TB-500 is the name under which a synthetic peptide related to thymosin β4 (Tβ4) circulates on the research market. Tβ4 is a natural 43-amino-acid peptide whose main function is to sequester monomeric G-actin. That role in cytoskeletal dynamics is why the molecule is studied in models of wound healing, angiogenesis and cell migration [2].
Molecular identity
Tβ4 belongs to the β-thymosin family. Its key actin-binding motif sits in the central part of the sequence (LKKTETQ), and that motif governs how tightly the peptide holds G-actin. Work with N-terminally truncated and modified forms showed that both the N-terminus and this motif shape actin affinity [7]. Across suppliers, "TB-500" can denote full-length Tβ4 or a fragment, so the exact composition should always be checked against the batch COA (certificate of analysis).
Actin and the cytoskeleton
The core biochemical effect of Tβ4 is binding free G-actin at roughly 1:1, which holds a reserve of unpolymerized actin. This shifts the rate of filament assembly and disassembly, and with it cell motility and shape [2]. That mechanism underlies the hypotheses about the peptide's role in regeneration.
Wound healing and regeneration
In preclinical models, topical or systemic Tβ4 sped wound closure and raised the density of new vessels versus controls [1]. Reviews summarize these data as a consistent action profile in tissue-injury models, though the effects depend on model, dose and route [4].
Heart and other tissues
In cardiac models, Tβ4 activated integrin-linked kinase (ILK) and promoted migration and survival of heart cells after ischemic injury [3]. Corneal healing was studied separately: in vivo the peptide accelerated epithelialization and lowered inflammatory markers [5].
Angiogenesis
Another line of work is stimulation of vessel growth and hair-follicle development in experimental systems, linked to effects on endothelial cell migration [6]. These findings come mostly from animal and cell models.
Status and caveats
There is no approved human protocol for Tβ4/TB-500. The data above are preclinical. TB-500 at Longeva is a research-use-only (RUO) material, not a medicine. Batches ship with a COA from an independent third-party lab; the reports are available in the open COA archive.
Related pages
Buy the reagent: TB-500. Reconstitution figures from general sources: TB-500 reconstitution reference. Also available as the BPC-157 + TB-500 combination and standalone BPC-157.