TB-500 is a synthetic seven-amino-acid peptide, Ac-LKKTETQ, taken from the actin-binding region of thymosin beta-4 with an acetyl group added to its N-terminus. It is not the full 43-residue thymosin beta-4 protein: it is a short fragment of it, and that difference shapes how it behaves in a vial.
This reference collects what a laboratory needs to know about TB-500 as a material: how its sequence behaves in the vial, what it dissolves in, how it is handled at the bench and what to do when an order arrives. Each section below has its own page.
Molecular reference
| Name | TB-500 |
|---|---|
| Also known as | TB500, Ac-LKKTETQ, N-acetyl thymosin beta-4 (17-23) |
| Sequence | Ac-Leu-Lys-Lys-Thr-Glu-Thr-Gln-OH (Ac-LKKTETQ) |
| Residues | 7 (positions 17 to 23 of thymosin beta-4) |
| Molecular formula | C38H68N10O14 |
| Molecular weight | 889.0 g/mol |
| CAS number | 885340-08-9 |
Formula, molecular weight, CAS number and the acetylated sequence are from PubChem (CID 62707662).
Three features of that sequence explain most of its behaviour. It is very short and very polar: of its seven residues only leucine is clearly hydrophobic, and it has no aromatic residue at all, so there is little to drive molecules together. It has no methionine, cysteine, tryptophan, histidine, tyrosine, asparagine or aspartic acid, so the oxidation, deamidation and aspartate routes that limit many peptides are absent; the methionine at position 6 of full-length thymosin beta-4, which oxidises to a sulfoxide (Huff et al., European Journal of Biochemistry, 1995), lies outside the fragment. And its acetylated N-terminus with two lysines next to it is where enzymes cut it in biological fluid (Rahaman et al., Journal of Chromatography B, 2024).
What it is studied for
The identity of TB-500 was settled by doping-control laboratories. A Ghent group identified Ac-LKKTETQ in a TB-500 product by high-resolution mass spectrometry and synthesised the same peptide to confirm it (Esposito et al., Drug Testing and Analysis, 2012). A Hong Kong racing laboratory described the key ingredient of the veterinary preparation in the same terms and mapped its metabolites in equine samples (Ho et al., Journal of Chromatography A, 2012).
The research interest comes from the parent protein. A review of thymosin beta-4 active sites describes the central LKKTETQ region, its actin-binding domain, as the part linked to angiogenesis, wound healing and cell migration in laboratory models (Sosne et al., FASEB Journal, 2010). In cultured human hepatic stellate cells, the 17 to 23 fragment, and not the N-terminal 1 to 15 fragment, blocked PDGF-BB driven activation, proliferation and migration (Shah et al., Expert Opinion on Biological Therapy, 2018). A 2024 study tested the fragment and its breakdown products in fibroblasts and found wound-closure activity in the metabolite Ac-LKKTE rather than in the parent peptide (Rahaman et al., Journal of Chromatography B, 2024), and a 2025 study built LKKTETQ into a self-assembling hydrogel for an animal corneal injury model (Lu et al., ACS Applied Materials and Interfaces, 2025).
Our summaries are in TB-500 vs thymosin beta-4 and BPC-157 vs TB-500.
Stability
Because its seven residues lack every residue that oxidises, deamidates quickly or isomerises, TB-500 is among the most chemically forgiving research peptides. Its practical risks in solution are enzymes from contamination, which cut it at the lysines, and surface losses at very low concentrations. The TB-500 stability page covers those routes, freeze-thaw, light and what visible changes mean.
Solubility
TB-500 is short, highly polar and free of aromatic residues, so it dissolves readily in bacteriostatic water without any acid. The TB-500 solubility guide explains why, which concentrations dissolve cleanly and what causes haze.
Handling
Bench practice for TB-500 is mostly about keeping the solution cold, sterile and labelled. The TB-500 handling page lists the steps and the common mistakes.
On arrival
What a sealed vial should look like, why it travels without an ice pack and where it goes first are on the TB-500 on-arrival page.
Storage and reconstitution
Fridge and freezer windows, before and after mixing, are on how long TB-500 lasts. Water volumes and the concentration table for a 10 mg vial are on how much bacteriostatic water for a TB-500 10 mg vial.
FAQ
Short answers to the questions researchers ask most about storing, mixing and handling TB-500 are on the TB-500 FAQ.
Where to get it
Vistara Labs supplies TB-500 10 mg as a lyophilised vial for laboratory research, shipped within Canada by Canada Post Xpresspost. A ready-mixed TB-500 Nasal Spray and the BPC-157 + TB-500 blend are also available. Certificates are on our lab reports page, and they state the identity confirmed for each batch.
All products supplied by Vistara Labs are intended for laboratory research use only. They are not drugs, are not approved for human or veterinary use, and are not intended to diagnose, treat, cure or prevent any condition. Nothing on this page constitutes medical advice or guidance for use in humans.
