Thymosin β4 (Tβ4)
Also known as: Timbetasin, Full-length thymosin beta-4, Thymosin Alpha-4
Thymosin β4 (Tβ4), also called Timbetasin or Full-length thymosin beta-4, is an actin-sequestering peptide in the Wound Healing / Cytoprotective class. Thymosin beta-4 is a 43-amino-acid peptide and the principal G-actin sequestering protein in most mammalian cells, binding monomeric actin through its LKKTETQ motif and maintaining the unpolymerised pool that cells draw on to remodel their cytoskeleton.
For research use only.
Key Facts
- CAS
- 77591-33-4
- Molecular Weight (MW)
- ≈4963 g/mol
- Half-life
- Not well established in humans
- FDA status
- Not Approved
- Administration Route
- —
- Frequency
- —
- Last updated
- Aug 30, 2026
- Reviewed
- Aug 30, 2026
- Targets
- G-actin
Vendor price snapshot
Each vendor counts once, at the median price per mg of its own listings; the typical range is the middle half of vendors. From public vendor listings collected in Dec 2025, so confirm the live price on the vendor site. Peptide Library does not sell peptides.
- Vendors listing this peptide
- 6
- Listed offers
- 10
- Median price per mg
- $9.00/mg
- Typical $8.00–$10.00/mg
Research summary
43-aa G-actin-sequestering peptide studied for wound healing and cardiac repair (timbetasin programs). Not FDA-approved. Distinct from the shorter TB-500 fragment.
Peptide Library's Thymosin β4 (Tβ4) profile summarises 5 cited studies listed in the Science section, the compound's regulatory status, and research-protocol parameters reported for it. It is a research reference, not medical advice.
Protocol
- Dosage Range
- Not established for humans
- Frequency
- —
- Cycle
- —
- Administration Route
- —
- Reconstitution Guide
- —
- Timing Notes
- Regulatory agencies note TB-500 is not approved for human therapy.
Not yet checked against primary sources
These figures are compiled from earlier reference material. They have not been verified against FDA labelling, registered trials or published literature, no citation is attached to them, and none of them is a recommended dose. Thymosin β4 (Tβ4) is queued for dosage evidence review.
Compare reported doses across the whole librarySequence & molecular data
| Molecular formula | C212H350N56O78S |
|---|---|
| Molecular weight | ≈4963 g/mol |
| CAS number | 77591-33-4 |
| Half-life | Not well established in humans |
| Appearance | White lyophilized powder |
| Formulation | Lyophilized Powder |
| PubChem CID | 45382195 |
Identifiers link to the public PubChem, FDA Substance Registration (UNII), ChEMBL and DrugBank records for the same entity.
Science
Mechanism of Action
Thymosin beta-4 is a 43-amino-acid peptide and the principal G-actin sequestering protein in most mammalian cells, binding monomeric actin through its LKKTETQ motif and maintaining the unpolymerised pool that cells draw on to remodel their cytoskeleton. That function underlies its effects on cell motility, since directed migration requires rapid local actin polymerisation. Beyond actin binding it has been reported to promote angiogenesis, upregulate laminin-5, downregulate inflammatory cytokines, and reduce apoptosis in injured tissue. It has been investigated in dermal, corneal and cardiac repair. It is not approved for any use and is prohibited in sport.
Origin
Endogenous 43-aa peptide; synthetic research material.
Targets
Regulatory & research status
Thymosin β4 (Tβ4) is not an FDA-approved product. It is sold for laboratory research and has no approved medical use.
| FDA status | Not Approved |
|---|---|
| Availability | Research-Only |
| WADA (sport) | Banned in Sport |
| Library classification | Research-Only |
Benefits
Thymosin β4 (Tβ4) side effects
Side Effects
- Limited human AE data for research vials
Storage & stability
Lyophilized (freeze-dried) peptide powder is far more stable than the reconstituted solution. Keep sealed vials cold, dry and away from light; long-term storage is typically frozen, with short-term refrigeration for vials in use.
Once reconstituted in bacteriostatic water, keep the solution refrigerated, avoid repeated freeze–thaw cycles and agitation, and label the vial with the reconstitution date and concentration. Discard any solution that turns cloudy or shows particulates.
Degradation rates differ by sequence: peptides containing methionine, cysteine, asparagine or glutamine are more prone to oxidation and deamidation, so shelf life after reconstitution is compound-specific rather than universal.
Read the full guide: how to store peptides before and after reconstitution →
Source: Manning MC, Chou DK, Murphy BM, Payne RW, Katayama DS. Stability of protein pharmaceuticals: an update. Pharm Res. 2010;27(4):544–575. (PMID 20143256). General guidance for research handling; not product-specific instructions.
Thymosin β4 (Tβ4): frequently asked questions
What is Thymosin β4 (Tβ4)?
43-aa G-actin-sequestering peptide studied for wound healing and cardiac repair (timbetasin programs). Not FDA-approved. Distinct from the shorter TB-500 fragment.
How does Thymosin β4 (Tβ4) work?
Thymosin beta-4 is a 43-amino-acid peptide and the principal G-actin sequestering protein in most mammalian cells, binding monomeric actin through its LKKTETQ motif and maintaining the unpolymerised pool that cells draw on to remodel their cytoskeleton. That function underlies its effects on cell motility, since directed migration requires rapid local actin polymerisation.
Is Thymosin β4 (Tβ4) FDA approved?
No. Thymosin β4 (Tβ4) is not approved by the FDA for any indication and is categorised as research-only. It has not been reviewed for safety or efficacy as a medicine, and published research should be read as investigation rather than established use.
What is the half-life of Thymosin β4 (Tβ4)?
Reported half-life for Thymosin β4 (Tβ4) is Not well established in humans. Half-life describes how long the compound persists in circulation, not how long any effect lasts, and published figures vary with route of administration, formulation and the population studied.
Is Thymosin β4 (Tβ4) banned in sport?
Thymosin β4 (Tβ4) is recorded here as prohibited in sport. Athletes subject to anti-doping rules should check the current WADA Prohibited List directly, since it is revised annually and classifications change.
What peptides are similar to Thymosin β4 (Tβ4)?
Compounds most often compared with Thymosin β4 (Tβ4) include BPC-157, TB-500 (Thymosin Beta-4 fragment), Pentadeca Arginate and GHK-Cu (Copper Peptide). They are grouped by shared mechanism or research area rather than by equivalence, and their regulatory status and evidence base differ.
References
- WADA Prohibited List 2026External reference
- Thymosin beta 4: An emerging therapeutic candidate for kidney diseases — Peptides, 2026External reference
- Tβ4-Ac-SDKP pathway: Any relevance for the cardiovascular system? — Can J Physiol Pharmacol, 2019External reference
- Thymosin beta 4 and the eye: the journey from bench to bedside — Expert Opin Biol Ther, 2018External reference
- Thymosin β4-mediated protective effects in the heart — Expert Opin Biol Ther, 2018External reference
- Cardioprotection by Thymosin Beta 4 — Vitam Horm, 2016External reference
Related research, comparisons & guides
- TB-500 Dosage: What the Fragment Is, and What the Numbers Rest On
- TB-500
- BPC-157 and TB-500 comparedComparison
- Muscle and recovery peptidesCategory
- Peptide dosage chart: dose, route and frequencyCategory
- Peptide calculator with the Thymosin β4 (Tβ4) preset
- How to store peptides before and after reconstitution
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Compiled by Peptide Library Editorial · Reviewed Aug 30, 2026 · Updated Aug 30, 2026 · Version 1
This Thymosin β4 (Tβ4) profile is compiled from published literature (5 cited studies linked above), public regulatory records and chemical registries. It describes what research reports; it is not medical advice, and nothing here is a dosing recommendation for humans. Peptide Library does not sell peptides. Editorial policy · How profiles are compiled · Report an error
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