TB-500 (Thymosin Beta-4)

TB-500 is a research peptide closely associated with thymosin beta-4 (Tβ4), a naturally occurring 43-amino-acid protein found in nearly all mammalian cells. Thymosin beta-4 carries CAS number 77591-33-4 and the molecular formula C212H350N56O78S, with a molecular weight near 4963.4 g/mol. The label TB-500 comes from the research-chemical market, and in practice it refers either to synthetic thymosin beta-4 or to its active actin-binding region, the short sequence Ac-Leu-Lys-Lys-Thr-Glu-Thr-Gln.

The molecule’s defining property is that it binds G-actin and helps regulate actin polymerization, the process cells use to build and reorganize their internal scaffolding. That single biochemical role connects to the wide set of repair and cell-motility models in which it appears. It is supplied as a lyophilized powder for laboratory reconstitution.

Thymosin beta-4 was first isolated from thymus tissue and its sequence reported in 1981 by Low and Goldstein, who described it within the beta-thymosin family. A broad 2007 overview of beta-thymosins by Hannappel in the Annals of the New York Academy of Sciences laid out their biochemistry and distribution (PubMed 17468232).

A 2012 review by Goldstein and Hannappel in Expert Opinion on Biological Therapy summarized thymosin beta-4 as a multifunctional regenerative peptide and surveyed its preclinical and clinical research directions (PubMed 22074294). Work has extended into specific tissue systems, including ophthalmic models reviewed by Sosne in 2018 (PubMed 30063853) and cardiac injury models discussed by Bjorklund and colleagues in 2020 (PubMed 31333080).

As with many peptides in this category, the most developed evidence is preclinical. Human clinical data exists for some research directions but remains limited overall.

The central mechanism described in the literature is actin sequestration. Thymosin beta-4 is one of the main G-actin-binding molecules in cells, and by holding monomeric actin it influences how quickly cells can assemble the filaments needed for migration and structural change. Research connects this to cell migration, angiogenesis, and modulation of inflammatory signaling in injury models.

The marketed TB-500 fragment (Ac-LKKTETQ) is studied because it carries the actin-binding motif while being far smaller and easier to synthesize than the full protein. Researchers should note that the full Tβ4 protein and the short fragment are not identical and may behave differently in a given assay.

TB-500 is frequently studied next to BPC-157 in soft-tissue repair models, though the two are biochemically distinct. Most published TB-500 and Tβ4 findings come from animal and cell-based systems. Researchers should consult PubMed for current work.

Lyophilized TB-500 is stored at -20°C for long-term holding, shielded from light, and repeated freeze-thaw cycles are avoided. Stability for a given lot is documented on its Certificate of Analysis. Brief holding at 2°C to 8°C is workable for shorter windows while the vial is kept away from light and moisture.

Larger peptides and proteins can be sensitive to repeated freeze-thaw cycles, which are avoided. The lot-specific Certificate of Analysis is the authoritative source for a given batch.

Reconstitution means returning a lyophilized compound to solution. This page gives no preparation procedure: solvent, concentration and handling steps belong to the methodology of the study being reproduced, not to a compound reference. TB-500 is handled as aqueous-soluble material.

Lyophilized material is hygroscopic, so a sealed container is allowed to reach ambient temperature before it is opened. Solubility and water-content figures for a given lot appear on its Certificate of Analysis.

Identity and purity of research-grade TB-500 are established analytically, by HPLC with mass spectrometric confirmation of the expected mass. Verified purity is documented per lot on the Certificate of Analysis. Because TB-500 can refer to either the full Tβ4 protein or the short active fragment, the COA and product description should make clear which material is supplied.

On a Certificate of Analysis, check the HPLC purity, the mass-spec confirmation, and the stated peptide identity. peptides.com publishes lot-specific lab reports so buyers can confirm exactly what a given vial contains before purchase.

TB-500 is commonly cross-referenced with other repair-context research peptides:

• BPC-157.
  Studied in overlapping soft-tissue repair models and offered in combination formats. 
• GHK-Cu.
  A copper-binding peptide studied in matrix-remodeling and skin models. 
• Thymosin Alpha-1.
  Another thymus-derived peptide, studied in immune-context research (entry forthcoming).

Hannappel E (2007). beta-Thymosins. Annals of the New York Academy of Sciences.
PubMed 17468232

Goldstein AL, Hannappel E, et al. (2012). Thymosin beta-4: a multi-functional regenerative peptide. Basic properties and clinical applications. Expert Opinion on Biological Therapy.
PubMed 22074294

Sosne G (2018). Thymosin beta 4 and the eye: the journey from bench to bedside. Expert Opinion on Biological Therapy.
PubMed 30063853

Bjorklund G, Dadar M, et al. (2020). Thymosin beta-4: A Multi-Faceted Tissue Repair Stimulating Protein in Heart Injury. Current Medicinal Chemistry.
PubMed 31333080

peptides.com carries TB-500 in research-grade formats including lyophilized vials, capsules, and a liquid spray, plus combination formats with BPC-157. Each ships with a batch-specific Certificate of Analysis.

• Browse all TB-500 research products
• Real Peptides TB-500 (10mg vial)
• Catalyst Compounds TB-500 (10mg vial)
• Catalyst Compounds TB-500 Liquid Spray
• BPC-157 + TB-500 combination (Wolverine Blend)
• Collections: Research Vials, Liquid Sprays. Documentation: COA and Lab Testing.

These products are sold for Research Use Only and are not intended for human consumption.