HOME / RESEARCH PEPTIDES / TB-500
TB-500 is a synthetic seven-residue peptide, N-acetylated at its N-terminus, with the sequence Ac-LKKTETQ.1 The sequence corresponds to residues 17 to 23 of thymosin beta-4, a 43-residue protein, so TB-500 is a fragment of that protein rather than the full-length molecule.2 It is also written TB500 and TB 500.
This page is a reagent reference: identity, structure, storage, laboratory reconstitution and certificate status. It is not a product listing and makes no statement about any use of the compound.
Also searched as: TB500, TB 500, Ac-LKKTETQ, thymosin beta-4 (17–23), N-acetylated
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| Name | TB-500 |
|---|---|
| Other names and spellings | TB500, TB 500, N-acetyl-L-leucyl-L-lysyl-L-lysyl-L-threonyl-L-α-glutamyl-L-threonyl-L-glutamine |
| Compound class | Synthetic N-acetylated heptapeptide; fragment of thymosin beta-4 (residues 17–23) |
| Sequence (one-letter) | Ac-LKKTETQ |
| Sequence (three-letter) | Ac-Leu-Lys-Lys-Thr-Glu-Thr-Gln-OH |
| Molecular formula | C38H68N10O14 |
| Molecular weight | 889.0 g/mol |
| CAS number | 885340-08-9 |
| PubChem CID | 62707662 |
| Parent protein | Thymosin beta-4: 43 residues, 4963 g/mol, CAS 77591-33-4, PubChem CID 16132341 |
| Appearance | White to off-white lyophilised (freeze-dried) powder in a sealed vial. |
| Intended use | Laboratory and research use only |
Formula, molecular weight, CAS number and synonyms are PubChem reference values (CID 62707662; parent protein CID 16132341). TB-500 is not the same substance as full-length thymosin beta-4, and a document that gives a mass near 4963 g/mol describes the parent protein, not the fragment. Sources
Store the sealed vial dry, dark and frozen at −20 °C or colder (−50 to −80 °C for long-term storage), and let it warm to room temperature in a desiccator before opening.S1 The C-terminal glutamine is one of the residues the storage literature flags as prone to deamidation, which is a reason not to keep TB-500 in solution for long: split a reconstituted stock into single-use aliquots, freeze them, and do not refreeze a thawed aliquot. A missing N-terminal acetyl group lowers the observed mass by 42 Da, which is worth checking when confirming identity.
TB-500 is short and hydrophilic: two lysines, one glutamate and two threonines, with a net charge close to zero at neutral pH. Standard handling guides suggest water first for a peptide of this kind.
The concentration of a stock solution is set by the assay protocol, not by this page. Our guides to reconstituting peptides with bacteriostatic or sterile water and how to store peptides explain the reasoning behind each step.
Purity: not published. Titan Peptides publishes a purity figure only once a certificate of analysis (COA) for the batch has been checked and its compound name, CAS number and sequence match the product. Until that check is complete, no purity figure is shown on this page or in the catalogue.
A COA is available to account holders on request. Our guide on how to read a peptide certificate of analysis explains what to check, and HPLC and mass spectrometry for peptide purity covers how the figures are measured.
Schedule 4 (Poisons Standard).
In the June 2026 Poisons Standard, TB-500 and thymosin beta 4 each have their own entry in Schedule 4 (prescription-only medicines), and each is also listed in Appendix D, clause 5, which covers poisons that "must not be possessed by a person without authority".3
The TGA's 13 April 2026 safety advisory names TB-500 among its examples of unapproved peptide products and states that a "research use only" disclaimer does not make supply lawful.4 TB-500 is not an approved therapeutic good in Australia. See research peptides and Australian law.
Yes. TB500, TB 500 and TB-500 all refer to the same synthetic N-acetylated heptapeptide, Ac-LKKTETQ, CAS 885340-08-9, PubChem compound ID 62707662, with a molecular weight of 889.0 g/mol.
No. Thymosin beta-4 is a 43-residue protein of about 4963 g/mol (CAS 77591-33-4). TB-500 is a synthetic seven-residue fragment corresponding to residues 17 to 23 of that protein, acetylated at its N-terminus, at 889.0 g/mol. The two have different CAS numbers and are separate entries in the Poisons Standard.
Sealed, dry and dark at −20 °C or colder, and at −50 to −80 °C for long-term storage. Warm the vial to room temperature in a desiccator before opening. The C-terminal glutamine can deamidate in solution, so keep reconstituted stock as frozen single-use aliquots.
The expected molecular weight is 889.0 g/mol for C38H68N10O14. A result about 42 Da lighter suggests the N-terminal acetyl group is missing, and a mass near 4963 g/mol indicates full-length thymosin beta-4 rather than the fragment.
A chemical profile of TB-500, the N-acetylated LKKTETQ fragment of thymosin beta-4: identifiers, how the fragment and the full protein differ, where descriptions disagree, and how identity is checked.
A laboratory guide to storing lyophilised and reconstituted peptides: freezer temperatures, moisture, oxidation-prone residues, light, freeze–thaw cycles and adsorption to containers.
What the TGA, the June 2026 Poisons Standard, the Therapeutic Goods Act and customs law actually say about peptides, "research use only" labels, import controls and advertising in Australia.
Listed by title and journal for identification only. Titan Peptides does not summarise or rely on the findings of these papers.
