatty acids. At normal conditions, traumatic acid is a solid, crystalline, water-insoluble substance. The salts and esters of traumatic acid are called traumatates. Traumatic acid is used as an intermediate in prostaglandin synthesis. It is also a constituent of some pharmaceutical products, such as the odontostomatologic gel Restomyl, due to its mucosal re-epithelialization activity.
== Early life == Rosanna Jeanne Reardon was born on June 8, 1985, in Seattle, Washington, where she was raised alongside her younger sister Molly Lu. She is of Italian, Croatian, German, and Irish ancestry. She was baptized Catholic. Throughout her childhood, she was known by friends and family as a "nerdy", "awkward" kid, and she struggled with dyslexia and ADHD in school. She originally wanted to become an actress, and after attending West Seattle High School and Pacific Lutheran University, she moved to Los Angeles to pursue acting. Prior to her YouTube career, Pansino worked as a teacher in China and as a Methodist church secretary. Pansino's interest in cooking was inspired by her father and grandmother, and she stated in 2014 that "...baking has always been a hobby of mine. I have always loved being creative with my food and making themed sweets for my friends."
=== Images of coins, flowers, and writing === Various people claim to have detected images of flowers on the shroud as well as coins over the eyes of the face in the image, writing, and other objects. However, a study published in 2011 by Lorusso and others subjected two photographs of the shroud to detailed modern digital image processing, one of them being a reproduction of the photographic negative taken by Giuseppe Enrie in 1931. They did not find any images of flowers or coins or writing or any other additional objects on the shroud in either photograph, they noted the faint images were "only visible by incrementing the photographic contrast" so they concluded that these signs might be linked to protuberances in the yarn and possibly also to the alteration and influence of the texture of the Enrie photographic negative during its development in 1931. The use of coins to cover the eyes of the dead is not attested for 1st-century Judaea. The existence of the coin images is rejected by most scientists.
Sources: en.wikipedia.org
No. TB-500 is a short synthetic peptide matching residues 17 to 23 of thymosin beta-4, while the parent protein contains 43 residues. The fragment lacks the rest of the protein sequence, so the two are related but not identical.
It consists of leucine, lysine, lysine, threonine, glutamic acid, threonine, and glutamine in that order. The N-terminal leucine is usually acetylated in the forms described in catalogues.
Controlled human data is limited, and most published findings come from cell culture or animal work. This makes it difficult to state clinical effects with confidence.
Desiccated storage at −20 °C is conventional, with −80 °C for extended periods. Vials should be warmed to room temperature before opening to prevent condensation on the powder.