What is TB-500?
In research-chemical catalogues, TB-500 most often labels a synthetic 43-amino-acid analogue of thymosin β-4 (Tβ4), a naturally occurring actin-binding peptide. That is the compound discussed on this page when we refer to a full-length analogue.
The name is not a chemical identifier. Some products sold as TB-500 have been characterized as a seven-residue fragment of Tβ4 (residues 17–23), not the 43-residue parent peptide. Those are different molecules. Online summaries that treat every “TB-500” listing as interchangeable with native thymosin β-4 are compressing that distinction away.
TB-500 is frequently mentioned alongside BPC-157. They are different peptides with different literatures. A combined product listing does not merge the evidence bases.
Naming and identity: analogue vs fragment
This is the main literacy problem in TB-500 coverage. Confirm identity from sequence, mass, and CAS — then read claims against that identity.
Two things sold under overlapping TB-500 labels
Typical identity
- Full-length analogue
- 43-amino-acid thymosin β-4 analogue
- Fragment (17–23)
- Acetylated 17–23 heptapeptide (Ac-LKKTETQ)
Approximate mass
- Full-length analogue
- ~4,963 Da
- Fragment (17–23)
- ~889 Da
What the name “TB-500” may mean
- Full-length analogue
- Vendor catalogues often use TB-500 for this analogue
- Fragment (17–23)
- Anti-doping / analytical papers have identified some TB-500 products as this fragment
Research implication
- Full-length analogue
- Closer in size to the parent peptide discussed in much of the Tβ4 literature
- Fragment (17–23)
- Isolated actin-binding motif; not the full peptide
Two things sold under overlapping TB-500 labels
| Check | Full-length analogue | Fragment (17–23) |
|---|---|---|
| Typical identity | 43-amino-acid thymosin β-4 analogue | Acetylated 17–23 heptapeptide (Ac-LKKTETQ) |
| Approximate mass | ~4,963 Da | ~889 Da |
| What the name “TB-500” may mean | Vendor catalogues often use TB-500 for this analogue | Anti-doping / analytical papers have identified some TB-500 products as this fragment |
| Research implication | Closer in size to the parent peptide discussed in much of the Tβ4 literature | Isolated actin-binding motif; not the full peptide |
Analytical work on a commercial TB-500 product (Esposito et al., Drug Testing and Analysis, 2012) identified N-acetylated Tβ4(17–23), not the full 43-residue peptide. That paper is about product identity in the marketplace — not a reason to assume every current listing is the fragment, and not a reason to assume every listing is the analogue.
Research overview
Thymosin β-4 has a substantial preclinical literature around actin sequestration and cell-migration models. Human and translational work, where it exists, generally involves the parent peptide or closely specified analogues — not commercial products identified only by the TB-500 trade name.
- Research themes often involve G-actin binding, cytoskeletal organization, and related signaling in experimental systems.
- Popular outcome and performance narratives usually outrun what commercial research-chemical listings can honestly support.
- Study quality, endpoints, and whether the test article matches a given vendor product all vary widely.
A responsible reading posture: map claims to a defined molecule, then ask whether the cited studies used that molecule.
Mechanism
Tβ4’s best-characterized biochemical role is binding monomeric G-actin via a conserved motif (LKKTET, residues 17–23), which influences actin polymerization dynamics. That motif is why the short fragment exists as a research tool: to test whether a given effect needs the whole peptide or can be reproduced by the isolated binding region.
Mechanism language is orientation, not proof of outcome. When a source jumps from “actin-binding motif” to guaranteed tissue or performance results, treat that as a credibility warning — especially on commercial pages.
Current evidence
Grade evidence by design quality, the identity of the test article, endpoints, and reproducibility — not by how often TB-500 appears next to BPC-157 in forums.
- Preclinical Tβ4 work with varying rigor and translational relevance
- Limited, uneven human certainty — and it is easy to mis-cite Tβ4 papers against a fragment listing
- Marketplace identity papers showing that the label “TB-500” has not always matched the 43-residue peptide
Two starting points in the published record, not a complete bibliography:
- Safer D, Elzinga M, Nachmias VT. Thymosin β4 and Fx, an actin-sequestering peptide, are indistinguishable. Journal of Biological Chemistry. 1991;266(7):4029-4032. PubMed 1999398. Foundational biochemistry of native Tβ4 — not a commercial TB-500 listing.
- Esposito S, Deventer K, Goeman J, Van der Eycken J, Van Eenoo P. Synthesis and characterization of the N-terminal acetylated 17–23 fragment of thymosin beta 4 identified in TB-500. Drug Testing and Analysis. 2012;4(9):733-738. PubMed 22962027. Marketplace identity: one analyzed TB-500 product was the short fragment, not the 43-residue peptide.
Citing papers is not an efficacy claim. Tβ4 biochemistry and a given vendor’s TB-500 SKU are easy to conflate; match the test article before importing results.
Frequently asked questions
Is TB-500 the same as thymosin β-4?
Not reliably. Thymosin β-4 is a 43-amino-acid peptide. Some research-chemical listings use “TB-500” for a synthetic 43-amino-acid analogue of that peptide. Analytical literature has also identified commercial material sold as TB-500 as a much shorter acetylated 17–23 fragment. Always check sequence, molecular weight, and CAS — not the marketing name.
Is TB-500 the same as BPC-157?
No. They are different peptides with different sequences and literatures. They are often discussed together, and some merchants sell blends, but a combined listing does not combine the evidence. See the BPC-157 guide for that compound.
Is TB-500 approved for human use?
Regulatory status varies by jurisdiction and changes over time. GRW Research does not present TB-500 or thymosin β-4 analogues as approved therapies. Treat this page as educational research context only.
Can this guide tell me how to dose TB-500?
No. We do not provide dosing, administration, stacking, or treatment protocols. Educational content here is intended to improve research literacy — not to guide personal use.
Why is the 17–23 fragment cheaper?
It is a different, much smaller molecule (seven amino acids versus 43). Price is not a discount on “the same TB-500.” A cheaper fragment listing is not interchangeable with a full-length analogue listing.
Why include affiliate links?
Some researchers evaluate commercial documentation after reading the science. When we include a merchant link, it is disclosed as affiliate-supported and positioned after educational context — never as medical endorsement.
How should researchers think about purity and testing?
Start with identity: analogue versus fragment, then molecular weight and CAS. After that, look for batch-level third-party testing, research-use labeling, and handling information. Always verify documents directly with the merchant.
Safety considerations
Safety discussions online are frequently incomplete and often assume a molecule the bottle may not contain. From an educational standpoint, separate:
- What has been reported for specified Tβ4 preparations
- What remains unknown for a given commercial analogue or fragment listing
- Legal, institutional, and sport-anti-doping constraints that may apply to research-use materials
This page does not provide safety clearance for personal use. Institutional review, applicable regulations, and primary literature remain essential.
Quality considerations
For TB-500, identity is the first quality check. Marketing names collide; certificates should not.
- Sequence / identity: 43-residue analogue versus 7-residue 17–23 fragment
- Molecular weight and CAS consistent with that identity (not copied from a different listing)
- Third-party testing documentation for the batch you are evaluating
- Clear research-use labeling and product identification
- Shipping, storage, and handling information clarity
TB-500 vs BPC-157
Educational comparison only — not a ranking, stack, or protocol. See the BPC-157 guide for the companion peptide.
TB-500 vs BPC-157 (educational framing)
Identity
- TB-500
- 43-amino-acid thymosin β-4 analogue; the TB-500 name is also used for a 7-residue fragment
- BPC-157
- 15-amino-acid synthetic peptide (pentadecapeptide)
Typical research themes
- TB-500
- Actin dynamics, cell migration, cytoskeletal organization
- BPC-157
- Tissue signaling in preclinical models
Evidence maturity
- TB-500
- Mostly preclinical; human Tβ4 work does not automatically apply to every TB-500 listing
- BPC-157
- Mostly preclinical; human certainty remains limited
First quality check
- TB-500
- Analogue vs fragment, mass/CAS, then testing documents
- BPC-157
- Sequence, testing documents, research-use labeling
TB-500 vs BPC-157 (educational framing)
| Criterion | TB-500 | BPC-157 |
|---|---|---|
| Identity | 43-amino-acid thymosin β-4 analogue; the TB-500 name is also used for a 7-residue fragment | 15-amino-acid synthetic peptide (pentadecapeptide) |
| Typical research themes | Actin dynamics, cell migration, cytoskeletal organization | Tissue signaling in preclinical models |
| Evidence maturity | Mostly preclinical; human Tβ4 work does not automatically apply to every TB-500 listing | Mostly preclinical; human certainty remains limited |
| First quality check | Analogue vs fragment, mass/CAS, then testing documents | Sequence, testing documents, research-use labeling |
Evaluating merchant listings
After the identity checks above, some readers evaluate merchant documentation for research-use materials. GRW Research may earn a commission through disclosed affiliate relationships when you use certain links.
The listing we point to is Swiss Chems’ TB-500 0.5 mg capsule, 60-count thymosin β-4 analogue listing. Review testing materials, confirm research-use terms, and treat any purchase decision as independent of this educational content.
Disclaimer
This page is for educational and informational purposes only. It is not medical advice, a diagnosis, a treatment plan, or an encouragement to use any compound in humans. Research chemicals may be restricted. Always verify laws, institutional requirements, and primary sources.
See also our medical disclaimer, editorial policy, and affiliate disclosure.
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