The short version of actin binding fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-08-01. Anything still debated is marked as such rather than presented as settled.
Published work involving this sequence spans actin-binding assays, cell-migration studies, wound-healing models, and cardiovascular or musculoskeletal experiments. Much of the biological rationale derives from in vitro systems and animal models, and the number of controlled human studies is small. Reported outcomes vary across preparations, doses, and routes, which complicates comparison between studies. Reviews generally describe the evidence base as preliminary rather than settled. Mechanistic explanations are often proposed by analogy to the parent protein rather than demonstrated directly.
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.
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.
TB-500 is a synthetic peptide whose sequence corresponds to a short fragment near the N-terminus of thymosin beta-4, a small protein present in most mammalian cells. The fragment is commonly cited as containing the actin-binding region of the parent molecule, which is why it appears in laboratory work on cell migration and tissue repair. Suppliers distribute it as a lyophilised powder intended for research use. Its identity is defined by amino acid sequence and by the presence of an acetyl group on the N-terminal residue.
| 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 |
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.
Once dissolved, the peptide is far less stable than the dry powder. Aqueous solutions are subject to hydrolysis, oxidation at susceptible residues and gradual loss of material through adsorption onto glass and plastic surfaces. Terminal glutamine can cyclise under some conditions, producing a related species that complicates purity assessment. Dilute solutions tend to lose a larger fraction of material to surfaces than concentrated ones. Buffers, pH and ionic strength all influence the rate of change, so stability figures are only meaningful when those parameters are stated alongside the storage interval.
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.
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.
Research interest in thymosin beta-4 fragments centres on actin sequestration, cell migration and tissue repair models. Most published work uses cultured cells or animal wound and cardiac preparations, and findings are generally described as preliminary. No fragment of this protein has been approved as a therapeutic product by major regulators. Reviews of the field note inconsistent dosing, delivery routes and outcome measures across studies, which complicates direct comparison. The material is best understood as a laboratory reagent with an active but unresolved research literature.
TB-500 is a catalogue name applied to a synthetic peptide related to thymosin beta-4, an actin-binding protein found in most mammalian cells. Suppliers do not use the label consistently: some describe it as the full 43-residue protein, others as a short fragment from the actin-binding region, and others as a related tetrapeptide. Because the name is commercial rather than chemical, two products sold under it may not contain the same molecule. This naming ambiguity is the first point to check in any description of the material.
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.
== Leben == Herbert Albers, Sohn des Kaufmanns Johannes Albers und der Theda Albers, geborene von der Werp, studierte Medizin, zunächst in Marburg, später in Jena und Kiel. Albers war Mitglied der SA ab dem 9. Juni 1933, er beantragte am 15. Juni 1937 die Aufnahme in die NSDAP und wurde rückwirkend zum 1. Mai desselben Jahres aufgenommen (Mitgliedsnummer 4.302.534). Ende 1939 trat er schließlich der SS und der Marburger Turnerschaft Philippina bei. Nach Forschungen in der Anatomie sowie Weiterbildung in Innerer Medizin und Chirurgie wandte Albers sich der Frauenheilkunde zu. Bereits vor seinem medizinischen Staatsexamen veröffentlichte er eine Studie über die Hyperchlorämie bei Hyperemesis gravidarum. 1936 wurde er in Kiel zum Dr. med. promoviert. Sein Lehrer in Kiel, der Gynäkologe Robert Schröder, holte ihn an die Universität Leipzig, wo Albers sich 1940 habilitierte. 1944 bis 1945 war er außerplanmäßiger Professor für Gynäkologie und Geburtshilfe in Leipzig. Nach dem Zweiten Weltkrieg gründete er 1947 im friesischen Sanderbusch mit Genehmigung des Oldenburgischen Landesfürsorgeverbandes das Oldenburgische Landeskrankenhaus Sanderbusch. Nach einem Jahr an der Paracelsusklinik in Marl kam er 1958 als Chefarzt an die Frauenklinik der Städtischen Krankenanstalten in Wiesbaden. Unter anderem unterrichtete er dort im Auftrag der Universität Mainz in Geburtshilfe und Gynäkologie. Sie ernannte ihn 1969 zum außerplanmäßigen Professor. Albers ging 1974 in Pension. Herbert Albers ist Verfasser von über 148 Fachpublikationen sowie mehrerer Fach- und Sachbücher.
== Literatur == Gestorben. In: Deutsches Ärzteblatt. Band 98, 2001, S. 28–29. Albers, Herbert. In: Walter Habel (Hrsg.): Wer ist wer? Das deutsche Who’s Who. 24. Ausgabe. Schmidt-Römhild, Lübeck 1985, ISBN 3-7950-2005-0, S. 10.
== Weblinks == Literatur von und über Herbert Albers im Katalog der Deutschen Nationalbibliothek Herbert Albers im Professorenkatalog der Universität Leipzig Herbert Albers im Mainzer Professorenkatalog
Prymnesium parvum ist eine Art (Spezies) von einzelligen Mikroalgen (etwa 10 μm lang und 3 bis 4 μm breit) aus dem Taxon der Haptophyta, dessen Mitglieder meist in mariner und eher tropischer Umgebung leben. P. parvum ist biflagellat (doppelt begeißelt), was es der Alge ermöglicht, sich zu bewegen. Man findet sie daher auch in der Regel schwebend in der Wassersäule, am häufigsten in Ästuar- oder Meeresgewässern. Sie kann aber auch in Binnengewässern vorkommen, die einen relativ hohen Mineralgehalt aufweisen. Die Typlokalität ist ein Brackwasserteich auf der Isle of Wight, England. P. parvum kommt heute kosmopolitisch (weltweit) vor, unter anderem in der Ostsee, Europa, China, Australien, den USA und Marokko. P. parvum kann schädliche Algenblüten (englisch harmful blooms, HABs) in Binnen- und Küstengewässern hervorrufen, die zu verheerenden Fischsterben mit ökologischen sowie wirtschaftlichen Schäden führen. Wegen der Pigmente, die ihr einen goldgelben Schimmer verleihen, wird P. parvum manchmal „Goldalge“ (englisch golden algae, golden brown algae) genannt. Die Bezeichnung Goldalgen ist jedoch ein nicht-taxonomischer Begriff, unter dem verschiedene Gruppen der Stramenopilen aufgrund ihrer Farbe subsumiert werden, darunter die Goldbraunen Algen (Chrysophyceae), die Goldgrünen Algen (Bacillariophyta) oder die Kieselalgen (Bacillariophyta). Als Haptophyten besitzen die Mitglieder der Gattung Prymnesium neben den Geißeln ein weiteres Anhängsel (Haptonema), das bei diesen drei Goldalgen-Gruppen nicht vorkommt.
Sources: de.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.
It is a synthetic peptide based on a short sequence near the start of thymosin beta-4. It is supplied as a research chemical rather than as a licensed pharmaceutical product.