Short regulatory and thymic peptides
Thymosin beta-4 (TB-500)
Thymosin beta-4 is a 43-residue, N-terminally acetylated peptide and the main G-actin-sequestering peptide in many cells; "TB-500" is the name used by some suppliers for synthetic material related to it.
- TypePeptide
- FormulaC212H350N56O78S
- Average mass4963.44 g/mol
- Vesta listings5
Reference page for laboratory use · updated 2026-10-30
Overview
Thymosin beta-4 (TB-500) at a glance
Thymosin beta-4 has been studied for several decades, and the literature includes methods chapters, tissue-expression reviews and papers on how to quantify it in blood reliably.
The name TB-500 is used in the market for a synthetic peptide derived from thymosin beta-4. Depending on the supplier it can mean the full-length 43-residue peptide or the shorter active-region fragment Ac-LKKTETQ (residues 17-23). The two have very different masses, so the batch documents must state which was supplied.
Structure
Full-length thymosin beta-4 has the sequence Ac-SDKPDMAEIEKFDKSKLKKTETQEKNPLPSKETIEQEKQAGES. The 17-23 fragment is a heptapeptide with an N-terminal acetyl group.
Identity
Identity data
| Name | Thymosin beta-4 (TB-500) |
|---|---|
| Also written as | TB-500, TB500, Tβ4, Thymosin beta 4 |
| Type | Peptide |
| Research area | Short regulatory and thymic peptides |
| Molecular formula | C212H350N56O78S |
| Monoisotopic mass | 4960.4863 Da |
| Average molecular weight | 4963.44 g/mol |
| Sequence | Ac-SDKPDMAEIEKFDKSKLKKTETQEKNPLPSKETIEQEKQAGES |
| PubChem record | CID 45382195 |
| TB-500 as the 17-23 fragment (Ac-LKKTETQ) | C38H68N10O14 · average 889.01 g/mol · monoisotopic 888.4916 Da |
The formula was calculated independently from the written sequence and matches the PubChem record exactly. Reference data retrieved on 2026-10-30. Compare these values with the batch certificate of analysis, using the compound identity file template.
Expected values
Mass spectrometry reference
Ions calculated from the monoisotopic mass 4960.4863 Da. Use them to check an LC-MS result; for larger peptides the instrument usually reports a deconvoluted mass close to 4963.4 Da instead.
| Ion | m/z |
|---|---|
| [M+3H]3+ | 1654.5027 |
| [M+4H]4+ | 1241.1289 |
| [M+5H]5+ | 993.1045 |
| [M+6H]6+ | 827.7550 |
For molecules of this size the tallest isotope peak is one to two mass units above the monoisotopic peak. Read the guide to average and monoisotopic mass for how these values are calculated.
Quality
Analytical notes for batch documents
- Confirm identity by intact mass. The full-length peptide is about 4963 Da, the fragment about 889 Da.
- It contains one methionine (position 6), so look for a sulfoxide at +15.995 Da.
- Mass shifts to look for in this sequence: methionine oxidation (+15.995 Da); deamidation of Asn or Gln (+0.984 Da).
- The molecular weight of a vial of powder includes counter-ions and water; the share of the powder that is peptide is the net peptide content.
Terms used on this page: Peptide.
Vesta listings
Thymosin beta-4 (TB-500) formats and prices
| Product | Per vial | SKU | Price per kit | Price per vial |
|---|---|---|---|---|
| TB500 | 5 mg | TB5 | $113.81 | $11.38 |
| TB500 | 10 mg | TB10 | $197.76 | $19.78 |
| TB500 | 20 mg | TB20 | $354.48 | $35.45 |
Research blends that contain Thymosin beta-4 (TB-500)
| Product | Per vial | SKU | Price per kit | Price per vial |
|---|---|---|---|---|
| GLOW | 70 mg | Glow70 | $208.96 | $20.90 |
| Klow | 80 mg | Klow80 | $253.73 | $25.37 |
Prices are per kit of 10 vials in US dollars. Shipping is paid by the customer and is shown in the cart. Volume savings of 5 %, 8 % and 10 % apply from $350.00, $600.00 and $1,000.00. See the full price list.
Published literature
Selected scientific literature
Bibliographic details were read from PubMed on 2026-10-30. The papers are listed for scientific reference; Vesta makes no claim about the use of its research materials in people or animals.
- Thymosin beta 4Low TL, Goldstein AL · Methods Enzymol · 1985 · PMID 4088087
- Sources of variability in quantifying circulating thymosin beta-4: literature review and recommendationsTan WKY, Purnamawati K, Pakkiri LS et al. · Expert Opin Biol Ther · 2018 · PMID 29502471
- Thymosin β(4) and β(10) Expression in Human Organs during Development: A ReviewFaa G, Messana I, Coni P et al. · Cells · 2024 · PMID 38994967
Questions
Frequently asked questions
What is Thymosin beta-4 (TB-500)?
Thymosin beta-4 is a 43-residue, N-terminally acetylated peptide and the main G-actin-sequestering peptide in many cells; "TB-500" is the name used by some suppliers for synthetic material related to it.
What is the molecular weight of Thymosin beta-4 (TB-500)?
Thymosin beta-4 (TB-500) has the formula C212H350N56O78S, an average molecular weight of 4963.44 g/mol and a monoisotopic mass of 4960.4863 Da. A salt form, a different counter-ion or a metal complex changes the molecular weight printed on a certificate of analysis, so compare like with like.
How can I check the identity of a batch of Thymosin beta-4 (TB-500)?
Compare the intact mass measured by LC-MS with the expected values on this page, for example [M+4H]4+ at m/z 1241.1289. Confirm that one main HPLC peak carries that mass and that the batch code on the report matches the vial. The guides on mass spectrometry and on certificates of analysis explain each step.
Which Thymosin beta-4 (TB-500) products does Vesta list?
Vesta lists 5 products for Thymosin beta-4 (TB-500): 5 mg, 10 mg, 20 mg per vial in kits of 10 vials, plus 2 research blends that contain it. Prices are shown per kit in US dollars, and shipping is paid by the customer.
Is TB-500 the same as thymosin beta-4?
Not necessarily. TB-500 is a trade name used for synthetic material related to thymosin beta-4. Some suppliers use it for the full 43-residue peptide and others for the short fragment Ac-LKKTETQ. The molecular weight on the certificate of analysis shows which one it is: about 4963 Da for the full-length peptide and about 889 Da for the fragment.