What is TB-500? Actin-fragment research

Research-use notice: This article is laboratory and educational information only. It is not medical or legal advice, and it does not include how-to-use instructions. BlueNex Labs materials are research use only and are not intended for human or veterinary use. Research-use-only labelling is not a Health Canada authorization.

Publication status: Prepared for the BlueNex Labs Research Knowledge Centre. Literature and library notes checked September 24, 2026. Primary papers and the public COA library can change; verify the lot report in hand before an assay.

TB-500, on this catalogue, is a synthetic fragment modelled on an actin-binding region of thymosin beta-4. It is not thymosin alpha-1, and it is not the gastric pentadecapeptide BPC-157. This page stays with the fragment. For the single-peptide shop URL, see TB-500 10 mg. For the page that discusses the two sequences together, see BPC-157 and TB-500 as paired laboratory topics, and that page is still not a protocol.

Full-length thymosin beta-4 versus a short fragment

Thymosin beta-4 is a 43-residue actin-monomer sequestering peptide. Vancompernolle, Goethals, Huet, Louvard, and Vandekerckhove mapped the contact with actin in The EMBO Journal in 1992 (PMID 1464307, PMC556949). They localized a conserved hexapeptide, LKKTET, corresponding to residues 17–22, as a major electrostatic contact, and they showed that short synthetic pieces of the N-terminal region could still affect actin polymerization in the test tube, though less tightly than the intact peptide. The N-terminal acetylated tetrapeptide of the full-length protein is a different fragment discussed in other papers. It is not what this catalogue means by TB-500.

The catalogue nickname is not itself a sequence. Vendors have used "TB-500" both for short actin-site peptides and, in some analytical reports outside this shop, for material whose mass matched the 43-residue protein. BlueNex Labs does not ask you to guess. The controlling document is the observed mass on the lot report, compared with the sequence your method requires. A neighbouring product's PDF does not stand in for that report.

What the actin papers actually measure

The EMBO experiments measure inhibition or stimulation of salt-induced actin polymerization, using defined peptide concentrations in a biochemical assay. Later cell papers ask whether thymosin beta-4 changes actin organization inside a given cell type. Those readouts are cytoskeletal. They are not a mobility program and they are not evidence about a person. When you cite them, cite the system: G-actin sequestration, polymerization in vitro, or a named cell-migration assay.

Angiogenesis-marker and motility models appear in the broader thymosin beta-4 literature. Keep the fragment and the full-length protein distinct when you write methods. A motif that is necessary for actin binding in a truncation study is not proof that every commercial fragment has been run through the same assay.

Not thymosin alpha-1

Thymosin alpha-1 is a 28-residue peptide from a different thymic precursor. It is discussed in T-cell and innate-immune signalling models, not as an actin-sequestering fragment. For the separate note, see What is Thymosin Alpha-1?, and the separate vial is Thymosin Alpha-1 10 mg. A search page that blends the words "thymosin" is how lots get mis-filed. Sequence length alone separates them: 28 residues versus a beta-4 fragment versus the 43-residue beta-4 protein.

Separate SKUs, separate analytical data

The TB-500-only listing is one product. Dual fills are others: BPC-157 / TB-500 5 mg/5mg and 10 mg/10mg. Each has its own Janoshik report: the 5 mg/5 mg blend, the 10 mg/10 mg blend, and the TB-500-only vial, whose report is the TB-500 10 mg certificate. A blend chromatogram does not identify the single-peptide cake. Read how to read a peptide COA before you accept a screenshot in place of the report.

The gastric pentadecapeptide has its own structure note (What is BPC-157? Structure & research), its own vial (BPC-157 10 mg), and its own certificate, which is not interchangeable with this one. Cellular SKUs as a group are listed under Cellular & Biological Peptides.

Regulatory frame, briefly

When these names are advertised for human administration they are treated as drugs. Health Canada's enforcement notes are summarized in Are research peptides legal in Canada?. Research-use-only labelling on a laboratory vial does not convert the vial into a DIN product. The U.S. advisory discussion of bulk substances is a different jurisdiction; see the 2026 FDA peptide review note if you need that timeline. It does not authorize Canadian supply.

Handling the dry solid

Shipments are lyophilized cakes unless a listing says otherwise. Moisture, light, and temperature cycling are the stability risks. Receiving steps live in peptide storage for Canadian laboratories. Canada fulfilment is Interac e-Transfer, Canada Post Xpresspost, Burnaby desk, Port Moody PO Box on the label, inside Canada only. This page does not describe wetting technique or solution concentration. Those belong in your SOP.

Writing the fragment into a method file

A method file that says only "TB-500" will not survive an audit. Record the sequence you intended, including any N-terminal acetyl group, the expected monoisotopic or average mass, the observed mass on the report, the purity method, and the lot. If the report is not published, record that absence instead of filling the cell with a literature mass from the 43-residue protein. The EMBO truncation work showed that pieces of the N-terminal region can still interact with actin, and that they do so at higher molar excess than the intact peptide. That comparison is a reason to specify which chain you have, not a reason to file every short peptide as interchangeable with thymosin beta-4.

When the experiment is a polymerization assay, write the peptide-to-actin ratio and the salt conditions, because those are what the 1992 paper actually varied. When the experiment is a cell-migration assay, name the cell type and the matrix coat. Angiogenesis-marker panels are yet another readout. Lumping them under one nickname hides which paper you are replicating.

Neighbour SKUs that are easy to confuse at the bench are the two BPC-157 blends and thymosin alpha-1. Label the secondary container with the shop slug, not with "thymosin" alone. Then point the study file at the COA reading guide so the next person can see why a blend chromatogram was rejected for this vial.

Three chains that share a thymosin beta-4 conversation

Is the catalogue name TB-500 the same chain as full-length thymosin beta-4? No. The intact protein is 43 residues, acetylated at the N terminus in the sequence work that defined it. The actin-contact hexapeptide LKKTET sits at residues 17–22 of that chain, which is the mapping in the 1992 EMBO paper already cited above. A third, shorter piece is the N-terminal tetrapeptide of the intact protein. Papers discuss that tetrapeptide as its own fragment. It is not the actin-site hexapeptide, and it is not what this catalogue means by TB-500. Three conversations, three lengths. A nickname does not choose among them.

Reference tables place the 43-residue protein near 5 kilodaltons. A fragment built on the LKKTET motif is far below that mass. The gap is the practical identity test. A mass that fits a short actin-site peptide cannot be filed as the intact protein, and a mass that fits the 43-residue protein cannot be filed as the hexapeptide. Vendors outside this shop have used "TB-500" for both kinds of material. BlueNex Labs does not resolve that ambiguity with the product name. The controlling record is the observed mass on a lot report for the vial in hand, compared with the sequence the method actually requires, including any N-terminal acetyl group the method expects.

The single-peptide report is in the public library at the TB-500 10 mg certificate row. The 5 mg/5mg blend and the 10 mg/10mg blend are different files. A blend chromatogram contains a second sequence. It cannot tell you whether the TB-500 portion was the short fragment or the 43-residue protein, and it cannot be pasted onto the single-peptide vial. For the primer that explains the document, see What is a peptide COA in Canada?. For the method note, see how to read a peptide COA. Use the TB-500 row for the observed mass rather than filling the mass cell from a textbook figure for the intact protein.

Sequence length also separates this fragment from thymosin alpha-1, which is 28 residues and has its own 10 mg vial. BPC-157 is a gastric pentadecapeptide with its own 10 mg vial and its own certificate anchor. None of those masses belong in the TB-500 cell. Write the chain you intended, the expected mass class (short fragment or 43-residue protein), and the observed mass if a report exists. If you only write the nickname, the file cannot be audited.

Frequently asked questions

Is TB-500 the same sequence as thymosin alpha-1?

No. Thymosin alpha-1 is a 28-residue thymic peptide with its own research note and its own 10 mg catalogue vial. TB-500 on this site is named as a thymosin beta-4 fragment. Confirm the mass on the lot report rather than equating the two names.

Does a blend Certificate of Analysis document the TB-500-only vial?

No. The public library lists a Janoshik report for the BPC-157 and TB-500 5 mg/5mg blend. That report does not document the TB-500-only vial or the 10 mg/10mg blend. The TB-500-only vial has its own report: the TB-500 10 mg certificate.

What does research use only mean for TB-500?

The solid is for laboratory and in-vitro work. The label is not a Health Canada authorization, and this note is not a protocol for people or animals.

How does Canada fulfilment work for this SKU?

Orders ship inside Canada after Interac e-Transfer checkout, on Canada Post Xpresspost, from the Burnaby desk with a Port Moody PO Box on the label. Transit time is not guaranteed.

Is the catalogue name TB-500 the same chain as full-length thymosin beta-4?

No. Full-length thymosin beta-4 is a 43-residue protein. TB-500 on this catalogue is named as a fragment modelled on the actin-binding region. The lot mass on the TB-500 10 mg certificate row is what separates those chains. A blend report is not that file.

Catalogue cross-reference

For the single-peptide listing, see TB-500 10 mg. The 5 mg/5 mg blend has its own report, the BPC-157 + TB-500 5 mg/5 mg certificate, which does not cover the TB-500-only vial. For the published purity report for this listing, see the TB-500 10 mg certificate row.

Orders ship inside Canada only after Interac e-Transfer checkout. Sold-out SKUs remain listed and cannot be added to the cart. Match each vial to its own Certificate of Analysis when a lot is published. Research use only. Not for human or veterinary use.