TB-500

Overview

Torsena supplies research-grade TB-500 to qualified laboratories across the European Union. Furthermore, we hold stock in Europe, so orders ship without intra-EU customs delay. Batch documentation is available on request.

Lot & Supply Format

• Purity. Typically ≥99%, and a batch-specific CoA is available on request.
• Formulation. Mannitol-free, so no bulking agents or buffer salts dilute the material.
• Presentation. Lyophilized peptide, sealed in glass research vials.
• Quantities. Single vials as standard, though we also quote bulk on request.
• Shipping. Dispatched from Europe, and always with temperature-appropriate packaging.

TB-500 and Thymosin Beta-4: What the Names Mean

Before anything else, a clarification the peptide market handles badly. TB-500 is not a defined chemical entity. No IUPAC or USP standard defines it, and the name originated as a vendor convention rather than a biochemical designation. Consequently two different molecules ship under it.

Thymosin beta-4 is the full-length endogenous protein: 43 amino acids, roughly 4,963 Da, encoded by the TMSB4X gene and present in virtually every nucleated human cell. It is the most abundant member of the beta-thymosin family.

The TB-500 fragment, formally named fequesetide, is a synthetic seven-residue peptide corresponding to positions 17 to 23 of that protein, sequence Ac-LKKTETQ, roughly 843 Da. That stretch is the actin-binding region.

Therefore the two share a mechanism but differ in mass by a factor of about six, and they produce entirely different mass spectrometry fingerprints. Because most published research used full-length thymosin beta-4 rather than the fragment, checking which form a study used is worthwhile before extrapolating from it.

This product is full-length thymosin beta-4, 43 amino acids. The molecular weight on your batch CoA confirms it.

Supplied exclusively for in-vitro and ex-vivo research by qualified laboratories. Not intended for human or animal administration.

Functional Domains

Full-length thymosin beta-4 carries several distinct active regions, and this is the practical reason the fragment is not equivalent to the whole protein.

Notably the fragment reproduces only the third of these. Consequently protocols examining anti-fibrotic or anti-apoptotic endpoints need the full protein, whereas actin and migration work can use either.

Mechanistic Overview

Actin sequestration. Thymosin beta-4 binds monomeric G-actin in a 1:1 complex, which holds it back from polymerising into F-actin filaments. It is the primary intracellular G-actin sequestering peptide, so it effectively maintains the monomer reservoir cells draw on. Therefore studies use it to manipulate cytoskeletal dynamics directly rather than through upstream signaling.

Cell migration. The LKKTETQ region at positions 17 to 23 carries this activity, and researchers have characterised it across multiple cell lineages in migration assays. Because actin turnover governs how cells move, sequestration and migration are two views of the same mechanism.

Vascular endpoints. Preclinical work has examined tube formation and endothelial migration, so the peptide appears regularly in angiogenesis pathway investigation.

Inflammatory signaling. Studies describe effects on cytokine cascades and inflammatory mediator expression. Note that the Ac-SDKP region at the N-terminus is associated with anti-fibrotic activity specifically, and that region exists only in the full-length protein.

Research Context

Full-length thymosin beta-4 has been through formal clinical development. RegeneRx Biopharmaceuticals ran Phase I and Phase II trials under the designations RGN-352 and RGN-259, targeting cardiac repair and ocular surface healing respectively. Phase I safety data covers 84 healthy volunteers.

By contrast, the seven-residue fragment has no published randomised controlled human trial data. Therefore most of what circulates as “TB-500 research” is in fact thymosin beta-4 research, and the extrapolation from one to the other is an assumption rather than a finding.

TB-500 vs BPC-157

Thymosin beta-4 specifications

Amino Acid Sequence

Ac-Ser-Asp-Lys-Pro-Asp-Met-Ala-Glu-Ile-Glu-Lys-Phe-Asp-Lys-Ser-Lys-Leu-Lys-Lys-Thr-Glu-Thr-Gln-Glu-Lys-Asn-Pro-Leu-Pro-Ser-Lys-Glu-Thr-Ile-Glu-Gln-Glu-Lys-Gln-Ala-Gly-Glu-Ser

One-letter code: Ac-SDKPDMAEIEKFDKSKLKKTETQEKNPLPSKETIEQEKQAGES
Peptide length: 43 amino acids
Type: Linear, N-terminal acetylation
Actin-binding motif: LKKTETQ, positions 17-23

Reconstitution & Storage

At 43 residues this is a substantially larger molecule than most peptides in our range, and that changes the handling.

• Solvent. Sterile water or a suitable aqueous buffer.
• Freeze-thaw. Minimise cycles, since larger peptides lose activity faster across them than short ones do.
• Aliquoting. Worth doing properly here, because it is the practical defence against repeated thawing.
• Short-term storage. 2-8°C for reconstituted aliquots.
• Long-term storage. Freeze at -20°C.

Keep lyophilized material at -20°C and protect it from light. Furthermore, let vials warm to room temperature before opening, because condensation otherwise pulls moisture into the powder. Note also that the sequence carries a methionine at position 6, so minimise air exposure, since methionine oxidises to methionine sulfoxide and shows up as a plus sixteen mass shift.

Analytical Documentation

We provide batch-specific Certificates of Analysis on request. Typically the documentation covers three areas.

• Purity. Determined by reverse-phase HPLC.
• Identity. Confirmed by mass spectrometry, which also establishes whether material is full-length or fragment.
• Physical checks. Namely appearance and solubility verification.

Why Choose Torsena for TB-500

• Documentation. We send batch CoAs on request, and they state the molecular weight so you can confirm which form you have.
• No fillers. Mannitol-free, so nothing dilutes the material you paid for.
• EU distribution. We ship from European stock, and therefore intra-EU orders clear no customs.
• Direct contact. You reach the team directly, rather than a ticket queue.

Frequently Asked Questions

Is TB-500 the same as thymosin beta-4?
Not necessarily, and this is the most common confusion around the compound. Thymosin beta-4 is the full 43-amino-acid protein at roughly 4,963 Da. The TB-500 fragment, formally fequesetide, is a seven-residue synthetic peptide covering positions 17 to 23, sequence Ac-LKKTETQ, at roughly 843 Da. Both ship under the TB-500 name because no standard defines it, so check the molecular weight on the CoA to know which you have.

How do you tell which form you have?
The molecular weight on the Certificate of Analysis settles it. Approximately 4,900 Da, or a CoA stating 43 amino acids, means full-length thymosin beta-4. Approximately 840 Da means the seven-residue fragment. The two produce completely different mass spectrometry fingerprints, so there is no ambiguity once you look.

Does the fragment do the same thing as the full protein?
Partially. The fragment reproduces the actin-binding and migration activity at residues 17 to 23, but the full protein carries additional domains the fragment lacks, notably Ac-SDKP at residues 1 to 4 associated with anti-fibrotic activity, and a broader N-terminal region associated with anti-apoptotic effects. Therefore protocols targeting those endpoints need the full-length protein.

What is the molecular weight of thymosin beta-4?
4963.44 g/mol, with the formula C212H350N56O78S. The single sulfur comes from the methionine at position 6, which is also why air exposure should be minimised during handling.

Which form did the published research use?
Mostly the full-length protein. RegeneRx Biopharmaceuticals ran Phase I and Phase II trials on thymosin beta-4 under RGN-352 and RGN-259, whereas the seven-residue fragment has no published randomised controlled human trial data. Consequently extrapolating fragment behaviour from full-protein studies is an assumption rather than an established equivalence.

Related Research Compounds

Researchers working on tissue repair and cytoskeletal dynamics usually look at these as well.

• GHK-Cu. A copper tripeptide, and therefore a complementary tool for extracellular matrix endpoints.
• Klow80. A four-component preparation containing TB-500, namely where a protocol examines several repair pathways together.

Otherwise, browse the full catalog at the Torsena shop.