Everything below concerns thymosin beta-4. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-02-10. Numbers and descriptions here follow the published literature rather than marketing material.
TB-500 is a synthetic seven-residue peptide whose sequence, LKKTETQ, matches the N-terminal actin-binding region of thymosin beta-4. It is usually supplied in an N-terminally acetylated form, a modification that blocks the free amino terminus and can influence behavior in solution. In the research literature the same sequence appears under several names, including thymosin beta-4 fragment and shortened thymosin beta-4. Because it is a short peptide rather than the full 43-residue parent protein, its measured properties differ from those reported for thymosin beta-4 as a whole, and the two are not interchangeable in experimental design.
Thymosin beta-4 itself is a small, widely expressed protein that sequesters monomeric actin and participates in cell migration, angiogenesis, and tissue repair. Researchers have examined the shortened fragment as a possible mimic of some of these activities, reasoning that the actin-binding motif lies within the first few residues. Binding to monomeric actin has been observed in cell-free systems. Whether the fragment reproduces the broader effects of the full protein in living tissue remains an open question, and findings from animal models are frequently cited without a clear bridge to human physiology.
Discussion of TB-500 appears in several distinct literatures that rarely cite one another. Peer-reviewed studies usually describe in vitro assays or small animal experiments and are cautious about extrapolation. Veterinary and sports communities circulate anecdotal reports with limited methodological detail. Commercial listings add a third layer, often using the name interchangeably with thymosin beta-4 even though the two molecules differ in size and sequence. Regulatory status varies by country, and the compound is not a licensed medicine in most jurisdictions, so readers comparing sources should check which molecule and which purity each source actually describes.
Peptide bonds are susceptible to hydrolysis under extreme pH and to enzymatic cleavage if proteases are present. Heat, oxidising agents, and prolonged exposure to light also contribute to loss of material. Aggregation can occur at high concentrations or in certain buffer systems, and it may not be visible to the eye. Storage at -20 C or below is typical for both powder and aliquoted solutions, and desiccation of the powder is preferred.
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography together with mass spectrometry. The chromatogram provides a purity estimate as a percentage of total peak area, while the mass spectrum confirms that the observed mass matches the expected value. Amino acid analysis or tandem mass spectrometry sequencing can provide additional confirmation. Reported purity figures depend on the column, gradient, and detection wavelength, so values from different laboratories are not directly comparable without method details.
| Property | Value | Notes |
|---|---|---|
| Molecular class | Synthetic peptide | N-terminal fragment of thymosin beta-4 |
| Residue count | Seven | Sequence LKKTETQ |
| Approximate mass | 889 Da | Acetylated seven-residue peptide |
| Common synonyms | TB4 fragment, TB500 | Not identical to full-length TB4 |
| Reported activity | Actin binding | Observed mainly in cell-free systems |
Interest in the fragment grew during the 1990s and 2000s, when it moved from laboratory work into sports and supplement markets. Anti-doping bodies added thymosin beta-4 fragments to prohibited lists, and a small number of adverse analytical findings have been reported in competition testing. Published controlled human trials remain scarce. Most mechanistic evidence comes from cell culture and animal models, and those studies examine endpoints such as cell migration, wound closure and inflammation markers. That evidence supports research interest but does not establish clinical benefit, and broad regenerative claims should be read as unverified.
TB-500 is a short synthetic peptide sold under a trade name rather than a systematic chemical name. Suppliers usually describe it as a fragment of thymosin beta-4 and ship it as a lyophilised powder intended for laboratory use. Because the label is commercial, the exact sequence attributed to it is not fully consistent across catalogues, and some listings present a seven-residue peptide while others describe related fragments of similar length. It is not an approved medicine in any major jurisdiction, and it is handled as a research chemical.
Thymosin beta-4 itself is a natural peptide of 43 residues found in many cell types and body fluids. Its best-characterised function is binding and sequestering actin monomers, which influences cytoskeletal dynamics. The sequence most often associated with TB-500, LKKTETQ, corresponds to part of that actin-binding region. A different fragment, Ac-SDKP, is also derived from the same parent peptide and is studied in its own right, which is one reason discussions of thymosin fragments can become confusing. The two are structurally distinct and are not interchangeable.
Published research on the intact protein is substantial, covering actin regulation, cell migration, and wound models. Research using the heptapeptide fragment specifically is far smaller, and much of the circulating material originates in supplier documentation rather than peer-reviewed reports. Where fragment studies do exist, they often employ different sequences, chain lengths, or terminal modifications, which complicates direct comparison across papers. Readers encountering claims about TB-500 should therefore separate evidence about thymosin beta-4 from evidence about the fragment itself.
Discussion of the compound frequently appears alongside other short peptides described as fragments of larger proteins. That grouping is convenient but can be misleading, because fragment length, charge, and modification state determine how a peptide behaves in solution and in any experimental system. A seven-residue acetylated peptide and a full-length protein differ in mass by roughly an order of magnitude, and they cannot be assumed to share distribution or binding properties. Precision about which molecule is under discussion is the single most useful step when reading such material.
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.
Purity is normally assessed by reversed-phase HPLC, with the main peak reported as a percentage of total peak area, while identity is confirmed by mass spectrometry. Electrospray and MALDI-TOF instruments are both used, and the observed mass is compared with the value calculated from the stated sequence. Ion-exchange or size-exclusion methods appear where aggregation or charge variants are of interest. Water content, counter-ion content and residual trifluoroacetate from purification are separate variables that can shift the measured mass and should be weighed when reading a certificate of analysis.
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.
A newer process, solid oxide membrane technology, involves the electrolytic reduction of MgO. At the cathode, Mg2+ ion is reduced by two electrons to magnesium metal. The electrolyte is yttria-stabilized zirconia (YSZ). The anode is a liquid metal. At the YSZ/liquid metal anode O2− is oxidized. A layer of graphite borders the liquid metal anode, and at this interface carbon and oxygen react to form carbon monoxide. When silver is used as the liquid metal anode, there is no reductant carbon or hydrogen needed, and only oxygen gas is evolved at the anode. It was reported in 2011 that this method provides a 40% reduction in cost per pound over the electrolytic reduction method.
Some conducting materials may pass electrons to form a difference in electrical charge at the joint. This results in a structure similar to a capacitor and creates an attractive electrostatic force between the materials.
It had been reported during the season that he had appeared disenchanted as the supplements scandal continued to heavily impact on the club, and in their Round 19 loss to Greater Western Sydney, Carlisle was reported to have yelled "This club is fucked" as he walked to the interchange bench. In October 2015, after much deliberation, Carlisle nominated St Kilda over Carlton as the club he wished to be traded to from Essendon. He was officially traded to St Kilda on 21 October. During his first pre-season with St Kilda, Carlisle and 33 other players who were at Essendon were found guilty of using a banned performance-enhancing substance, thymosin beta-4, as part of Essendon's sports supplements program during the 2012 season. He and his team-mates were initially found not guilty in March 2015 by the AFL Anti-Doping Tribunal, but a guilty verdict was returned in January 2016 after an appeal by the World Anti-Doping Agency. He was suspended for two years which, with backdating, ended in November 2016; as a result, he served approximately fourteen months of his suspension and missed the entire 2016 AFL season. He had also received a two-match internal suspension at St Kilda after footage emerged of him using recreational drugs, but the club later waived it, determining that it was served concurrently with the season-long ban. Carlisle played all 22 games in his first proper season at St Kilda in 2017, following the trade and suspension. The Saints finished mid-table that year with 11 wins and 11 losses.
== Adverse effects == Adverse effects of yohimbine in humans at high doses include hypertension (high blood pressure), tachycardia (rapid heartbeat), agitation, hypervigilance, anxiety, tremors, nausea, and urinary frequency. The drug is described as producing a psychoactive state of considerable anxiety along with tenseness, restlessness, and irritability and as being "extremely unpleasant", at least at the assessed doses. In animals, yohimbine likewise produces effects suggestive of severe anxiety. Yohimbine has been used in animals as a model of anxiety in the evaluation of novel anxiolytics.
Sources: en.wikipedia.org
In other countries, such as Australia and the UK, the operation is commonly performed with the person undergoing a general anaesthetic. All cases require a careful follow-up with an eye doctor (ophthalmologist or optometrist) for a number of years. Frequently, vision is greatly improved after the surgery, but even if the actual visual acuity does not improve, because the cornea is a more normal shape after the healing is completed, people can more easily be fitted with corrective lenses. Complications of corneal transplants are mostly related to vascularization of the corneal tissue and rejection of the donor cornea. Vision loss is very rare, though difficult-to-correct vision is possible. When rejection is severe, repeat transplants are often attempted, and are frequently successful. Keratoconus will not normally reoccur in the transplanted cornea; incidences of this have been observed, but are usually attributed to incomplete excision of the original cornea or inadequate screening of the donor tissue. The long-term outlook for corneal transplants performed for keratoconus is usually favorable once the initial healing period is completed and a few years have elapsed without problems. One way of reducing the risk of rejection is to use a technique called deep anterior lamellar keratoplasty (DALK). In a DALK graft, only the outermost epithelium and the main bulk of the cornea, the stroma, are replaced; the person's rearmost endothelium layer and the Descemet's membrane are left, giving some additional structural integrity to the postgraft cornea.
== Ester terminology == IUPAC states normatively that carbamate "esters are often called urethanes or urethans, a usage that is strictly correct only for the ethyl esters." However, as a descriptive matter, the IUPAC recognizes that "An alternative term for the compounds R2NC(=O)OR' (R' not = H), esters of carbamic acids, R2NC(=O)OH, in strict use limited to the ethyl esters, but widely used in the general sense".
=== Jennifer Bevan === Jennifer “Jenni” Bevan (Amy James-Kelly) is a Labour Party politician who defeats Henry Muck in the 2024 general election and is appointed Minister of State for Industry. At the start of series 4, she introduces an online safety bill tightening age-verification rules for porn aggregators such as Siren, triggering a sharp drop in Siren’s stock and prompting Whitney Halberstram, CFO of Siren's payment processor Tender, to pivot away from pornography and gambling clients. Whitney seeks Bevan’s regulatory support through Yasmin, who invites her to Henry’s 40th birthday party, where Bevan meets Lord Alexander Norton, a newspaper proprietor concerned about legacy media’s declining influence under business minister Lisa Dearn. After Henry becomes Tender’s CEO, Yasmin lobbies Bevan to support Tender’s merger with an Austrian bank and its application for a UK banking license. At a regulatory meeting, the Prime Minister’s chief of staff pressures the Prudential Regulation Authority to approve the deal, citing press positioning Bevan as Labour’s new public face, and Bevan begins advocating for Tender. When Tender’s fraud is exposed, Yasmin attempts to shift blame onto the Labour government by persuading Bevan to confirm that Dearn suppressed an internal memo raising concerns about Tender; Bevan refuses. Yasmin circumvents her and runs the headline regardless, leading to Dearn’s resignation and prompting Bevan to rebuke Yasmin for lying and allowing Henry to take the fall.
=== Medicinal === In traditional Chinese medicine, the entirety of S. affinis is used as an agent to treat colds and pneumonia. In addition, root extract of S. affinis has shown antimicrobial activity. Furthermore, Baek et al. observed antioxidant activity in 2004. Also in 2004 inhibitory effects on acetylcholine esterase, monoamine oxidase and xanthine oxidase activities were observed in rat brains after 20 days of feeding with methanolic extracts of S. affinis. Ethanol extract from this plant also seems to have antitumour activity.
=== Nervous system impairment === The periods before and surrounding birth are typically normal in individuals with LNS. The most common presenting features are abnormally decreased muscle tone (hypotonia) and developmental delay, which are evident by three to six months of age. Affected individuals are late in sitting up, while most never crawl or walk. Irritability is most often noticed along with the first signs of nervous system impairment. Within the first few years of life, extrapyramidal involvement causes abnormal involuntary muscle contractions such as loss of motor control (dystonia), writhing motions (choreoathetosis), and arching of the spine (opisthotonus). Signs of pyramidal system involvement, including spasticity, overactive reflexes (hyperreflexia) and extensor plantar reflexes, also occur. The resemblance to athetoid cerebral palsy is apparent in the neurologic aspects of LNS. As a result, most individuals are initially diagnosed as having cerebral palsy. The motor disability is so extensive that most individuals never walk, and become lifelong wheelchair users.
Sources: en.wikipedia.org
"Catholic conservatives in the Weimar Republic: the politics of the Rhenish-Westphalian aristocracy, 1918–1933." German History 18.1 (2000): 60-85. Kohler, Eric D. "The Successful German Center-Left: Joseph Hess and the Prussian Center Party, 1908–32." Central European History 23.4 (1990): 313-348. Lutz, Ralph Haswell. "The Collapse of German Democracy under the Brüning Government March 30, 1930–May 30, 1932." Pacific Historical Review (1941) 10#1: 1-14. online Ross, Ronald J. "Critic of the Bismarckian Constitution: Ludwig Windthorst and the Relationship Between Church and State in Imperial Germany," Journal of Church & State (1979) 21#3 pp 483–506. online Ross, Ronald J. Beleaguered Tower: The Dilemma of Political Catholicism in Wilhelmine Germany (1976), Zeender, John. "Ludwig Windthorst, 1812-1891," History (1992) 77#290 pp 237–54 online Zeender, John K. "The German Center Party, 1890-1906." Transactions of the American Philosophical Society (1976) 66#1 pp 1–125.
Observations in vitro and of tumours extracted from those five patients suggest that DCA might act against cancer cells by depolarising abnormal mitochondria found in glioblastoma cancer cells – allowing the mitochondria to induce apoptosis (cell death) of the malignant cells. In vitro work with DCA on neuroblastomas (which have fewer recognised mitochondrial abnormalities) showed activity against malignant, undifferentiated cells. A 2016 case report discussed and reviewed the application of DCA in central nervous system malignancies. A 2018 study found that DCA could trigger a metabolic switch from glycolysis (the Warburg effect) to mitochondrial OXPHOS and increase reactive oxygen stress affecting tumor cells. These effects were not observed in non-tumor cells. Current research has focused mainly on combining DCA with other cancer drugs to form prodrug complexes which can release both agents in a more targeted manner.
== Occurrence == Chymosin is found in a wide range of tetrapods, although it is best known to be produced by ruminant animals in the lining of the abomasum. Chymosin is produced by gastric chief cells in newborn mammals to curdle the milk they ingest, allowing a longer residence in the bowels and better absorption. Non-ruminant species that produce chymosin include pigs, cats, seals, and chicks. One study reported finding a chymosin-like enzyme in some human infants, but others have failed to replicate this finding. Humans have a pseudogene for chymosin that does not generate a protein, found on chromosome 1. Humans have other proteins to digest milk, such as pepsin and lipase. In addition to the primate lineage leading up to humans, some other mammals have also lost the chymosin gene.
On the campaign trail, Talarico often tells a story from when he was a middle school teacher about a student who was kicked out of fifth grade for bringing a knife to school and threatening his teacher. Talarico later had the boy as a student and said that his behavior improved before he got into a fight and was kicked out of school again. Talarico blamed the events on the Texas legislature cutting public school funding, which he said led to the school's therapist being laid off. Since Talarico won the nomination, his campaign has been noted for its record-breaking fundraising. In the first quarter of 2026, it raised over $27 million, more than any Senate campaign ever for that period, and more than double the totals raised by the two previous Democratic nominees' campaigns in Texas during the same period, with Colin Allred raising $9.5 million in the first quarter of 2024, and Beto O'Rourke raising $6.7 million in 2018.
Most SDS-PAGE protein separations are performed using a "discontinuous" (or DISC) buffer system that significantly enhances the sharpness of the bands within the gel. During electrophoresis in a discontinuous gel system, an ion gradient is formed in the early stage of electrophoresis that causes all of the proteins to focus on a single sharp band in a process called isotachophoresis. Separation of the proteins by size is achieved in the lower, "resolving" region of the gel. The resolving gel typically has a much smaller pore size, which leads to a sieving effect that now determines the electrophoretic mobility of the proteins.
Sources: en.wikipedia.org
No. Thymosin beta-4 is a 43-residue protein, while TB-500 refers to a seven-residue fragment corresponding to its N-terminal region. The two names are often used loosely in commercial and community writing, which obscures the difference in size, sequence, and likely behavior.
The fragment contains an actin-binding motif, and cell-free experiments show that it can interact with monomeric actin. That observation is the basis for interest in cell migration and repair processes. Effects reported in animals are not established for humans.
Purity is usually stated by the supplier rather than fixed by a pharmacopoeial monograph, and typical listings report a percentage from reverse-phase HPLC. Independent verification is uncommon. Because no single accepted specification exists, comparisons between lots and between suppliers are difficult.
The lyophilised powder is typically held at -20 C or lower in a dry, dark place. Reconstituted solutions are aliquoted and frozen to avoid repeated freeze-thaw cycles.