Everything below concerns reconstitution. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2025-12-27. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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 |
|---|---|---|
| Molecular formula | C38H68N10O14 | Calculated for the acetylated heptapeptide |
| Molecular weight | ~889 Da | Monoisotopic mass approximately 889.0 Da |
| Amino acid sequence | Ac-LKKTETQ | N-terminal acetylated seven-residue peptide |
| Appearance | White to off-white powder | Typically supplied as a lyophilized solid |
| Solubility class | Water-soluble | Peptides of this size generally dissolve in aqueous media |
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.
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.
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.
Proposed activity centers on actin sequestration and on the movement of cells during repair processes. In cell culture and animal models, the fragment has been associated with migration, tube formation, and tissue remodeling. These observations are frequently described as preliminary, because most published work uses rodent or in vitro systems rather than controlled human trials. Whether the short fragment reproduces the effects of the full protein remains an open question, and the relationship between dose, route, and measured outcome is not well characterized.
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.
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.
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.
== Career and research == Her first position was at the Allan Memorial Institute of Psychiatry (associated with McGill University). In 1952, she joined the staff of the National Institute for Medical Research (NIMR) where she served as head of the division of Immunology from 1976 to 1988. During that time, she worked extensively with fellow immunologist John H. Humphrey to establish the immunology divisions. Askonas focused on B cells and determined their role in producing antibodies as part of the immune response. At the NIMR she began researching the biosynthesis of polypeptides in milk proteins discovering that the peptides were synthesised from amino acids rapidly in one piece. From 1955 to 1959 she studied the sites of antibody formation using radioactivity to develop our understanding of antibody molecules and the cells of the immune system. From 1959 to 1961 she studied plasma cell tumors as models for antibody formation. She went on to investigate macrophages and their role in antigen presentation (1962–1968). From 1963 to 1966 she studied the fate of antigen in relation to antibody formation and later continued her study of B cells from 1965 to 1970. She wrote several biographies of high-profile scientists, including Niels Kaj Jerne, César Milstein and John Herbert Humphrey. Askonas conducted a filmed interview with Stanley Peart as a segment of what became the Medical Sciences Video Archive housed in the special collections of the library at Oxford Brookes University.
=== Visual Effects === The Lord of the Rings: The Fellowship of the Ring (2001) (lead massive crowd technical director) The Lord of the Rings: The Two Towers (2002) (senior massive technical director) The Matrix Reloaded (2003) (lead technical director) The Matrix Revolutions (2003) (sentinel/swarm lead) The Lord of the Rings: The Return of the King (2003) (senior massive technical director) Catwoman (2004) (CG supervisor) Drawing Restraint 9 (2005) (lead technical director) Pirates of the Caribbean: Dead Man's Chest (2006) (digital artist)
Diagnosis of ILD involves assessing the signs and symptoms as well as a detailed history investigating occupational exposures. ILD usually presents with dyspnea, worsening exercise tolerance and 30-50% of those with ILD have a chronic cough. On examination, velcro crackles, in which the crackles compare to the sound of velcro being unfastened, are common in ILD. Pulmonary function tests usually show a restrictive defect with decreased diffusion capacity of carbon monoxide (DLCO) indicating reduced alveolar to blood capillary transport. Pulmonary function testing is indicated for all people with ILD and the FVC loss and DLCO is prognostic, with an FVC loss of greater than 5% per year associated with a poor prognosis in fibrosis subtypes of ILD. A chest x-ray is 63% sensitive and 93% specific for ILD. With advances in computed tomography, CT scans of the chest have supplanted lung biopsy as the preferred diagnostic test for ILD. A thoracic CT scan is 91% sensitive and 71% specific for ILD. In higher income countries, less than 10% of people with ILD undergo a lung biopsy as part of the diagnostic evaluation. A lung biopsy may be required if the clinical history and imaging are not clearly suggestive of a specific diagnosis or malignancy cannot otherwise be ruled out. Surgical lung biopsy or via a video-assisted thoracoscopic surgery (VATS) biopsy is associated with a mortality rate up to 1-2%.
== Chemistry == Amino acid sequence: Asp-Cys-Val-Arg-Phe-Trp-Gly-Lys-Cys-Ser-Gln-Thr-Ser-Asp-Cys-Cys-Pro-His-Leu-Ala-Cys-Lys-Ser-Lys-Trp-Pro-Arg-Asn-Ile-Cys-Val-Trp-Asp-Gly-Ser-Val Molecular formula: C177H268N52O50S6 ω-Grammotoxin SIA can be purified from Grammostola rosea venom by reverse phase high performance liquid chromatography.
Penis or pizzle is a type of offal. In many cultures, it is a taboo food. Penis is eaten in some cultures or traditional medicine systems as a purported health food: it may be seen as an aphrodisiac, a cure for sexual dysfunction, a hangover cure, and more. Penis is often paired with testicles as food.
Sources: en.wikipedia.org
=== Early student activism: 1966–1968 === Biko was initially interested in studying law at university, but many of those around him discouraged this, believing that law was too closely intertwined with political activism. Instead they convinced him to choose medicine, a subject thought to have better career prospects. He secured a scholarship, and in 1966 entered the University of Natal Medical School. There, he joined what his biographer Xolela Mangcu called "a peculiarly sophisticated and cosmopolitan group of students" from across South Africa; many of them later held prominent roles in the post-apartheid era. The late 1960s was the heyday of radical student politics across the world, as reflected in the protests of 1968, and Biko was eager to involve himself in this environment. Soon after he arrived at the university, he was elected to the Students' Representative Council (SRC). The university's SRC was affiliated with the National Union of South African Students (NUSAS). NUSAS had taken pains to cultivate a multi-racial membership but remained white-dominated because the majority of South Africa's students were from the country's white minority. As Clive Nettleton, a white NUSAS leader, put it: "the essence of the matter is that NUSAS was founded on white initiative, is financed by white money and reflects the opinions of the majority of its members who are white". NUSAS officially opposed apartheid, but it moderated its opposition in order to maintain the support of conservative white students.
These candidates are expected to be useful in the treatment of prostate cancer. The active ingredient in G-202 is a chemotherapeutic agent derived from thapsigargin, a plant-based cytotoxin that kills by disrupting the calcium balance in cancer cells. GenSpera's prodrug delivery system keeps the thapsigargin inactive in the body until it finds cells that it has been programmed to seek. Once those cells in the body are found, the prodrug releases its active ingredient and destroys all of the targeted cells. The National Cancer Institute had previously demonstrated that thaspigargin was ten-to-a-hundredfold more potent than traditional chemotherapeutic agents in killing all types of cells. Thapsigargin kills cells irrespective of the rate of cell division, which may provide an effective approach to kill both fast- and slow-growing cancers as well as cancer stem cells.
Lendemeriella aureopruinosa is a species of crustose lichen in the family Teloschistaceae. Found in the Russian Far East, it was formally described as a new species in 2021 by Ivan Frolov, Jan Vondrák, Ulf Arup, Liudmila Konoreva, and Sergey Chesnokov, Lidia Yakovchenko, and Evgeny Davydov. The type specimen was collected on the banks of River Bes-Yuryakh (Yllymakh, Republic of Sakha); here it was found growing on siliceous outcrops in a forest comprising largely birch, alder, and larch trees. The thallus of the lichen ranges in form from an inconspicuous grey film to a more well-developed crust or areoles. Its apothecia measure 0.3–0.6 mm in diameter and have a dark-orange to brick-red coloured disc. Secondary chemicals detected in the lichen (using high-performance liquid chromatography) include parietin, parietinic acid, emodin, teloschistin, and fallacinal. The specific epithet aureopruinosa refers to the bright gold-coloured pruina that is found on young apothecia.
If the acyl CoA contains a cis-Δ3 bond, then cis-Δ3-Enoyl CoA isomerase will convert the bond to a trans-Δ2 bond, which is a regular substrate. If the acyl CoA contains a cis-Δ4 double bond, then its dehydrogenation yields a 2,4-dienoyl intermediate, which is not a substrate for enoyl CoA hydratase. However, the enzyme 2,4 Dienoyl CoA reductase reduces the intermediate, using NADPH, into trans-Δ3-enoyl CoA. This compound is converted into a suitable intermediate by 3,2-Enoyl CoA isomerase and β-Oxidation continues.
A 1998 estimate suggested that the total annual worldwide consumption of Boletus edulis and closely related species (B. aereus, B. pinophilus, and B. reticulatus) was between 20,000 and 100,000 tons. Approximately 2,700 tonnes (3,000 tons) were sold in France, Italy and Germany in 1988, according to official figures. The true amount consumed far exceeds this, as the official sales figures did not account for informal sales or consumption by collectors. They are widely exported and sold in dried form, reaching countries where they do not occur naturally, such as Australia and New Zealand. The autonomous community of Castile and León in Spain produces 7,700 tonnes (8,500 tons) annually. In autumn, the price of porcini in the Northern Hemisphere typically ranges between $20 and $80 per kilogram, although in New York in 1997 the wholesale price rose to more than $200 per kilogram due to scarcity. In the vicinity of Borgotaro in the Province of Parma of northern Italy, the four species Boletus edulis, B. aereus, B. aestivalis and B. pinophilus have been recognised for their superior taste and officially termed Fungo di Borgotaro. Here these mushrooms have been collected for centuries and exported commercially. Owing to the globalisation of the mushroom trade most of the porcini commercially available in Italy or exported by Italy no longer originate there. Porcini and other mushrooms are also imported into Italy from various locations, especially China and eastern European countries; these are then often re-exported under the "Italian porcini" label.
Sources: en.wikipedia.org
TB-500 is a synthetic heptapeptide corresponding to a fragment of thymosin beta-4. It is used in laboratory research and is not an approved drug.
No. Thymosin beta-4 is a 43-amino-acid protein, while TB-500 represents only a short N-terminal segment. The two should not be treated as interchangeable in experimental design.
It is often called a thymosin beta-4 fragment, Tβ4 fragment, or Ac-LKKTETQ. The name TB-500 is mainly a commercial or catalog label rather than a formal chemical name.
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.