If you have been reading about thymosin beta-4 fragment 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 2026-03-07. 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.
Thymosin beta-4 is a 43-residue actin-binding protein found in most mammalian cell types, where it participates in cytoskeletal regulation and cell migration. TB-500 represents only a short fragment of that protein and does not include the remaining residues. Whether the isolated fragment reproduces the full range of activities reported for the intact protein remains an open question. Researchers commonly treat the two as related but distinct entities when comparing results.
Dry peptide powder is commonly kept at −20 °C in a desiccated container away from light, a practice that limits moisture uptake and oxidation. Once dissolved, solutions are generally held at 2–8 °C for short periods or frozen at −20 °C or lower for longer storage, with repeated freeze-thaw cycles avoided. Hydrolysis and oxidation are the main degradation routes for peptides in solution, and both accelerate at higher temperature or extreme pH. Published stability data specific to TB-500 are limited, so shelf life should be treated as uncertain.
Identity and purity checks for peptide material typically combine reversed-phase high-performance liquid chromatography with mass measurement, since retention time alone cannot confirm a sequence. Mass measurement verifies the expected molecular mass within instrument tolerance, while chromatographic peak area provides a purity estimate. Anti-doping analysis of urine uses related but more sensitive workflows, sometimes after solid-phase extraction. For research material, batch documentation, certificate content, and independent testing are common points of scrutiny, because supply chains outside pharmaceutical regulation vary widely in the paperwork they provide.
| 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 |
Research peptides are typically supplied as a white to off-white lyophilised powder in a sealed vial. The dry solid is more stable than a solution and is normally kept refrigerated or frozen until use. Dissolution is usually done in water, phosphate-buffered saline or a similar aqueous medium, depending on the assay. Because the material is hygroscopic and easily contaminated, opening vials in a low-humidity environment and recording the lot number before use are standard laboratory practices.
Once in solution, short peptides are generally less stable than the dry powder, and repeated freeze-thaw cycles are a common cause of loss. Laboratory guidance usually calls for aliquoting on first dissolution and storing aliquots at -20 °C or below, away from light. Adsorption to plastic and glass surfaces can lower measured concentration, particularly at low concentrations, so container material and buffer choice can affect results. Visible cloudiness, colour change or unexpected precipitate is a signal to re-check the material.
TB-500 refers to a synthetic peptide fragment derived from the actin-binding region of thymosin beta-4, a protein present in most mammalian cells. The full protein contains forty-three amino acids, while the commonly sold fragment is a much shorter acetylated sequence, often cited as LKKTETQ. The fragment retains part of the actin-binding motif but lacks the remainder of the parent protein. Material sold under this name is usually lyophilized powder intended for laboratory research, and it is not a finished pharmaceutical product.
Proposed activity centers on actin sequestration and on the movement of cells during repair processes. In cell culture and animal models, the fragment has been associated with migration, tube formation, and tissue remodeling. These observations are frequently described as preliminary, because most published work uses rodent or in vitro systems rather than controlled human trials. Whether the short fragment reproduces the effects of the full protein remains an open question, and the relationship between dose, route, and measured outcome is not well characterized.
The compound circulates in the literature as a research reagent rather than an approved therapeutic. Regulatory agencies in several countries have not authorized it for medical use, and sporting bodies list related thymosin beta-4 peptides among prohibited substances. Suppliers typically market it with a purity figure and a certificate of analysis, while peer-reviewed clinical reports remain sparse. Discussions therefore often separate laboratory findings from anecdotal reports, and reviewers tend to note the small size and methodological limits of the available studies.
==== Hemisphere effect ==== The northern and southern hemispheres have atmospheric circulation systems that are sufficiently independent of each other that there is a noticeable time lag in mixing between the two. The atmospheric 14C/12C ratio is lower in the southern hemisphere, with an apparent additional age of about 40 years for radiocarbon results from the south as compared to the north. This is because the greater surface area of ocean in the southern hemisphere means that there is more carbon exchanged between the ocean and the atmosphere than in the north. Since the surface ocean is depleted in 14C because of the marine effect, 14C is removed from the southern atmosphere more quickly than in the north. The effect is strengthened by strong upwelling around Antarctica.
Although the totality of the data that have been reviewed provides reassurance, pancreatitis will continue to be considered a risk associated with these drugs until more data are available; both agencies continue to investigate this safety signal." Lawsuits have been filed in which plaintiffs who developed pancreatic cancer claim that DPP-IV inhibitors or incretins had a causative role in the development of their cancers.
"To the extent that the attacks on Georgian villages, police and peacekeepers were conducted by South Ossetian militia, self-defence in the form of on-the-spot reactions by Georgian troops was necessary and proportionate and thus justified under international law. On the other hand, the offensive that started on 7 August, even if it were deemed necessary, was not proportionate to the only permissible aim, the defence against the on-going attacks from South Ossetia."
The size of a burn is measured as a percentage of total body surface area (TBSA) affected by partial thickness or full thickness burns. First-degree burns that are only red in color and are not blistering are not included in this estimation. Most burns (70%) involve less than 10% of the TBSA. Unit of measuring burns is VSD as 10% TBSA is equal to 1VSD. There are a number of methods to determine the TBSA, including the Wallace rule of nines, Lund and Browder chart, and estimations based on a person's palm size. The rule of nines is easy to remember but only accurate in people over 16 years of age. More accurate estimates can be made using Lund and Browder charts, which take into account the different proportions of body parts in adults and children. The size of a person's handprint (including the palm and fingers) is approximately 1% of their TBSA.
Sources: en.wikipedia.org
Freeman also narrated The True Story of Glory Continues, a documentary about the 54th Massachusetts Infantry Regiment. In 1992, he appeared in Clint Eastwood's western Unforgiven, which won four Academy Awards including Best Picture. The film depicts William Munny (Eastwood), an aging outlaw and killer who takes on one more job with old friend Ned Logan (Freeman). Unforgiven was widely acclaimed, with one critic calling Freeman's performance "outstanding". Also in 1992 Freeman starred in the John G. Avildsen directed drama The Power of One acting opposite Stephen Dorf and John Gielgud in a loose adaptation of Bryce Courtenay's 1989 novel of the same name, in which he plays boxing coach Geel Piet. In 1993, Freeman made his directorial debut with the drama Bopha!, which tells the story of a black policeman (Danny Glover) during South Africa's apartheid era. Bopha! was well-received, in particular for Freeman's directing. Hal Hinson of The Washington Post wrote: "Freeman lays out the father-son dynamics with great skill and very little fuss. There's no hysteria in his approach; instead, he sticks to the facts, relying on his cast to provide the emotion. The result is a surprisingly powerful, insightful film." Kenneth Turan from Los Angeles Times also complimented Freeman's direction but thought the film was "more predictable than powerful". In 1994, Freeman portrayed Red, the redeemed convict in Frank Darabont's acclaimed drama The Shawshank Redemption, with co-star Tim Robbins. It is based on the 1982 Stephen King novella Rita Hayworth and the Shawshank Redemption.
== Research == A research study conducted in 2019 on a pregnant couple with a child that has Harlequin Ichthyosis talked about characteristic sonographic features. Eclabium and ectropion can be seen in the ultrasound. The mouth is persistently open and restriction of limb movement is also seen. Another Research was inducted on the use of retinoids and whether or not they are the only way to treat Harlequin Ichthyosis. The research titled survival without systemic retinoids mentions how the chances of survival are very low regardless of retinoid treatment. According to this study two neonates were able to survive with intensive care but no retinoids. Further research on the types of Ichthyosis and receiving genetic counseling for the condition is still being reviewed. The importance of neonatologist, a pediatric dermatologist, a geneticist and other specialists is discussed in this study. Their involvement can help better the treatment plan for Harlequin Ichthyosis patients and help ease symptoms such as eclabium.
=== NAADP activators === NAADP is charged and cannot cross cell membranes. Therefore, an inactive, lipophilic ester precursor (NAADP/AM) has been synthesised which crosses membranes and rapidly regenerates NAADP in the cytosol following the action of endogenous esterases. Caged NAADP is an inactive, membrane-impermeant analog of NAADP that can be introduced into cells by microinjection or a patch pipette. Flash photolysis with a UV light source rapidly converts this into NAADP, allowing the experimenter to precisely manipulate NAADP levels in time and space.
Sources: en.wikipedia.org
The Mysterious Island (French: L'Île de Calypso, literally "Calypso's Island"), sometimes advertised with the subtitle Ulysse et le géant Polyphème ("Odysseus and the Giant Polyphemus"), is a 1905 French short silent film by Georges Méliès. It was sold by Méliès's Star Film Company and is numbered 750–752 in its catalogues. The film is four minutes long. Méliès plays Odysseus in the film, which is based on two completely separate scenes from the Odyssey, combining Ogygia, Calypso's island in the Ionian Sea, with Polyphemus's cave near Mount Etna in Sicily. The film's special effects are worked with stage machinery, multiple exposures, substitution splices, and dissolves. Polyphemus's eye is puppeteered with two strings, while the giant arm is probably Méliès's own.
=== Genetic factors === Genetic factors such as HLA-DR1B1, TRAF1, PSORS1C1 and microRNA 146a are associated with difficult-to-treat rheumatoid arthritis, other gene polymorphisms seem to be correlated with response to biologic modifying anti-rheumatic drugs (bDMARDs). The next one is the FOXO3A gene region been reported as associated with the worst disorder. The minor allele at FOXO3A summons a differential response of monocytes in RA patients. FOXO3A can provide an increase in pro-inflammatory cytokines, including TNFα. Possible gene polymorphism: STAT4, PTPN2, PSORS1C1 and TRAF3IP2 genes had been correlated with response to TNF inhibitors.
Hyaluronidase increases tissue permeability to accelerate the absorption of other enzymes into tissues. Some snake venoms carry fasciculins, like the mambas (Dendroaspis), which inhibit cholinesterase to make the prey lose muscle control.
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.
Standard practice is a desiccated container at −20 °C, protected from light and kept sealed between uses. Letting the vial reach room temperature before opening reduces condensation on the powder. Repeated warming and cooling of the whole container is generally avoided.