If you have been reading about thymosin beta-4 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 2026-06-29. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Material is normally supplied as a lyophilised powder in a sealed vial. The powder is hygroscopic, so exposure to humid air leads to water uptake, caking and gradual loss of the fluffy texture that indicates a good freeze-dry. Vials are best kept sealed with desiccant, protected from light and stored cold. Letting a cold vial warm to room temperature before opening reduces condensation on the contents. Purity is normally reported from a chromatographic run, and that figure applies to the batch as tested rather than to the vial after repeated opening.
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.
Identity and purity are assessed with a small set of standard techniques. Reverse-phase high-performance liquid chromatography gives a purity estimate from peak area, usually recorded at 214 or 220 nanometers, where the peptide bond absorbs. Mass spectrometry confirms the expected molecular mass and can reveal truncated or oxidized species. Amino acid analysis or tandem mass spectrometry sequencing can verify the sequence itself. Additional quality attributes include water content, residual trifluoroacetic acid carried over from purification, and endotoxin where the material is intended for biological work.
The compound is most often distributed as a lyophilized powder, appearing white to off-white and forming a loose cake or fluffy solid. It is hygroscopic to some degree, so brief exposure to humid air can add water weight and complicate weighing. The peptide dissolves readily in water and in neutral aqueous buffers, and aqueous solubility is generally described as high, well above the concentrations used in typical assays. Some polar organic solvents are also usable, which matters when a concentrated stock is prepared before dilution into buffer.
| 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 |
Research interest in thymosin beta-4 fragments centres on actin sequestration, cell migration and tissue repair models. Most published work uses cultured cells or animal wound and cardiac preparations, and findings are generally described as preliminary. No fragment of this protein has been approved as a therapeutic product by major regulators. Reviews of the field note inconsistent dosing, delivery routes and outcome measures across studies, which complicates direct comparison. The material is best understood as a laboratory reagent with an active but unresolved research literature.
TB-500 is a catalogue name applied to a synthetic peptide related to thymosin beta-4, an actin-binding protein found in most mammalian cells. Suppliers do not use the label consistently: some describe it as the full 43-residue protein, others as a short fragment from the actin-binding region, and others as a related tetrapeptide. Because the name is commercial rather than chemical, two products sold under it may not contain the same molecule. This naming ambiguity is the first point to check in any description of the material.
The most frequently cited identity is a seven-residue fragment with the sequence LKKTETQ, taken from the actin-binding domain of the parent protein. A separate molecule, N-acetyl-seryl-aspartyl-lysyl-proline, often shortened to Ac-SDKP, derives from the same protein's N-terminal region and appears in overlapping literature. Reported molecular masses therefore differ between sources, and a mass value on its own does not establish which fragment is present. Confirmation requires a defined sequence rather than a single number.
Material sold under this label typically arrives as a freeze-dried powder in a sealed vial with a certificate of analysis. Such certificates usually report reversed-phase chromatography purity plus a mass confirmation, and stated purities commonly sit between 95 and 99 percent. Counter-ion identity, residual trifluoroacetate, water content, and peptide net weight are separate specifications that a certificate may or may not include. A purity figure alone does not establish sequence identity, so independent mass verification remains the practical check.
The designation TB-500 circulates in laboratory and catalog contexts without a single agreed definition. Most product listings apply it to an N-terminally acetylated seven-residue fragment of thymosin beta-4, while other listings attach the same label to the full 43-residue protein. Because the term is commercial rather than systematic, two entries bearing identical names may describe different molecules. Any documentation should therefore state which sequence a given sample is claimed to contain.
The fragment most often associated with the name carries the sequence Ac-LKKTETQ, matching residues 17 through 23 of thymosin beta-4. That region holds the actin-binding motif responsible for much of the parent protein's biochemical activity. Apart from N-terminal acetylation the peptide is unmodified and contains no disulfide bonds, so it shows little ordered secondary structure in solution. Full-length thymosin beta-4 is instead a 43-residue polypeptide of roughly 4.9 kDa found widely across mammalian cell types.
The uprising had been coordinated in advance across the three regions of Xikang (Ningshu, Yashu, and Kham). In Kham and Yashu, Liu's forces successfully staged uprisings, but the case of Ningshu was a different one. Liu's chief of staff, Wu Peiying, had attempted to sway He Guoguang, the leader of the KMT's Xichang garrison. He professed to join the plot. However, during the uprising itself, He remained loyal to the KMT, launching an attack on Wu's forces on 13 December and forcing them out of Ningshu. Chiang Kai-shek proceeded to strip Liu of his Xikang governorship, granting the role to He instead. By February 1950, the PLA entered Xichang, but He and Hu Zongnan had escaped to Taiwan. During the Chengdu Uprising, loyalist general Hu Zongnan occupied the city, but Liu's 24th Army had entered position along the Sichuan-Xikang highway to cut off a potential Nationalist retreat into Xikang. When Sichuan governor Wang Lingji attempted to do just that, his forces were defeated and he was captured on 25 December. By the 27th, Chengdu had been captured by the PLA; it was the last major city on the Chinese mainland to fall under Communist control. Communist historiography has praised Liu's actions as having contributed to the "peaceful liberation" of the Sichuan and Xikang regions.
=== Cellular uptake mechanisms === After nanogels exit the vasculature, they diffuse through the interstitial space into their target tissue. At the cellular level, nanogels can be internalized by a large number of different types of endocytosis that depend on the particle's size, shape, and surface properties. Endocytosis is the most common mechanism that starts with the nanogels engulfed by the cellular membrane. The nanogels are transported in intracellular vesicles for delivery to endosomes that eventually combine with lysosomes. Once lysosomes are released into the cytosol of a cell, they deliver their cargo immediately or move to the appropriate cellular compartment.
== Other == Barbie—Barbie represented the American way of life, because she was the ultimate consumer. New Math was a strong reaction to the launch of Sputnik, by changing the way mathematics was taught to school age children. The Kitchen Debate was an impromptu debate (through interpreters) between Vice President Richard Nixon and Soviet Premier Nikita Khrushchev at the opening of the American National Exhibition in Moscow, on July 24, 1959.
== History == Vegetable soup dates to ancient history. A 5th-century Roman cookbook included a recipe for "a forerunner of onion soup." Broth is mentioned by approximately the year 1000 and potage by the 1400s. Clifford Wright has stated that cabbage soup was important in medieval Italian cuisine. In central Appalachia, vegetable soup, also referred to as winter vegetable soup and country soup, is a traditional staple food and common dish during the months of December–February among Appalachian highlanders.
== June 11, 1915 (Friday) == Second Battle of Artois — Despite the Germans inflicting major casualties, French advanced 500 metres (550 yd) on a 300-metre (330 yd) front towards Neuville-Saint-Vaast, France. Battle of Hébuterne — The German launched the first of two counterattacks, with the first failing to dislodge the French. Second Battle of Garua — British and French forces formally took control of all garrisons around Garua, German Cameroon. Friar Leonard Melki and hundreds of other Christians are driven out of Mardin and massacred by Ottoman troops. Born: Magda Gabor, Hungarian actress, eldest sister of the Gabor sisters which included Eva and Zsa Zsa; as Magdolna Gábor, in Budapest, Austria-Hungary (present-day Hungary) (d. 1997)
Sources: en.wikipedia.org
For example, an adolescent involved in sports, would likely surround themselves with like-minded active and competitive people. Personal expressiveness, as coined by psychologist A. S. Waterman, are the activities that we choose to express and connect with our "daimon" through subjective experiences. Finally, goal-directed behaviours, are developed through goal setting, where individuals work towards identity establishment. Adolescents recognize their passions, abilities and talents and aim to fulfill their goals and behave in a way that appeases their true self. The study on adolescents was conducted in Italy, Chile and the United States, which produced slightly varied outcomes. Outcomes were contingent on availability, access and choice of opportunities (activities). Socioeconomic context also affected the results, as not all individuals could access the activities that may be more in-line with their true selves. The Personally Expressive Activities Questionnaire (PEAQ) was used to conduct the study. Adolescence was the youngest age group that the PEAQ was used on. The PEAQ asked adolescents to self-report on activities they participate in and describe themselves with self-defining activities. It was reported that 80% of adolescents defined themselves with two to four self-defining activities signifying an understanding in adolescence of self-concept through the domains of leisure, work and academia.
== Further reading == Green Analytical Methods and Miniaturized Sample Preparation techniques for Forensic Drug Analysis. 2025. doi:10.1016/C2022-0-02711-2. ISBN 978-0-443-13907-9. Janusz Pawliszyn: Handbook of Solid Phase Microextraction, Chemical Industry Press, 2009. Pawliszyn J.: Solid Phase Microextraction: Theory and Practice, Wiley-VCH, 1997. Pawliszyn J.: Applications of Solid Phase Microextraction, Royal Society of Chemistry, 1999.
Shotgun sequencing is a sequencing method designed for analysis of DNA sequences longer than 1000 base pairs, up to and including entire chromosomes. This method requires the target DNA to be broken into random fragments. After sequencing individual fragments using the chain termination method, the sequences can be reassembled on the basis of their overlapping regions. This method was heavily used in the Human Genome Project.
In 1816, as the Gazette was in decline, businessmen Frederick Heiskell and Hugh Brown established a newspaper, the Knoxville Register. Along with the Register, Heiskell and Brown published a pro-emancipation newsletter, the Western Monitor and Religious Observer, as well as books such as John Haywood's Civil and Political History of the State of Tennessee (1823), one of the state's first comprehensive histories. The Register celebrated the move of East Tennessee College (the new name of Blount College following its rechartering in 1807) to Barbara Hill in 1826, and encouraged the trustees of the Knoxville Female Academy, which had been chartered in 1811, to finally hire a faculty and hold its first classes in 1827. In the April 1839 issue of the Southern Literary Messenger, a traveler who had recently visited Knoxville described the people of the city as "moral, sociable and hospitable," but "with less refinement of mind and manners" than people in older towns. In 1842, English travel writer James Gray Smith reported that the city was home to a university, an academy, a "ladies' school," three churches, two banks, two hotels, 25-30 stores, and several "handsome country residences" occupied by people "as aristocratic as even an Englishman... could possibly desire."
=== Wound healing === Aroa Biosurgery Limited first distributed OFM commercially in 2012 as Endoform™ Dermal Template (later Endoform™ Natural) through a distribution partnership with Hollister Incorporated (IL, USA). Endoform™ Natural and Endoform™ Antimicrobial (0.3% ionic silver w/w), are single layers of OFM used in the treatment of acute and chronic wounds, including diabetic foot ulcers (DFU) and venous leg ulcers (VLU). Endoform™ Natural has been shown to accelerate wound healing of DFU. The wound product Symphony™ combines OFM and hyaluronic acid and is designed to support healing during the proliferative phase particularly in patients whose healing is severely impaired or compromised due to disease.
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.
Short transit at ambient temperature is generally tolerated, but long-term storage at room temperature is not recommended. Heat, moisture, and light all accelerate degradation. Cold, dry, dark storage is the conventional choice.