Everything below concerns lyophilized powder. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-07-25. Numbers and descriptions here follow the published literature rather than marketing material.
Storage recommendations center on keeping the dry powder cold, dry, and dark. A freezer at -20 degrees Celsius or below is conventional, and desiccant is often included to limit moisture uptake. Once dissolved, the peptide is less stable, and solutions are typically kept frozen and thawed only once. Repeated freeze-thaw cycles are a common source of losses because they promote aggregation and adsorption to container surfaces. Working aliquots are therefore prepared in advance, and glass or low-binding plastic is usually preferred over ordinary laboratory plastic.
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.
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 |
|---|---|---|
| Appearance | White to off-white powder | Lyophilized cake or fluffy solid |
| Water solubility | High | Dissolves in water and neutral buffers |
| Dry storage | -20 °C or below | Dry, dark, desiccated |
| Reconstituted storage | Frozen, single thaw | Repeated freeze-thaw promotes loss |
| Purity method | Reverse-phase HPLC | Peak area read at 214 or 220 nm |
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.
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.
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.
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.
== Geschichte == Der erste Bericht über den Ort findet sich in der Chronica Boemorum des Cosmas von Prag, in welcher zu lesen ist, dass Herzog Vladislav I. im Jahre 1121 bei Bela eine deutsche Burg zerstören ließ. Bela war eine Siedlung der Choden an der Landesgrenze zum Nordgau (Bayern) und hatte bedeutende Privilegien als Grenzwächter. Seit dem 14. Jahrhundert erfolgte verstärkt der Zuzug deutschsprachiger Neusiedler und der Name Weißensulz entstand. Durch den Ort führt die Bahnlinie Domažlice (Taus)–Tachov (Tachau)–Planá u Mariánských Lázní (Plan bei Marienbad). Verwaltungstechnisch bildete Bělá nad Radbuzou (Weißensulz) ab der Mitte des 19. Jahrhunderts eine Gemeinde im Gerichtsbezirk Hostau bzw. im Bezirk Bischofteinitz. Im Jahre 1875 wurde die Gemeinde zum Marktflecken erhoben. Die über die Radbuza (Rabusa) führende untere Brücke ist eine Nachbildung der Prager Karlsbrücke mit Heiligenfiguren. 1839 hatte Weißensulz 175 Häuser mit 1449 Einwohnern. Die erste Gemeindevorsteherwahl fand im Jahre 1850 statt, wobei Andreas Martinka zum Gemeindeoberhaupt gewählt wurde. Unter ihm begann der sog. Waldprozess, der zwar in der ersten Instanz verlorenging, aber nach einer Audienz des Vorstehers Martinka bei Kaiser Franz Josef I. im Jahre 1867 wieder aufgenommen und 1870 gewonnen wurde. Er brachte der Gemeinde Weißensulz einen Genossenschaftswald im Ausmaß von 315 Joch bzw. 182 ha ein. Martinka erreichte auch, dass Weißensulz ein Postamt erhielt, und wurde dessen erster Postmeister. 1878 wurde die Volksschule dreiklassig.
1875 wurde die Gemeinde zum Markt erhoben und es konnten vier Jahrmärkte erkämpft werden. Zwischen 1892 und 1895 wurde das neue, fünfklassige Volksschulgebäude (Nr. 28) vollendet. Bělá nad Radbuzou (Weißensulz) gehörte bis zum Ende des Ersten Weltkriegs 1918 zum Königreich Böhmen als Teil Österreich-Ungarns. Nach dem Zerfall der Doppelmonarchie gehörte es zur Tschechoslowakei. Im Münchner Abkommen wurde der Ort dem Deutschen Reich zugeschlagen und gehörte bis 1945 zum Landkreis Bischofteinitz im sogenannten Sudetenland. Im Zweiten Weltkrieg verhinderte der Bürgermeister Ferdinand Wild eine Sprengung dieses Kulturdenkmals. Die Firmengruppe der Familien Wild, seit 1648 in Eisendorf und Weißensulz ansässig, ein Unternehmen für Stickerei- und Spitzenerzeugnisse zählte nach der Weltausstellung 1873 in Wien Fürsten- und Königshäuser zu ihren Kunden. Im Jahre 1945 wurde, auf der Basis der Beneš-Dekrete mit den deutschen Bewohnern des Ortes auch die Familie Wild enteignet und vertrieben. Im badischen Boxberg in Westdeutschland gelang ein Neuanfang der Produktion.
== Gemeindegliederung == Die Stadt Bělá nad Radbuzou (Weißensulz) besteht aus den Ortsteilen Bělá nad Radbuzou (Weißensulz), Bystřice (Wistersitz), Čečín (Zetschin), Černá Hora (Tschernahora), Doubravka (Dobraken), Hleďsebe (Siehdichfür), Karlova Huť (Karlbachhütte), Nový Dvůr (Neuhof), Pleš (Plöß), Smolov (Schmolau), Újezd Svatého Kříže (Heiligenkreuz b. Weißensulz) und Železná (Eisendorf). Grundsiedlungseinheiten sind Bělá nad Radbuzou (Weißensulz), Bystřice (Wistersitz), Čečín (Zetschin), Černá Hora (Tschernahora), Doubravka (Dobraken), Karlova Huť (Karlbachhütte), Nový Dvůr (Neuhof), Pleš (Plöß), Smolov (Schmolau), Újezd Svatého Kříže (Heiligenkreuz b. Weißensulz). Das Stadtgebiet gliedert sich in die Katastralbezirke Bělá nad Radbuzou, Bystřice u Bělé nad Radbuzou, Čečín, Černá Hora u Bělé nad Radbuzou, Doubravka u Bělé nad Radbuzou, Pleš, Smolov, Újezd Svatého Kříže und Železná u Smolova. Auf den Fluren von Bělá nad Radbuzou (Weißensulz) befinden sich auch die nach 1945 untergegangenen Dörfer Lískovec (Haselberg) und Růžov (Rosendorf).
Die Steinbrücke über die Radbuza wurde von 1703 bis 1723 auf Anregung von Anna Marie Terezie Metternich, Besitzerin des Herrschaftsgutes Bela, gebaut. Sie ersetzte eine vorher vorhandene Holzbrücke. Die Brücke hat acht Bögen und sechs Pfeiler. Jeder Pfeiler ist mit einer Heiligenfigur geschmückt. Die Figuren auf der Westseite stellen von Norden nach Süden dar:
Sources: de.wikipedia.org
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.
Suppliers typically quote a percentage derived from reverse-phase HPLC peak area. That figure reflects the relative amount of the main peak and does not by itself confirm identity or exclude related impurities. Mass spectrometry is commonly paired with it for confirmation.
Peptides purified by reverse-phase chromatography often carry trifluoroacetate as a counter-ion, which adds mass and can affect solubility and apparent behavior in assays. Acetate and hydrochloride forms are also offered. Knowing which form is present matters when calculating how much peptide a given weight contains.
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.