The short version of lyophilised powder fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-05-06 and is reviewed periodically as new material appears.
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.
Reconstitution of a lyophilized peptide is normally done with sterile water or a suitable buffer under aseptic conditions. Adding solvent down the vial wall and allowing gentle dissolution instead of vigorous vortexing reduces the chance of aggregation, which can lower the effective concentration of the resulting solution. Concentrated stocks are usually diluted into working buffer shortly before use. Because no standard preparation protocol exists for TB-500 specifically, laboratories adapt general peptide handling practice, and reported results may reflect differing preparation choices.
| 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 |
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.
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.
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.
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.
The regulatory position is broadly consistent across major jurisdictions: no thymosin beta-4 fragment is an approved medicine, and laboratory material is commonly labelled as not intended for human consumption. Anti-doping rules in sport list thymosin beta-4 and its fragments among prohibited peptide hormones. Because these products travel through research-chemical channels rather than pharmaceutical supply chains, quality varies considerably between vendors. Independent testing of identity, purity and sterility is the only dependable check, and a certificate of analysis describes one batch rather than a supplier's whole catalogue.
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.
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.
Detection in biological matrices generally relies on liquid chromatography coupled with tandem mass spectrometry, because the peptide lacks a convenient ultraviolet chromophore beyond the amide backbone. Immunoassays have been described, but antibodies raised against the fragment can cross-react with the full-length protein or with unrelated peptides, so findings usually require confirmation by a second technique. Sample preparation typically involves protein precipitation followed by solid-phase extraction. Reported detection windows depend on dose, route, matrix, and instrument sensitivity.
Produced by Mike Tomlinson, made by Orlando Television Productions with WGBH 21 October The Mind Benders, in May 1991, the Broadcasting Complaints Commission, ruled that this episode should have been broadcast under the title Open Mind; about the Hemi-Sync method; the Float Centre, in St John's Wood with Samantha O'Connor, which cost £22 an hour; Peter Fenwick and flotation tanks; the EEG Mind Mirror of Geoffrey Blundell; the voice of Robert Monroe, and a hemi-sync session in Cambridge, where 200hz is played in one ear, and 206hz in the other ear; a so-called mind gymnasium in Japan, launched in 1975; Australian psychologist Dorothy Rowe, who questioned the veracity of the methods, which could be explained through the placebo effect, which is often not an unimportant effect on health. Narrated by Peter Jones, produced by Patrick Uden, directed by Gary Burczak, made by Uden Associates. Much of the techniques demonstrated were not dissimilar to techniques advocated by the 1990s Natural Law Party 28 October The Winning Streak, about East German methods in women athletics; with Katrin Krabbe. Narrated by Tony Ward, produced by Mike Johnstone, directed by Nikolas L.
== Evolution of neuropeptide signaling == Peptides are ancient signaling systems that are found in almost all animals on Earth. Genome sequencing reveals evidence of neuropeptide genes in Cnidaria, Ctenophora, and Placozoa, some of the oldest living animals with nervous systems or neural-like tissues. Recent studies also show genomic evidence of neuropeptide processing machinery in metazoans and choanoflagellates, suggesting that neuropeptide signaling may predate the development of nervous tissues. Additionally, Ctenophore and Placozoa neural signaling is entirely peptidergic and lacks the major amine neurotransmitters such as acetylcholine, dopamine, and serotonin. This also suggests that neuropeptide signaling developed before amine neurotransmitters.
== Veterinary uses == In the US, clomipramine is only licensed to treat separation anxiety in dogs for which it is sold under the brand name Clomicalm. It has proven effective in the treatment of obsessive–compulsive disorders in cats and dogs. In dogs, it has also demonstrated similar efficacy to fluoxetine in treating tail chasing. In dogs some evidence suggests its efficacy in treating noise phobia. Clomipramine has also demonstrated efficacy in treating urine spraying in cats. Various studies have been done on the effects of clomipramine on cats to reduce urine spraying/marking behavior. It has been shown to be able to reduce this behavior by up to 75% in a trial period of four weeks. Clomipramine has the side effect of inhibiting thyroid peroxidase and inhibiting the uptake of iodide.
=== Precautions === Precaution is needed when taken in individuals with tetracycline hypersensitivity, pregnant women, and children. It has been found to cause fetal harm when administered during pregnancy and therefore is classified as pregnancy category D. In rats or rabbits, tigecycline crossed the placenta and was found in the fetal tissues, and is associated with slightly lower birth weights as well as slower bone ossification. Even though it was not considered teratogenic, tigecycline should be avoided unless benefits outweigh the risks. In addition, its use during childhood can cause yellow-grey-brown discoloration of the teeth and should not be used unless necessary. More so, there are clinical reports of tigecycline-induced acute pancreatitis, with particular relevance to patients also diagnosed with cystic fibrosis. Tigecycline showed an increased mortality in patients treated for hospital-acquired pneumonia, especially ventilator-associated pneumonia (a non-approved use), but also in patients with complicated skin and skin structure infections, complicated intra-abdominal infections and diabetic foot infection. Increased mortality was in comparison to other treatment of the same types of infections. The difference was not statistically significant for any type, but mortality was numerically greater for every infection type with Tigecycline treatment, and thus prompted a black box warning by the FDA.
Sources: en.wikipedia.org
Plants can synthesise coloured dyes and pigments such as the anthocyanins responsible for the red colour of red wine, yellow weld and blue woad used together to produce Lincoln green, indoxyl, source of the blue dye indigo traditionally used to dye denim and the artist's pigments gamboge and rose madder. Sugar, starch, cotton, linen, hemp, some types of rope, wood and particle boards, papyrus and paper, vegetable oils, wax, and natural rubber are examples of commercially important materials made from plant tissues or their secondary products. Charcoal, a pure form of carbon made by pyrolysis of wood, has a long history as a metal-smelting fuel, as a filter material and adsorbent and as an artist's material and is one of the three ingredients of gunpowder. Cellulose, the world's most abundant organic polymer, can be converted into energy, fuels, materials and chemical feedstock. Products made from cellulose include rayon and cellophane, wallpaper paste, biobutanol and gun cotton. Sugarcane, rapeseed and soy are some of the plants with a highly fermentable sugar or oil content that are used as sources of biofuels, important alternatives to fossil fuels, such as biodiesel. Sweetgrass was used by Native Americans to ward off bugs like mosquitoes. These bug repelling properties of sweetgrass were later found by the American Chemical Society in the molecules phytol and coumarin.
== Bibliography == Bonagura J., DVM; et al. (2000). Current Veterinary Therapy. Vol. 13. pp. 321–381. Cossar, Harper (2011). Letterboxed: The Evolution of Widescreen Cinema. University Press of Kentucky. ISBN 978-0-813-12651-7. Halliwell, Martin (2013). Therapeutic Revolutions: Medicine, Psychiatry, and American Culture, 1945-1970. Rutgers University Press. ISBN 978-0-813-56066-3. Ingle DJ (October 1950). "The biologic properties of cortisone: a review". J. Clin. Endocrinol. Metab. 10 (10): 1312–54. doi:10.1210/jcem-10-10-1312. PMID 14794756. Woodward R. B.; Sondheimer F.; Taub D. (1951). "The Total Synthesis of Cortisone". Journal of the American Chemical Society. 73 (8): 4057. Bibcode:1951JAChS..73.4057W. doi:10.1021/ja01152a551.
== Computer-aided drug design == The most fundamental goal in drug design is to predict whether a given molecule will bind to a target and if so how strongly. Molecular mechanics or molecular dynamics is most often used to estimate the strength of the intermolecular interaction between the small molecule and its biological target. These methods are also used to predict the conformation of the small molecule and to model conformational changes in the target that may occur when the small molecule binds to it. Semi-empirical, ab initio quantum chemistry methods, or density functional theory are often used to provide optimized parameters for the molecular mechanics calculations and also provide an estimate of the electronic properties (electrostatic potential, polarizability, etc.) of the drug candidate that will influence binding affinity. Molecular mechanics methods may also be used to provide semi-quantitative prediction of the binding affinity. Also, knowledge-based scoring function may be used to provide binding affinity estimates. These methods use linear regression, machine learning, neural nets or other statistical techniques to derive predictive binding affinity equations by fitting experimental affinities to computationally derived interaction energies between the small molecule and the target. Ideally, the computational method will be able to predict affinity before a compound is synthesized and hence in theory only one compound needs to be synthesized, saving enormous time and cost.
== See also == GADV-protein world hypothesis The Major Transitions in Evolution RNA-based evolution Protocell or Pre-cell, the primordial version of a cell which confined RNA and later, DNA First universal common ancestor (FUCA) Origin of DNA
In real-world settings, a review of more than 40,000 patient records found that while methadone and buprenorphine reduced risk of fatal overdose, naltrexone administration showed no greater effect on overdose or subsequent emergency care than counseling alone. Despite these findings, naltrexone's manufacturer and some health authorities have promoted the medicine as superior to methadone and buprenorphine since it is not an opioid and does not induce dependence. The manufacturer has also marketed directly to law enforcement and criminal justice officials, spending millions of dollars on lobbying and providing thousands of free doses to jails and prisons. The technique has been successful, with the criminal justice system in 43 states now incorporating long-acting naltrexone. Many do this through Vivitrol courts that offer only this option, leading some to characterize this as "an offer that cannot be refused." The company's marketing techniques have led to a Congressional investigation, and warning from the FDA about failure to adequately state risks of fatal overdose to patients receiving the medicine. In May 2017, United States Secretary of Health and Human Services Tom Price praised [Vivitrol] as the future of opioid addiction treatment after visiting the company's plant in Ohio. His remarks set off sharp criticism with almost 700 experts in the field of substance use submitting a letter to Price cautioning him about Vivitrol's "marketing tactics" and warning him that his comments "ignore widely accepted science".
Sources: en.wikipedia.org
Amino acid score is used to determine if a protein is complete. It is used along with the measure of protein digestibility that refers to how well a given protein is digested, to compare the proportion of essential amino acids found in one protein to the proportion in a "reference protein" considered to be complete.
== Diagnosis == Heart disease is often undiagnosed until a serious problem occurs, such as heart attack or cardiac arrest. Regular checkups can lead to an early diagnosis and preventative treatment. Screening tests and risk assessments should begin around age 20 if one does not have any risk factors. Screenings should begin in childhood if one has risk factors such as obesity, sedentary lifestyle, or a family history of heart conditions. Healthcare providers will run blood tests to check for cholesterol, triglycerides, lipoproteins, sugar, or proteins that are a sign of inflammation.
== Naturally occurring molecular knots == Organic molecules containing knots may fall into the categories of slipknots or pseudo-knots. They are not considered mathematical knots because they are not a closed curve, but rather a knot that exists within an otherwise linear chain, with termini at each end. Knotted proteins are thought to form molecular knots during their tertiary structure folding process, and knotted nucleic acids generally form molecular knots during genomic replication and transcription, though details of knotting mechanism continue to be disputed and ambiguous. Molecular simulations are fundamental to the research on molecular knotting mechanisms. Knotted DNA was found first in single-stranded, circular, bacterial DNA, though double-stranded circular DNA has been found to also form knots. Naturally knotted RNA has not yet been reported. A number of proteins containing naturally occurring molecular knots have been identified. The knot types found to be naturally occurring in proteins are the
On 21 July 2011, following the exclusion of the original Salernitana club, Salerno mayor Vincenzo De Luca, in compliance with Article 52 of N.O.I.F., assigned the new title to Marco Mezzaroma, brother-in-law of Lazio owner and chairman Claudio Lotito. The new club was admitted to Serie D under the denomination of Salerno Calcio. In the 2011–12 season, Salernitana was immediately promoted to Lega Pro Seconda Divisione after winning Group G of Serie D. On 12 July 2012, the club was renamed US Salernitana 1919. In the 2012–13 Lega Pro Seconda Divisione season, Salernitana finished first in Girone B, and was promoted to Lega Pro Prima Divisione. This was the second consecutive promotion for the team. Finally Salernitana won Group C of Lega Pro and returned Serie B in 2014–15 season. After several seasons at Serie B level, Salernitana won promotion to Serie A at the end of the 2020–21 Serie B season under the tenure of head coach Fabrizio Castori, finishing in 2nd place behind champions Empoli. Promotion was secured with a 3–0 victory over Pescara on the final matchday. Salernitana's return to Serie A however required Lotito and Mezzaroma to sell the club, due to Italian football laws not allowing two clubs from the same owner to play in the same league. On 7 July 2021, the FIGC Federal Council approved the trust of Salernitana to take control of the club, meaning it was officially enrolled in Serie A for the first time in 23 years.
Irregular menstrual pattern: irregular bleeding and spotting is common in the first three to six months of use. After that time periods become shorter and lighter, and 20% of women stop having periods after one year of use. The average user reports 16 days of bleeding or spotting in the first month of use, but this diminishes to about four days at 12 months. Cramping and pain: many women feel discomfort or pain during and immediately after insertion. Some women may have cramping for the first 1–2 weeks after insertion. Expulsion: Sometimes the IUD can slip out of the uterus. This is termed expulsion. Around 5% of IUD users experience expulsion. If this happens a woman is not protected from pregnancy. Expulsion is more common in younger women, women who have not had children, and when an IUD is inserted immediately after childbirth or abortion. Perforation: Very rarely, the IUD can be pushed through the wall of the uterus during insertion. Risk of perforation is mostly determined by the skill of the practitioner performing the insertion. For experienced medical practitioners, the risk of perforation is one per 1,000 insertions or less. With postpartum insertions, perforation of the uterus is more likely to occur when uterine involution is incomplete; involution usually completes by 4–6 weeks postpartum. Special considerations apply to women who plan to breastfeed. If perforation does occur it can damage the internal organs, and in some cases surgery is needed to remove the IUD.
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.