The short version of TB-500 fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-07-19 and is reviewed periodically as new material appears.
Lyophilized TB-500 is hygroscopic and should be kept dry before use. The usual storage recommendation for the solid is -20 °C, protected from light and moisture. Once dissolved, the peptide is less stable, and repeated freeze-thaw cycles can promote aggregation or degradation. Laboratories often divide a reconstituted solution into single-use aliquots and store them at -80 °C. Exact stability limits depend on buffer, pH, and concentration, so published data do not define a single universal condition.
Identity and purity are checked with chromatographic and mass spectrometric methods. Reverse-phase high-performance liquid chromatography separates the peptide from related impurities, while mass spectrometry confirms the expected molecular mass. A certificate of analysis may report a purity percentage, but the laboratory should still verify the material independently. Common quality concerns include truncated sequences, deamidation, oxidation, and residual solvents from synthesis. Because TB-500 is short, some impurities can differ from the target by only a few mass units.
Reconstitution practices affect downstream measurements. The dry powder is typically dissolved in sterile water or a suitable aqueous buffer, then mixed gently rather than vortexed at high speed. Visible particles or cloudiness suggest incomplete dissolution or contamination and should be investigated. For long-term storage, aliquots should be labeled with concentration, solvent, and date. Open questions include how different buffers alter peptide conformation and whether specific container materials adsorb the peptide. Those variables can change apparent concentration in assays even when the chemical identity is correct.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Storage temperature (dry) | -20 °C | Protected from light and moisture |
| Storage temperature (solution) | -80 °C | Single-use aliquots recommended |
| Identity assay | LC-MS or MALDI-TOF | Confirms mass near 889 Da |
| Purity assay | RP-HPLC | Reports main peak percentage |
| Common impurities | Truncated peptides, deamidated forms | Arise from synthesis or storage |
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.
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.
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.
TB-500 is a shorthand label used in supplier catalogs and online discussion for a short synthetic peptide described as a fragment of thymosin beta-4. Most product listings present it as the N-terminally acetylated heptapeptide Ac-LKKTETQ, a sequence corresponding to the actin-binding region of the parent protein. The name is not a formal chemical designation and does not appear in standard nomenclature systems. Because labeling practices vary between vendors, two products sold under the same name may not contain the same molecule, and the stated sequence should be treated as a claim rather than a fixed definition.
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.
Alginic acid (E400), sodium alginate (E401), potassium alginate (E402), ammonium alginate (E403), calcium alginate (E404) - polysaccharides from brown algae Agar (E406, a polysaccharide obtained from red algae) Carrageenan (E407, a polysaccharide obtained from red seaweeds) Locust bean gum (E410, a natural gum polysaccharide from the seeds of the carob tree) Pectin (E440, a polysaccharide obtained from apple or citrus-fruit) Gelatin (E441, made by partial hydrolysis of animal collagen) Commercial jellies used in East Asian cuisines include the glucomannan polysaccharide gum used to make "lychee cups" from the konjac plants, and aiyu or ice jelly from the Ficus pumila climbing fig plant. Agar-agar produces a very clear gel with light residual taste. Gelatin sheets disperse easily with no residual taste, but powdered form may have some taste. Kappa carrageenan may include potassium chloride to improve the gelling process and produces a clear product with very little aftertaste. Iota carrageenan contains sodium chloride which improves gel formation. Sodium alginate produces a medium viscosity gel but may have some aftertaste. High-methoxy pectin is one of the most widely used gelling agents in food processing. It reacts with some sugars and acids and sometimes includes minerals to improve gelling process. Low-methoxy pectin reacts with calcium, and is used for the preparation of low sugar jams.
==== In children ==== The NICE Guideline recommends that SSRIs should not be used to treat depression in children and young people, except for fluoxetine, which may be considered for moderate to severe depression when psychological therapies alone are insufficient. In the United States, they are approved for use in pediatric patients; however, individuals under 25 years of age should be closely monitored for an increased risk of suicidality, as indicated by the FDA black box warning. SSRIs have the best outcomes when combined with cognitive-behavioral therapy. Their benefits are modest and tolerability varies. The benefits may be clinically unimportant and there are uncertain effects on suicide risk.
== Historian of Alltagsgeschichte in the Third Reich == Peukert was a leading expert in Alltagsgeschichte ("history of everyday life") and his work often examined the effect of Nazi social policies on ordinary Germans and on persecuted groups such as Jews and Roma. The subject of Alltagsgeschichte had first been established as a subject in the 1970s, and had first attracted attention when Martin Broszat and his protégés launched the "Bavaria project" in 1973, intended to document everyday life in Bavaria in the Third Reich. Broszat had begun the study of Alltagsgeschichte in the early 1970s with two goals. The first was to counter what Broszat considered to be the excessively "from above" high politics approach to writing about Nazi Germany which largely saw the story of the Third Reich by looking at the actions of Hitler and the rest of the Nazi elite and treating almost everybody else in Germany as merely passive objects controlled and manipulated by the state. Broszat wanted to treat the German people as subjects in their own lives during the Nazi era, making choices in their everyday lives, both for good and ill, albeit within a reduced range. The second goal of Broszat with Alltagsgeschichte was to end the "monumentalization" of the men involved in the 20 July plot in 1944, with Broszat complaining treated the story of resistance in Nazi Germany as one of few conservatives from the traditional elites in the aristocracy, the military, the bureaucracy, and the diplomatic corps struggling to overthrow the Nazi regime.
== Astronomy and spaceflight == There is no scientific evidence that the motion of stars, planets, and other celestial bodies influences the fates of humans, and astrology has repeatedly been shown to have no explanatory power in predicting future events. Astronauts in orbit have the sensation of being weightless because they are in free fall around the Earth, not because they are so far away from the Earth that its gravitational pull is negligible. For example, on the International Space Station the Earth's gravity is nearly 90% as strong as at the surface. Objects orbiting in space would not remain in orbit if not for the gravitational force, and gravitational fields extend infinitely, though the strength of the gravitational force is attenuated with distance. There is no limit to the distance across which two objects exert gravitational forces upon one another. The dark side of the Moon receives about the same amount of light from the Sun as the near side. Since the same side of the Moon always faces the Earth due to tidal locking, the far side had not been seen until Luna 3 photographed it in 1959. Hence, "dark" refers to the far side being unseen from Earth, not to any lack of illumination by the Sun. Black holes have the same gravitational effects as any other equal mass in their place. They will draw objects towards them according to distance and mass, just as any other celestial body does, except at very close distances to the black hole, comparable to its Schwarzschild radius.
Sources: en.wikipedia.org
== Awards and recognition == Pfizer has received various awards and recognitions related to its workplace policies and corporate practices. In the United States, Pfizer earned a 100% score from the Human Rights Campaign (2025) on the Corporate Equality Index for LGBTQ workplace equality and ranked highly in the Hispanic Association on Corporate Responsibility (2024) Corporate Inclusion Index. Pfizer was named a "Best Place to Work for Disability Inclusion" in the Disability Equality Index (2024) and received awards such as Top Diverse Employer, Top Hispanic Employer, and Top Disability-Friendly Company by DiversityComm, Inc. (2024). Other recognitions include being named one of "America's Greatest Workplaces" by Newsweek (2023), Clinical Trials Arena Excellence Awards 2023, inclusion in the top 10 of the "World's Most Admired Companies" by Fortune (2023), and being listed as a Top Employer for Diversity and Best Employer for Women by Forbes (2022). Pfizer was also recognized as a "Best Place to Work" by Glassdoor (2021) and a Top Employer by Science (2021) for its practices during the pandemic.
=== Possible uses === While gliotoxin exposure at high concentrations shows cytotoxic effects via a multitude of different pathways, low-dose gliotoxin has been shown to have beneficial biological functions. Low-dose gliotoxin can exert antioxidant activities in the presence of the thioredoxin redox system that can counter the release of ROS in cells as a result of the electron transport chain (ETC) during cellular respiration. Moderate doses of gliotoxin have also been found to exhibit an anti-inflammatory effect in vivo due to the suppression of NF-κB activity by gliotoxin. Doses of gliotoxin less than 40 nM can also activate latent HIV-1 gene expression, serving as a diagnostic of HIV infection. Gliotoxin can activate HIV-1 expression by targeting (LARP7), which results in the release of active P-TEFb and the positive regulation of transcription of HIV proteins. Treatment of 20 nM gliotoxin reversed HIV-1 latency without interfering in the activation of CD4+ or CD8+ T-cells that are involved in the elimination of HIV-infected cells. While research on this possible gliotoxin use is in early stages, this provides a possible future direction for HIV diagnosis and treatment.
=== Emerald Twilight and beyond === In Emerald Twilight, Hal Jordan is driven to insanity and becomes the villain Parallax following the destruction of his hometown Coast City. He attacks Boodikka, cuts off her right hand, and takes her power ring, leaving her for dead. Boodikka is later revealed to have survived, but has been placed in suspended animation by the Manhunters along with many other former Green Lanterns, with the Manhunters intending to harness their energy to create more advanced Manhunters. After being freed, Boodikka is shocked that she no longer has her hand, and appears to remember nothing past her encounter with Parallax. During a later confrontation with the Manhunters, Kreon is killed and his ring chooses Boodikka. She resumes her duties in the Green Lantern Corps, replacing her lost hand with a Lantern construct.
=== Naproxen and Cromolyn === Naproxen is a non-steroidal anti-inflammatory drug while cromolyn is an anti-allergic agent which acts as a mast cell stabilizer. Both drugs have demonstrated the anticancer effect in addition to hypoglycemic effect due to inhibition of glycogen synthase kinase-3β (GSK-3β). To validate the anti-GSK-3β hypothesis of naproxen and cromolyn, docking of the two structures against GSK-3β binding pocket and comparing their fitting with known GSK-3β inhibitor ARA014418 was performed, in addition to measuring the serum glucose, serum insulin, serum C-peptide, weight variation and hepatic glycogen levels for normal and diabetic fasting animal's models to assess their in vitro hypoglycemic effects. Naproxen and cromolyn were successfully docked into the binding site of GSK-3β (both were fitted into its binding pocket). They exhibited electrostatic, hydrophobic, and hydrogen-bonding interactions with key amino acids within the binding pocket with binding interaction profiles similar to AR-A014418 (the known inhibitor). The negative charges of the carboxylic acid groups in both drugs interact electrostatically with the positively charged guanidine group of Arg141. Moreover, the hydrogen bonding interactions between carboxylic acid moieties of cromolyn and the ammonium groups of Lys183 and Lys60, in addition to π-stacking of the naphthalene ring system of naproxen with the phenolic ring of Tyr134.
The main Imperial Russian Army was commanded by Field Marshal Michael Andreas Barclay de Tolly, who recognized that Napoleon's immediate goal was a decisive battle to crush the main Russian force in the west. In response, the Russian army used scorched-earth tactics as it withdrew east, and harried the Grande Armée with light Cossack cavalry. The Grande Armée did not adjust its operational methods in response. Provisioning such an enormous army with adequate food and fresh water had proven difficult since the very start of the campaign, exacerbated by the sparse terrain of western Russia; diseases such as typhus and dysentery rapidly became rampant among the rank and file. These factors led to most of the losses of the main column of the Grande Armée, which in one case amounted to 95,000 men, including deserters, in a week. The main Russian army retreated for almost three months. This constant retreat led to the increasing unpopularity of Barclay de Tolly (who was a Baltic German and already mistrusted by the Russian elite) and a respected Russian veteran, Prince Mikhail Kutuzov, was made the new Commander-in-Chief by Tsar Alexander. Finally, the two armies engaged in the Battle of Borodino on 7 September, in the vicinity of Moscow. The battle was the largest and bloodiest single-day action of the Napoleonic Wars, involving more than 250,000 men and resulting in at least 70,000 casualties. The battle was indecisive; the French captured the main positions on the battlefield but failed to destroy the Russian army.
Sources: en.wikipedia.org
The dry powder is normally kept at -20 °C, protected from light and moisture. Reconstituted solutions are often divided into aliquots and stored at -80 °C to reduce freeze-thaw damage.
Reverse-phase HPLC assesses purity, and mass spectrometry confirms molecular mass. The combination helps distinguish the target peptide from truncated or modified impurities.
Buffer composition, pH, adsorption to containers, and freeze-thaw history can all affect the amount of intact peptide in solution. These factors may change results even when the starting material is chemically correct.
Usually not, though usage overlaps. The label most often refers to a short acetylated fragment of the parent protein, while thymosin beta-4 itself is the full 43-residue molecule. Because suppliers vary, a sequence statement is needed to settle the question for any particular lot.