TB-500
Also known as Thymosin beta-4 fragment, Tβ4 fragment, TB4
TB-500 is a synthetic peptide built around the actin-binding region of thymosin β4. A research-use profile: its Tβ4 lineage, the actin-sequestering biology it descends from, and how it's handled.
TB-500 is best understood not as a molecule that appeared on its own, but as a fragment with a parent. That parent is thymosin β4 — Tβ4 — a small, highly conserved protein found across many tissues whose defining job in cell biology is binding monomeric actin. Almost every accurate statement about TB-500 traces back to that lineage.
This page stays on the verifiable side of the record: where the sequence comes from, the actin biology that makes Tβ4 interesting to researchers, and how the peptide is handled in a lab. It does not make claims about outcomes, which are neither settled nor appropriate here.
TB-500 is the research-market name for a synthetic peptide based on thymosin β4 (Tβ4), a naturally occurring 43-residue actin-sequestering protein. The material distributed under this name centers on the actin-binding region of Tβ4 rather than the full-length protein.
The thymosin β4 lineage
Thymosin β4 is one of the most abundant members of the β-thymosin family, a group of small, unstructured proteins that regulate the pool of unpolymerized actin inside cells. Because Tβ4 is so widely distributed and so conserved between species, it has long been a subject of cell-motility and cytoskeleton research.
TB-500 is the name that circulates in the research-peptide market for a synthetic construct based on Tβ4's functional core rather than the entire 43-residue protein. When people describe TB-500 as 'a thymosin β4 fragment,' this is the relationship they mean — it is downstream of Tβ4, not a separate discovery with its own independent biology.
Actin sequestration — the biology it inherits
The single best-characterized activity of thymosin β4 is actin sequestration: it binds G-actin (the monomer form) and holds it in reserve, buffering how much is available to assemble into filaments. This puts Tβ4 at the center of research into cell migration and cytoskeletal remodeling, processes that matter anywhere tissue is being reorganized.
The short actin-binding motif conserved in the β-thymosins is the reason a fragment can retain interest at all — the interaction with actin is localized to a defined region of the sequence. This is why TB-500 is studied in the context of the same cell-movement and tissue-remodeling questions as its parent protein, and why it is so often mentioned alongside BPC-157 in soft-tissue recovery literature despite the two being structurally unrelated.
Reading a TB-500 certificate of analysis
Because 'TB-500' is a market name rather than a single rigid IUPAC entity, the certificate of analysis matters more here than usual. A trustworthy lot ties a stated purity to an actual method — mass spectrometry and HPLC — and to a batch identifier, so the mass and the dominant chromatographic peak can be checked against the intended peptide. Purity figures with no method and no batch number tell you very little. Every lot we list is tied to its own certificate; verify yours by its batch number.
These are research areas the compound is associated with in the literature — not medical claims or intended uses.
Handling & storage
Supplied lyophilized. Stored sealed and cold; in research settings it is reconstituted with bacteriostatic water only when a protocol calls for it, then kept refrigerated. Handle per accepted laboratory practice.
Verify a certificate by lot →Common questions
No. Thymosin β4 is a full-length, naturally occurring 43-residue protein. TB-500 is a synthetic peptide based on the actin-binding region of Tβ4, so it is derived from that protein rather than identical to it.
Its parent protein, thymosin β4, is a classic actin-sequestering peptide — it binds monomeric actin and buffers the pool available for filament assembly. That actin biology is the reason the fragment is studied at all.
The two come up together because they are studied in overlapping soft-tissue and recovery research contexts, not because they are related molecules — structurally they are entirely different.
This monograph is a research-use reference. It describes composition and the contexts in which the compound has been studied — it is not medical advice, a description of effects, or a recommendation for use. Sold strictly for laboratory and research use; not for human or animal consumption.