TB-500 Peptide
Seven residues clipped out of a 43-residue protein, and they happen to be the exact seven that grip actin. The rest of the protein turned out to be commentary.
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For research use only. Not for human or veterinary use.
What TB-500 Peptide is
The plain-language version, first.
It is studied for its role in regulating actin, a protein involved in cell migration and tissue repair, primarily in animal and cell models.
Thymosin beta-4 is a 43-residue protein your cells make in quantity. Somewhere in the middle of it sit seven residues doing the famous part of the job. > TB-500 is those seven, clipped out, capped with an acetyl group, and shipped. The seven-residue stretch is the actin-binding domain, and actin is arguably the most important protein you have never thought about. More on that below. One piece of housekeeping most sellers skip: TB-500 and full-length thymosin beta-4 are different products. We sell both, separately, because they are not the same molecule. It even has its own FDA registry entry, UNII QHK6Z47GTG, which is an identity document rather than an endorsement. _Seven amino acids with paperwork. The interesting question is what the other thirty-six were for._
What TB-500 peptide actually does
Mechanism studied, not outcome promised.
Sequestering actin monomers sounds like blocking polymerisation. In practice it maintains a large ready pool the cell can deploy on demand, locally and fast.
TB-500 reproduces the actin-binding motif alone. Whether the fragment behaves like the intact protein in vivo has not been established in the literature.
Enzymes clip Ac-SDKP, an antifibrotic tetrapeptide with its own name, goralatide, off the opposite end of thymosin beta-4. The parent yields two separately named fragments.
Actin is what your cells are made of, in the structural sense. The internal skeleton, the thing that lets a cell hold shape, divide, and above all move. A cell crawling toward a wound is running on actin assembly the whole way. > Thymosin beta-4's job is actin logistics: it holds single actin units in reserve, like a hod carrier keeping bricks by the wall. The seven-residue fragment keeps that binding activity. The research question is whether managing the brick supply changes how fast the wall goes up, in the specific context of cells migrating where they are needed. Migration, note. Not supply. Its shelf-mate BPC-157 gets studied for the supply side, which is why the comparison between them is genuinely useful rather than forum noise. Here's the honest part. Actin biology is rock solid. The fragment's binding is real. _What that adds up to in a whole animal, let alone a person, is the part still living in rodent papers._
The research so far for TB-500 Peptide
Where the evidence is thin, we say so.
Eighteen registered clinical trials of full-length thymosin beta-4, including two completed phase 3 studies in dry eye disease and an ongoing Chinese programme in acute myocardial infarction. A well-characterised actin-sequestering mechanism dating to 1991. A 2012 analytical paper establishing what commercial TB-500 contains.
Any human interventional study of TB-500 itself. The June 2026 Applied Sciences review searched specifically for this across tendon, ligament, muscle, bone, cartilage, fat graft and spine, and found none. Direct TB-500 evidence is one rat and in vitro paper.
The file here is wide, animal, and complicated by an identity problem. A lot of published work concerns full-length thymosin beta-4, not the fragment, and results migrate from one to the other in casual writing constantly. > Same rule as everywhere else on this shelf: check the methods section for which molecule was actually used. The fragment itself has real in-vitro actin-binding data and animal injury-model work. Human trials of the fragment as sold: none. Prohibited in sport, explicitly named in anti-doping documentation. _A fragment with genuine biochemistry, a borrowed reputation from its parent, and the standard empty human column. Read carefully and it is an interesting molecule. Read carelessly and it is somebody else's data._
TB-500 10mg lyophilised. Ships same day out of BC.
TB-500 Peptide specs
The chemistry, exactly as released.
Who studies TB-500 Peptide
Who tends to order this one, and why.
A research compound does not have one audience. It has a handful of rooms where the same question keeps coming up, and the question is a different question in each of them.
Cytoskeletal biology
Thymosin beta-4 is the textbook example of monomer sequestration and one of the most abundant intracellular proteins in mammals. The fragment is a way to interrogate the binding motif in isolation.
Fragment pharmacology
A clean test case for a general question: how much of a protein function survives when you keep only the binding motif. Here the structural rationale is strong and the in vivo evidence is thin.
Analytical and anti-doping chemistry
Most of the rigorous published work on TB-500 as a product comes from anti-doping laboratories characterising what is actually in the vials, using Orbitrap and UHPLC-MS methods.
Comparative fragment studies
Thymosin beta-4 yields bioactive fragments from both ends, Ac-SDKP at residues 1 to 4 and the TB-500 motif at 17 to 23, which makes it useful for side-by-side fragment work.
Sold for laboratory research only. This is not guidance for personal use, and nothing here is a recommendation.
TB-500 Peptide backstory
How it got here.
In 1981 a group led by Allan Goldstein sequenced a 43-residue peptide out of calf thymus and published it in PNAS. The title called it a thymic hormone, and for a decade that is what the field believed it was, one of a family of thymus-derived signalling peptides isolated from a preparation called thymosin fraction 5.
Then in 1991 Safer, Elzinga and Nachmias published a paper in the Journal of Biological Chemistry with a title that quietly ended the idea: thymosin beta 4 and Fx, an actin-sequestering peptide, are indistinguishable. Fx had been isolated from human platelets.
The molecule was not a thymic hormone, was not particularly about the thymus, and was present at high concentration in cell after cell throughout the body. Its job was cytoskeletal housekeeping.
The name never changed. Every vial of TB-500 sold today carries a reference to a gland that had nothing to do with what the molecule turned out to be.
- 1
Named for the wrong organ
Sequenced from calf thymus in 1981 and published as a thymic hormone, then shown in 1991 to be identical to a peptide from platelets. The name stuck anyway.
- 2
The motif became the product
Residues 17 to 23, LKKTETQ, do the actin binding. Somebody cut them out, acetylated the front, and a market category was born.
- 3
A Y-chromosome twin
Humans carry a Y-linked paralog, TMSB4Y, differing at three residues. The LKKTETQ motif is identical in both, so males express a variant females do not.
Buying TB-500 Peptide in Canada
What ships, how fast, and the paperwork.
The hard part of buying research material is almost never the compound. It is the logistics. What leaves the building, how fast it moves, and what is in the box beside the vial. Here is ours, plainly.
Identity is the thing to check
TB-500 is a market name, not a standardised chemical identity. The reference definition is the acetylated heptapeptide Ac-LKKTETQ, FDA UNII QHK6Z47GTG. Published analytical surveys of the category have found product content inconsistent, so the sequence on the label matters more here than for most compounds.
Not the same as thymosin beta-4
Almost all published clinical work uses the full 43-residue protein, not the fragment. Anyone reading Tb4 trial results as TB-500 evidence is reading across a gap the literature does not bridge.
Keep it cold and dark
Short lyophilised peptides are best stored refrigerated and away from light. Handle as a laboratory reagent.
Stuff people ask about TB-500 Peptide
If your question is not here, email us. Real human answers.
No. Thymosin beta-4 is a 43-residue protein of roughly 4,963 daltons. TB-500 is a seven-residue acetylated fragment of it, Ac-LKKTETQ, at 889 daltons, corresponding to residues 17 to 23. Nearly all published clinical research uses the full protein. The two are routinely conflated in marketing, but they are different molecules and the evidence for one does not transfer automatically to the other.
No registered human interventional trial of TB-500 exists. A scoping review published in Applied Sciences in June 2026 screened 1,772 records, included 80 studies, and reported that no human interventional studies of thymosin beta-4 or TB-500 were identified in tendon, ligament, muscle, bone, cartilage, fat graft or spine categories. Direct TB-500 evidence in that review came down to a single rat and in vitro study. Full-length thymosin beta-4 does have registered trials, including completed phase 3 studies in dry eye disease.
Prohibited at all times, and named explicitly. The 2026 WADA Prohibited List includes Thymosin-beta-4 and its derivatives, giving TB-500 as the example, under S2.3, Growth Factors and Growth Factor Modulators. It applies both in and out of competition. The Canadian Centre for Ethics in Sport issued a four-year sanction to a U SPORTS athlete in April 2025 involving TB-500 and BPC-157.
Nobody has documented it. TB plausibly stands for thymosin beta, and 500 appears to be a product suffix, but we could not trace the name to any patent, trademark, company code or primary record, so we are not going to assert an origin story we cannot support.
Actin exists as free monomers and as assembled filaments, and cells shift between the two constantly. Thymosin beta-4 binds free monomers one-to-one and holds them out of the filament pool, functioning as a reservoir the cell can draw on quickly. The LKKTETQ stretch at residues 17 to 23 is the part that does the binding, which is why it became the basis for a fragment.
Yes, and it is barely used. The unacetylated heptapeptide LKKTETQ carries the WHO international nonproprietary name fequesetide. FDA registers the acetylated form as UNII QHK6Z47GTG with CAS 885340-08-9 and formula C38H68N10O14.
Good pairing options with TB-500 Peptide
What researchers stack alongside it.
Pairing is where research gets ahead of itself. These are the compounds researchers put in the same order as TB-500 Peptide, which is a statement about ordering habits, not about evidence. Two things in one cart have not been studied together unless somebody studied them together.
Everything alive builds its peptides from left-handed amino acids. In 1981 a South American tree frog turned up carrying one with a right-handed piece bolted into position two. The whole human record is a single 150-patient trial from 1985.
Cholera taught researchers how the gut's tight junctions swing open. Larazotide is the counter-move, and its phase 3 stopped for futility in 2022. The whole arc is on this page.
Order TB-500 Peptide right now
One last look before you decide.
Freeze-dried, COA on the page, ships cold
If you are researching TB-500 Peptide and you want a source you do not have to second-guess, start with the paperwork on this page. For research use only.
Not for human consumption. Not approved by Health Canada or any other regulatory body.
Page last updated August 20, 2026
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