The short version of lyophilisation fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-04-03 and is reviewed periodically as new material appears.
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.
Several names appear in scientific and commercial contexts for this peptide. The label TB-500 is informal and does not follow standard biochemical nomenclature. Research articles more often describe the compound as a thymosin beta-4 fragment, Tβ4 fragment, or by its sequence Ac-LKKTETQ. Confusing TB-500 with full-length thymosin beta-4 can lead to incorrect assumptions about activity because the fragment lacks the remaining residues of the parent protein. The relationship between fragment and parent protein remains an active area of study.
The seven-residue chain carries several polar and charged side chains, so it dissolves readily in water and in aqueous buffers near neutral pH. No cysteine is present, so disulphide formation is not a concern and reducing agents are unnecessary. Dilute ammonium hydroxide or acetonitrile-water mixtures are sometimes used for stock solutions when initial dissolution is slow. Strongly alkaline conditions and prolonged contact with oxidising agents are avoided because they can modify lysine-containing stretches, and haze in solution usually signals incomplete dissolution or aggregated material.
Identity and purity are checked with reversed-phase high-performance liquid chromatography, which separates the target sequence from truncated or deletion analogues, and with mass spectrometry, which confirms the expected molecular mass. Amino acid analysis and peptide mapping give orthogonal confirmation but are used less often outside specialist laboratories. Counter-ion content varies: material purified on trifluoroacetic acid gradients retains trifluoroacetate, and ion exchange can convert the salt form. Residual water and solvent are measured by Karl Fischer titration or thermogravimetric analysis, and any purity figure should be read together with the method used to obtain it.
| 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 |
Controlled human trials of the short fragment are scarce. Much of what appears in review articles is extrapolated from animal models or from studies of the parent protein, and literature searches return a larger body of cardiac and ophthalmic work on thymosin beta-4 than on the abbreviated peptide. Regulatory treatment differs by jurisdiction, and in several countries the material is handled as a research chemical rather than an approved therapeutic. Statements about human benefit should be read as provisional.
Biological interest in this peptide centers on its relationship to actin dynamics. Thymosin beta-4 binds monomeric actin through an LKKTET motif, and a short sequence carrying that motif can compete with other actin-binding proteins in cell-free preparations. Investigators propose that such competition shifts the balance between filament assembly and disassembly, which in turn affects how readily a cell extends protrusions and migrates. Most of the supporting observations come from cultured cells and purified protein systems rather than from intact organisms.
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.
=== Identification === Mushroom Observer, a collaborative mushroom recording and identification project An Aid to Mushroom Identification Archived 26 July 2009 at the Wayback Machine, Simon's Rock College Online Edible Wild Mushroom Field Guide
== Cause == It is caused by autosomal recessive loss of function mutations in the GOSR2 gene, in chromosome 17. Most patients share the common mutation, specifically p.Gly144Trp. Rarely patients can present with congenital muscular dystrophy and PME at the same time.
In 2020, Schmitt was among 17 Republican attorneys general who joined Texas attorney general Ken Paxton in suing Georgia, Michigan, Wisconsin, and Pennsylvania to invalidate their electoral votes in the 2020 United States presidential election. The suit claimed the four states' presidential vote tallies were unconstitutional; no evidence supported these claims and the arguments had already been rejected in other state and federal courts. On December 11, 2020, the Supreme Court rejected the suit in an unsigned opinion.
== Further reading == Bishop, Michael; Duben-Engelkirk, Janet L., and Fody, Edward P. (1992). "Chapter 19, Liver Function, Clinical Chemistry Principles, Procedures, Correlations, 2nd Ed." Philadelphia, J.B. Lippincott Company. Miyabara, Yuichi; Tabata, Masako; Suzuki, Junzo; Suzuki, Shizuo (1992). "Separation and sensitive determination of i-urobilin and 1-stercobilin by high-performance liquid chromatography with fluorimetric detection". Journal of Chromatography B: Biomedical Sciences and Applications. 574 (2): 261–265. doi:10.1016/0378-4347(92)80038-R. PMID 1618958. Miyabara, Y.; Sakata, Y.; Suzuki, J.; Suzuki, S. (1994). "Estimation of faecal pollution based on the amounts of urobilins in urban rivers". Environmental Pollution. 84 (2): 117–122. doi:10.1016/0269-7491(94)90093-0. PMID 15091706. Munson-Ringsrud, Karen and Jorgenson-Linné, Jean (1995). "Urinalysis and Body Fluids, a ColorText and Atlas." St. Louis, Mosby. Nelson, L.; David, Cox M.M. (2005). “Chapter 22 – Biosynthesis of Amino Acids, Nucleotides, and Related Molecules”, pp. 856, In Lehninger Principles of Biochemistry. Freeman, New York. pp. 856. Voet, Donald; Voet, Judith G.; Pratt, Charlotte W. (2018-01-23). Voet's Principles of Biochemistry, Global Edition, 5th Edition. Wiley. p. 1200. ISBN 978-1-119-45166-2. Retrieved 2024-02-01.
Sources: en.wikipedia.org
==== Reaction with lipids ==== Hypochlorous acid reacts with unsaturated bonds in lipids, but not saturated bonds, and the ClO− ion does not participate in this reaction. This reaction occurs by hydrolysis with addition of chlorine to one of the carbons and a hydroxyl to the other. The resulting compound is a chlorohydrin. The polar chlorine disrupts lipid bilayers and could increase permeability. When chlorohydrin formation occurs in lipid bilayers of red blood cells, increased permeability occurs. Disruption could occur if enough chlorohydrin is formed. The addition of preformed chlorohydrin to red blood cells can affect permeability as well. Cholesterol chlorohydrin have also been observed, but do not greatly affect permeability, and it is believed that Cl2 is responsible for this reaction. Hypochlorous acid also reacts with a subclass of glycerophospholipids called plasmalogens, yielding chlorinated fatty aldehydes which are capable of protein modification and may play a role in inflammatory processes such as platelet aggregation and the formation of neutrophil extracellular traps.
The virus has been used for cyber warfare against the national oil companies Saudi Aramco and Qatar's RasGas. Saudi Aramco announced the attack on their Facebook page and went offline again until a company statement was issued on 25 August 2012. The statement falsely reported normal business was resumed on 25 August 2012. However a Middle Eastern journalist leaked photographs taken on 1 September 2012 showing kilometers of petrol trucks unable to be loaded due to backed business systems still inoperable. On 29 August 2012 the same attackers behind Shamoon posted another pastie on PasteBin.com, taunting Saudi Aramco with proof they still retained access to the company network. The post contained the username and password on security and network equipment and the new password for the CEO Khalid Al- Falih The attackers also referenced a portion of the Shamoon malware as further proof in the pastie. According to Kubecka, in order to restore operations. Saudi Aramco used its large private fleet of aircraft and available funds to purchase much of the world's hard drives, driving the price up. New hard drives were required as quickly as possible so oil prices were not affected by speculation. By 1 September 2012 gasoline resources were dwindling for the public of Saudi Arabia 17 days after the 15 August attack. RasGas was also affected by a different variant, crippling them in a similar manner.
Some manufacturers are also trying to improve on the traditional design by altering properties within these machines other than the pressure driving the sample through the orifice. One such example is Constant Systems, who have recently shown that their Cell Disruptors not only match the performance of a traditional French Press, but also that they are striving towards attaining the same results at a much lower power. Pressure Cycling Technology ("PCT"). PCT is a patented, enabling technology platform that uses alternating cycles of hydrostatic pressure between ambient and ultra-high levels (up to 90,000 psi) to safely, conveniently and reproducibly control the actions of molecules in biological samples, e.g., the rupture (lysis) of cells and tissues from human, animal, plant, and microbial sources, and the inactivation of pathogens. PCT-enhanced systems (instruments and consumables) address some challenging problems inherent in biological sample preparation. PCT advantages include: (a) extraction and recovery of more membrane proteins, (b) enhanced protein digestion, (c) differential lysis in a mixed sample base, (d) pathogen inactivation, (e) increased DNA detection, and (f) exquisite sample preparation process control. The Microfluidizer method used for cell disruption strongly influences the physicochemical properties of the lysed cell suspension, such as particle size, viscosity, protein yield and enzyme activity.
β-Carbolines and harmala alkaloids like harmine and harmaline contain DMT's close analogue NMT embedded in their structures. Triptans like sumatriptan, rizatriptan, eletriptan, almotriptan, frovatriptan, and zolmitriptan, which are antimigraine agents, all contain DMT in their structures. Similarly, the pertine antipsychotics including alpertine, milipertine, oxypertine, and solypertine are DMT derivatives. Bioisosteres of DMT in which the indole ring system has been replaced with a different ring system include isoDMT (an isoindole or isotryptamine), 2ZEDMA (an indolizine), and C-DMT (an indene), among others. The homologues of DMT in which the alkyl side chain has been shortened or lengthened by one carbon atom are gramine and dimethylhomotryptamine (DMHT), respectively. Further-extended homologues are also known. Deuterated isotopologues of DMT include deudimethyltryptamine (DMT-d10) or CYB004 (HLP004), SPL028 (D2-DMT; α,α-dideutero-DMT), and DMT-d4 (α,α,β,β-tetradeutero-DMT). Prodrugs of DMT such as 1-benzoyl-DMT and N-phosphonooxymethyl-DMT (N-POM-DMT) have also been described. Many of DMT's analogues and derivatives are serotonin receptor modulators and/or serotonergic psychedelics similarly to DMT itself.
Narrated by David Malone, produced by Simone Pilkington, directed by Tim Tate, made by Granada Television 21 December The Whale That Swam to London, an Equinox Special; it featured Rodney Coates of Seiche Underwater Acoustics, of Holsworthy in Devon, the former Professor of Acoustical Oceanography from 1990-96 at the University of Birmingham. Narrated by Dilly Barlow, produced by Nick Curwin, directed by Toby Macdonald, made by Firefly Film and Television Productions.
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.
Divide it into single-use aliquots and hold them frozen at -20 °C or below, protected from light. Repeated thawing of one container is the main avoidable source of variability.