The short version of Thymosin beta-4 fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-02-21. Anything still debated is marked as such rather than presented as settled.
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.
Lyophilized peptide powder is normally held desiccated at −20 °C, with −80 °C used for longer storage periods. Allowing a sealed vial to reach room temperature before opening is standard practice, because condensation forming on cold powder introduces moisture. Once dissolved, solutions are typically kept cold and shielded from light. Repeated freeze-thaw cycles are avoided because they encourage aggregation and gradual loss of material. These conventions are general to synthetic peptides rather than unique to any one sequence.
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.
| Property | Value | Notes |
|---|---|---|
| Common synonyms | Thymosin beta-4 fragment; TB4 fragment | Naming is inconsistent across suppliers and publications |
| Reported sequence | Ac-LKKTETQ | Corresponds to residues 17-23 of the parent protein |
| Frequently cited registry number | 77591-33-4 | Associated with full-length thymosin beta-4 rather than the fragment |
| Common supplied form | Freeze-dried solid | Often presented as an acetate or trifluoroacetate salt |
| Regulatory treatment | Varies by country | Frequently handled as a research chemical; not broadly approved as a therapeutic |
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.
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.
Several names appear in scientific and commercial contexts for this peptide. The label TB-500 is informal and does not follow standard biochemical nomenclature. Research articles more often describe the compound as a thymosin beta-4 fragment, Tβ4 fragment, or by its sequence Ac-LKKTETQ. Confusing TB-500 with full-length thymosin beta-4 can lead to incorrect assumptions about activity because the fragment lacks the remaining residues of the parent protein. The relationship between fragment and parent protein remains an active area of study.
Lyophilised material is stable for extended periods when kept dry and cold, and suppliers typically recommend storage well below freezing. Once dissolved, the peptide is handled at refrigeration temperatures and used within a short period, because peptide bonds and the acetylated terminus can be affected by repeated freeze-thaw cycles, proteases, or extreme pH. Bacteriostatic water and saline are both described as solvents, although preservatives can interfere with some analytical workflows. Reconstituted solutions are inspected for particulates before use.
Sports authorities classify the peptide as a prohibited substance, and it appears on the World Anti-Doping Agency list under peptide hormones, growth factors, and related substances. Racing jurisdictions for horses and dogs have issued separate restrictions, and several national bodies treat it as a controlled or prescription-only item. As a research chemical it is sold without a therapeutic indication, and labels usually state that the product is not for human or veterinary use. Regulatory treatment therefore varies by country.
==== UV-C ==== UV-C does not penetrate as deeply as other methods. As such, its direct antimicrobial effect is limited to the surface only. Its DNA damage effect produces cyclobutane-type pyrimidine dimers. Besides the direct effects, UV-C also induces resistance even against pathogens not yet inoculated. Some of this induced resistance is understood, being the result of temporary inactivation of self-degradation enzymes like polygalacturonase and increased expression of enzymes associated with cell wall repair.
== Polymorphs == Calcium carbonate crystallizes in three anhydrous polymorphs, of which calcite is the thermodynamically most stable at room temperature, aragonite is only slightly less so, and vaterite is the least stable.
=== Photographic records === For the benefit of the patient and the physician–surgeon, a photographic history of the entire rhinoplastic procedure is established; beginning at the pre-operative consultation, continuing during the surgical operation procedures, and concluding with the post-operative outcome. To record the "before-and-after" physiognomies of the nose and the face of the patient, the specific visual perspectives required are photographs of the nose viewed from the anteroposterior (front-to-back) perspective; the lateral view (profiles), the worm's-eye view (from below), the bird's-eye view (overhead), and three-quarter-profile views.
Sources: en.wikipedia.org
In 2009, Chipotle released an app for the iPhone that allows users to find nearby Chipotle locations, place an order, and prepay with a credit card. In 2013, Chipotle released an Android app that allows users to locate nearby Chipotle locations, place an order, prepay with a credit or gift card, and access favorites and recent orders. In late 2021, the company added a non-food item to the menu—cilantro soap. According to published reports, the soap sold out the day after its release. The soap was produced after an August 2021 Instagram post of what was thought to be a mock photo of the product. It was an effort to engage fans and haters of the herb that, "plays into a larger trend of turning digital moments into real life experiences," according to Chris Brandt, Chipotle's Chief Marketing Officer. Chipotle uses green marketing and its "Food with Integrity" platform to boost its brand image.
The US lost two nuclear submarines during this time: USS Thresher due to equipment failure during a test dive while at its operational limit, and USS Scorpion due to unknown causes. During the Indo-Pakistani War of 1971, the Pakistan Navy's Hangor sank the Indian frigate INS Khukri. This was the first sinking by a submarine since World War II. During the same war, Ghazi, a Tench-class submarine on loan to Pakistan from the US, was sunk by the Indian Navy. It was the first submarine combat loss since World War II. In 1982 during the Falklands War, the Argentine cruiser General Belgrano was sunk by the British submarine HMS Conqueror, the first sinking by a nuclear-powered submarine in war. Some weeks later, on 16 June, during the Lebanon War, an unnamed Israeli submarine torpedoed and sank the Lebanese coaster Transit, which was carrying 56 Palestinian refugees to Cyprus, in the belief that the vessel was evacuating anti-Israeli militias. The ship was hit by two torpedoes, managed to run aground but eventually sank. There were 25 dead, including her captain. The Israeli Navy disclosed the incident in November 2018.
The prevalence of abdominal obesity is increasing in Western populations, possibly due to a combination of low physical activity and high-calorie diets, and also in developing countries, where it is associated with the urbanization of populations. Other environmental factors, such as maternal smoking, estrogenic compounds in the diet, and endocrine-disrupting chemicals may be important also. Hypercortisolism, such as in Cushing's syndrome, also leads to central obesity. Many prescription drugs, such as dexamethasone and other steroids, can also have side effects resulting in central obesity, especially in the presence of elevated insulin levels. There are various ways of measuring abdominal obesity including: Absolute waist circumference (>102 cm (40 in) in men and >88 cm (35 in) in women) Waist–hip ratio (the circumference of the waist divided by that of the hips of >0.9 for men and >0.85 for women) Waist-stature ratio (waist circumference divided by their height, >0.5 for adults under 40 and >0.6 for adults over 50) Sagittal Abdominal Diameter
== History == In 1939, Martin Kamen and Samuel Ruben of the Radiation Laboratory at Berkeley began experiments to determine if any of the elements common in organic matter had isotopes with half-lives long enough to be of value in biomedical research. They synthesized 14C using the laboratory's cyclotron accelerator and soon discovered that the atom's half-life was far longer than had been previously thought. This was followed by a prediction by Serge A. Korff, then employed at the Franklin Institute in Philadelphia, that the interaction of thermal neutrons with 14N in the upper atmosphere would create 14C. It had previously been thought that 14C would be more likely to be created by deuterons interacting with 13C. At some time during World War II, Willard Libby, who was then at Berkeley, learned of Korff's research and conceived the idea that it might be possible to use radiocarbon for dating.
Sources: en.wikipedia.org
=== The Copa América final (1975) === The renamed and decentralised 1975 Copa América produced Colombia's first deep run in a continental tournament. Coached by Efraín Sánchez, the goalkeeper of the 1962 squad, Colombia won all four group matches against Paraguay and Ecuador, scoring seven and conceding one. In the semi-final they overwhelmed the defending champions Uruguay 3–0 at the Estadio El Campín through Edgar Angulo, Ortiz and Ernesto Díaz; the return at the Estadio Centenario finished 1–0 to Uruguay, whose Fernando Morena converted an early penalty before being sent off and whose team missed two further spot-kicks. With the sides level on points, Colombia advanced on goal difference. The final against Peru was the first in the competition's history to be decided over multiple legs. Ponciano Castro settled the opening match in Bogotá on 16 October with a long-range strike; Peru answered a week later at the Estadio Nacional in Lima, Juan Carlos Oblitas and Oswaldo Ramírez scoring inside the first half for a 2–0 win that levelled the tie on points and forced a decider on neutral ground. At the Estadio Olímpico in Caracas on 28 October, Hugo Sotil — flown in from Barcelona — scored the only goal before 30,000 spectators, and Peru claimed a second continental title. Ernesto Díaz finished as the tournament's joint leading scorer with four goals, a total that still ranks among the highest by a Colombian at the Copa América.
Benzene at The Periodic Table of Videos (University of Nottingham) International Chemical Safety Card 0015 USEPA Summary of Benzene Toxicity NIOSH Pocket Guide to Chemical Hazards Benzene from PubChem Dept. of Health and Human Services: TR-289: Toxicology and Carcinogenesis Studies of Benzene Video Recording of Sir John Cadogan giving a lecture on Benzene at the Royal Institution, 22 September 1991 Substance profile NLM Hazardous Substances Databank – Benzene
== Activation == Chymotrypsin is synthesized in the pancreas. Its precursor is chymotrypsinogen. Trypsin activates chymotrypsinogen by cleaving peptidic bonds in positions Arg15 – Ile16 and produces π-chymotrypsin. In turn, aminic group (-NH3+) of the Ile16 residue interacts with the side chain of Asp194, producing the "oxyanion hole" and the hydrophobic "S1 pocket". Moreover, chymotrypsin induces its own activation by cleaving in positions 14–15, 146–147, and 148–149, producing α-chymotrypsin (which is more active and stable than π-chymotrypsin). The resulting molecule is a three-polypeptide molecule interconnected via disulfide bonds.
==== Class actions ==== In August 2015, Fairfax Media and the ABC's Four Corners program reported on the employment practices of certain 7-Eleven franchisees in Australia. The investigation found that many 7-Eleven employees were being underpaid at rates of around A$10 to A$14 per hour before tax, well under the legally required minimum award rate of A$24.69 per hour. The Four Corners investigation into 7-Eleven won a Walkley Award in 2015. Franchisees underpaying their staff would typically maintain rosters and pay records that appeared to show the employee being paid the legally required rate; however, these records only included half of the hours the employee actually worked in a week. Employees were then paid on the basis of these records, resulting in them effectively being paid half the legally required rate. It was also reported that workers were often not paid loadings and penalty rates that they are legally entitled to, for working overtime hours, nights, weekends, and public holidays. After these reports came to light and received widespread attention, some employees had alleged to Fairfax Media that they had begun to be paid correctly through the 7-Eleven payroll system; however, they were then asked by the franchisee to pay back half their wages in cash. 7-Eleven subsequently announced they would fund an inquiry to investigate instances of wage fraud. The inquiry was conducted by an independent panel chaired by former Australian Competition & Consumer Commission chairman Allan Fels, and with the support of professional services firm Deloitte.
Studies of twin adults indicate a 0.36 to 0.48 genetic influence on the likelihood of developing migraine. However, few studies examine non-European populations or distinguish between migraine with aura and migraine without aura. It is clear from family and population studies that migraine is a complex disorder, where numerous genetic risk variants exist, and where each variant increases the risk of migraine marginally. It is also known that having several of these risk variants increases the risk by a small to moderate amount. Single gene disorders that result in migraine are rare. One of these is known as familial hemiplegic migraine, a type of migraine with aura, which is inherited in an autosomal dominant fashion. Three main genes are involved in familial hemiplegic migraine via ion transport: CACNA1A, ATP1A2, and SCN1A. Another genetic disorder that has been associated with migraine is CADASIL syndrome (cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy). Despite some similarities in symptoms, ICHD-3 recommends using the diagnosis "headache attributed to CADASIL" (code 6.8.1) rather than migraine with aura (MA) or migraine without aura (MO) (codes 1.1 and 1.2). The TRPM8 gene, which codes for a cation channel, has been linked to migraine. One meta-analysis found a protective effect from angiotensin converting enzyme polymorphisms on migraine. The common forms of migraine are polygenetic, where common variants of numerous genes contribute to the predisposition for migraine.
Sources: en.wikipedia.org
The leading proposal involves sequestration of monomeric actin, which would alter cytoskeletal turnover and cell movement. The actin-binding motif shared with the parent protein is central to that idea. Direct confirmation in whole organisms remains limited.
Very few controlled human studies focus on the seven-residue sequence itself. Most clinical data concern the full-length protein in cardiac or ophthalmic settings. Conclusions drawn for one form should not be assumed to transfer to the other.
Detection normally relies on reversed-phase liquid chromatography paired with mass spectrometry. Chromatographic retention time establishes the expected elution window, and the mass spectrum confirms the molecular ion. Immunoassays exist but can cross-react with related peptides.
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.