If you have been reading about thymosin beta-4 and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2026-06-20. Numbers and descriptions here follow the published literature rather than marketing material.
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.
Lyophilised peptide is normally reconstituted with sterile water or a neutral buffer shortly before use. Because repeated freeze-thaw cycles can degrade the material, dividing a reconstituted solution into single-use aliquots is a common practice. Working solutions are usually kept cold and protected from light. The exact shelf life depends on concentration, buffer composition, and handling, so it is often determined empirically rather than assumed.
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.
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.
The designation TB-500 circulates in laboratory and catalog contexts without a single agreed definition. Most product listings apply it to an N-terminally acetylated seven-residue fragment of thymosin beta-4, while other listings attach the same label to the full 43-residue protein. Because the term is commercial rather than systematic, two entries bearing identical names may describe different molecules. Any documentation should therefore state which sequence a given sample is claimed to contain.
| Property | Value | Notes |
|---|---|---|
| Purity determination | Reversed-phase HPLC | UV detection commonly at 214 nm |
| Mass confirmation | Mass spectrometry | Compared against theoretical 888.5 Da |
| Powder storage | -20 C or below | Dry and protected from light |
| Reconstituted storage | Aliquoted and frozen | Avoid repeated freeze-thaw cycles |
| Reconstitution solvent | Sterile water or neutral buffer | Avoid extreme pH conditions |
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.
Full-length thymosin beta-4 consists of roughly forty-three amino acids and ranks among the more abundant small proteins in the cytoplasm. The fragment is much shorter, so it cannot reproduce every function attributed to the intact molecule. In cell culture, short actin-binding motifs can interfere with filament dynamics and cell movement, but such observations come from controlled experiments rather than from whole-animal work. Whether a truncated fragment produces the same effects as the parent protein remains an open question.
Interest in the peptide grew during the 2000s and 2010s, when studies of tendon and ligament injuries in horses reported changes in lesion size after treatment. Those reports circulated widely outside the scientific literature and shaped much of the current online discussion. Subsequent reviews noted inconsistent study design, small groups, and a shortage of independent replication. Popular descriptions often blur the line between the fragment, the complete protein, and unrelated growth factors, which complicates comparisons across sources.
Lyophilised peptide powders are hygroscopic, and the fragment absorbs atmospheric moisture when a vial is opened at room temperature. Weighing and aliquoting are normally done quickly in a dry environment, and stock solutions are divided into single-use portions before freezing. Repeated freeze-thaw cycles are avoided because they promote aggregation and can shift the measured content of a vial. These practices are general to synthetic peptides rather than unique to this sequence, but they matter more for short chains kept for long periods.
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.
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.
== Use and effects == Noribogaine is the major active metabolite of the oneirogen ibogaine and is thought to be primarily though not exclusively responsible for its effects. In contrast to ibogaine, noribogaine has been limitedly evaluated in humans. It was noted in 2007 that administration of noribogaine to humans had not yet been reported. In 2015 and 2016 however, two clinical studies of noribogaine were published. It was tested at relatively low doses of 3 to 180 mg in these studies. At these doses, no hallucinations, dream-like states, or other hallucinogenic effects were reported. Similarly, it produced no μ-opioid receptor agonistic pharmacodynamic effects, such as pupil constriction or analgesia. At higher doses, in the area of 400 to 1,000 mg or more, ibogaine has been reported to produce hallucinogenic effects.
=== Digestibility-corrected AAS, DIAAS === DIAAS considers the profile of the essential amino acids that are actually absorbed. This value is calculated by estimating the amount of each EAA absorbed in the "test protein" by comparing how much of each EAA went into the mouth and how much was pumped out of the end of the small intestines. This was then turned into a profile Ai by dividing the amounts in milligrams of each EAA with the grams of the test protein eaten. From then on, the calculation is similar:
Acepromazine † — although it is mostly used in veterinary medicine. Chlorpromazine (Thorazine) Cyamemazine † Dixyrazine † Fluphenazine Levomepromazine‡ Mesoridazine (discontinued)† Perazine Pericyazine‡ Perphenazine Pipotiazine ‡ Prochlorperazine Promazine (discontinued) Promethazine Prothipendyl † Thioproperazine‡ (only English-speaking country it is available in is Canada) Thioridazine (discontinued) Trifluoperazine Triflupromazine (discontinued)†
It is typical to record spectrum of both the sample and a "reference". This step controls for a number of variables, e.g. infrared detector, which may affect the spectrum. The reference measurement makes it possible to eliminate the instrument influence. The appropriate "reference" depends on the measurement and its goal. The simplest reference measurement is to simply remove the sample (replacing it by air). However, sometimes a different reference is more useful. For example, if the sample is a dilute solute dissolved in water in a beaker, then a good reference measurement might be to measure pure water in the same beaker. Then the reference measurement would cancel out not only all the instrumental properties (like what light source is used), but also the light-absorbing and light-reflecting properties of the water and beaker, and the final result would just show the properties of the solute (at least approximately). A common way to compare to a reference is sequentially: first measure the reference, then replace the reference by the sample and measure the sample. This technique is not perfectly reliable; if the infrared lamp is a bit brighter during the reference measurement, then a bit dimmer during the sample measurement, the measurement will be distorted. More elaborate methods, such as a "two-beam" setup (see figure), can correct for these types of effects to give very accurate results. The Standard addition method can be used to statistically cancel these errors.
Sources: en.wikipedia.org
==== Francium ==== Francium is also predicted to show some differences due to its high atomic weight, causing its electrons to travel at considerable fractions of the speed of light and thus making relativistic effects more prominent. In contrast to the trend of decreasing electronegativities and ionisation energies of the alkali metals, francium's electronegativity and ionisation energy are predicted to be higher than caesium's due to the relativistic stabilisation of the 7s electrons; also, its atomic radius is expected to be abnormally low. Thus, contrary to expectation, caesium is the most reactive of the alkali metals, not francium. All known physical properties of francium also deviate from the clear trends going from lithium to caesium, such as the first ionisation energy, electron affinity, and anion polarisability, though due to the paucity of known data about francium many sources give extrapolated values, ignoring that relativistic effects make the trend from lithium to caesium become inapplicable at francium. Some of the few properties of francium that have been predicted taking relativity into account are the electron affinity (47.2 kJ/mol) and the enthalpy of dissociation of the Fr2 molecule (42.1 kJ/mol). The CsFr molecule is polarised as Cs+Fr−, showing that the 7s subshell of francium is much more strongly affected by relativistic effects than the 6s subshell of caesium.
=== Kits === The modern-day interest in absinthe has spawned a rash of absinthe kits from sellers claiming they produce homemade absinthe. Kits often call for soaking herbs in vodka or alcohol or adding a liquid concentrate to vodka or alcohol to create an ersatz absinthe. Such practices usually yield a harsh substance that bears little resemblance to the genuine article and is considered inauthentic by any practical standard. Some concoctions may even be dangerous, especially if they call for a potentially poisonous inclusion of herbs, oils, or extracts. In at least one documented case, a person suffered acute kidney injury after drinking 10 ml of pure wormwood oil.
=== Saprotrophic === Buna-shimeji (ブナシメジ, lit. beech shimeji), Hypsizygus tessulatus, also known in English as the brown beech or brown clamshell mushroom. Hypsizygus marmoreus is a synonym of Hypsizygus tessulatus. Cultivation of Buna-shimeji was first patented by Takara Shuzo Co., Ltd. in 1972 as hon-shimeji and the production started in 1973 in Japan. Now, several breeds are widely cultivated and sold fresh in markets. Bunapi-shimeji (ブナピー), known in English as the white beech or white clamshell mushroom. Bunapi was selected from UV-irradiated buna-shimeji ('hokuto #8' x 'hokuto #12') and the breed was registered as 'hokuto shiro #1' by Hokuto Corporation. Hatake-shimeji (ハタケシメジ), Lyophyllum decastes. Shirotamogidake (シロタモギダケ), Hypsizygus ulmarius. These two species had been also sold as hon-shimeji. Velvet pioppino (alias velvet pioppini, black poplar mushroom, Chinese: 茶樹菇/茶树菇), Agrocybe aegerita.
Inbreeding causes early death (inbreeding depression) in the zebra finch Taeniopygia guttata. Embryo survival (that is, hatching success of fertile eggs) was significantly lower for sib-sib mating pairs than for unrelated pairs. Darwin's finch Geospiza scandens experiences inbreeding depression (reduced survival of offspring) and the magnitude of this effect is influenced by environmental conditions such as low food availability.
The Corruption, Drug Trafficking and Other Serious Crimes (Confiscation of Benefits) Act (CDSA). This statute criminalises money laundering and imposes the requirement for persons to file suspicious transaction reports (STRs) and make a disclosure whenever physical currency or goods exceeding S$20,000 are carried into or out of Singapore. The Mutual Assistance in Criminal Matters Act (MACMA). This statute sets out the framework for mutual legal assistance in criminal matters. Legal instruments issued by regulatory agencies (such as the Monetary Authority of Singapore (MAS), in relation to financial institutions (FIs)) imposing requirements to conduct customer due diligence (CDD). The term 'money laundering' is not used as such within the CDSA. Part VI of the CDSA criminalises the laundering of proceeds generated by criminal conduct and drug tracking via the following offences:
Sources: en.wikipedia.org
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.
Mass spectrometry is the usual confirmatory method because it measures the intact mass. Reversed-phase chromatography is used alongside it to estimate purity.
Not directly. Reported percentages depend on the chromatographic method, detection wavelength, and integration criteria, so the underlying method details matter.
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.