What Is TB-500 (Thymosin Beta-4)? A Researcher’s Guide
TB-500 is the name commonly used in the research-chemical market for synthetic thymosin beta-4 (Tβ4), a naturally occurring 43-amino-acid peptide. This guide explains what thymosin beta-4 is, how it is characterized, why it is studied, and how laboratories handle it.
What is thymosin beta-4?
Thymosin beta-4 is a small, highly conserved peptide found in most mammalian cell types. It was first isolated in the early 1980s from a thymus extract known as “thymosin fraction 5,” which is how it got its name. Its best-characterized biochemical role is binding monomeric G-actin, which makes it one of the main actin-sequestering molecules inside cells.
TB-500 chemical profile
| Compound | Thymosin beta-4 (TB-500) |
|---|---|
| Length | 43 amino acids, N-terminally acetylated |
| CAS number | 77591-33-4 |
| Molecular formula | C212H350N56O78S |
| Molecular weight | ≈4963.4 g/mol |
| Typical research form | Lyophilized solid in a sealed vial |
TB-500 vs. thymosin beta-4: is there a difference?
In scientific literature the peptide is called thymosin beta-4. “TB-500” is a market name. Some suppliers use “TB-500” for the full 43-amino-acid sequence and others for a shorter fragment, so researchers should always confirm the exact sequence and molecular weight on the product specification before using a material.
Why researchers study thymosin beta-4
Because of its role in actin dynamics, thymosin beta-4 is studied in in-vitro and animal models of cell migration, cytoskeletal organization and tissue biology. It is often examined in the same study programs as BPC-157.
Regulatory status
Thymosin beta-4 is not an FDA-approved drug and is not a dietary supplement ingredient. It is sold in the United States only as a research material, without claims about effects in humans or animals. It also appears on sports anti-doping prohibited lists.
Storage and handling
- Store sealed lyophilized vials at −20 °C, dry and protected from light.
- Minimize freeze-thaw cycles and log lot numbers for traceability.
What to look for in a TB-500 supplier
- A stated sequence and molecular weight, so you know whether you are getting full-length Tβ4.
- Independent third-party testing of every lot (purity and identity).
- Sealed, lyophilized vials with lot numbers and expiration dates.
- Strict research-use-only labeling.
TB-500 at Attestryn
Attestryn offers TB-500 10 mg and a BPC-157 / TB-500 5/5 mg blend. Every lot is third-party tested before release and ships from within the United States.
TB-500 FAQ
What does TB-500 stand for?
TB-500 is a trade name for synthetic thymosin beta-4. It is not a formal scientific name.
How long is thymosin beta-4?
Full-length thymosin beta-4 is 43 amino acids long, with a molecular weight of about 4963 g/mol.
Is TB-500 approved for human use?
No. It is not FDA-approved and is sold only for laboratory research use.
This article is for educational and informational purposes about laboratory research materials. Attestryn products are sold for laboratory research use only. They are not drugs, foods, cosmetics or dietary supplements, are not for human or veterinary use, and have not been evaluated by the FDA. Attestryn does not provide dosing, reconstitution or administration information.