Peptide reference · 43-residue acetylated peptide
Thymosin Beta-4 COA check: molecular weight, formula and what to look for
Use these reference values to check the identity result on a Thymosin Beta-4 Certificate of Analysis. The theoretical average molecular weight of Thymosin Beta-4 is 4,963.44 Da and the monoisotopic mass is 4,960.486 Da.
Check a Thymosin Beta-4 COA nowThymosin Beta-4 reference data
| Name | Thymosin Beta-4 |
|---|---|
| Also known as | Tβ4, TB4, Timbetasin |
| Type | 43-residue acetylated peptide |
| Molecular formula | C212H350N56O78S |
| Average molecular weight | 4,963.44 g/mol (Da) |
| Monoisotopic mass | 4,960.4863 Da |
| Residues | 43 |
| Reference source | PubChem CID 45382195 (formula and mass cross-checked) |
Expected mass spectrometry ions
A Thymosin Beta-4 COA may list one of these m/z values instead of the neutral mass. That is still consistent with Thymosin Beta-4. How charge states work.
| Ion | m/z (monoisotopic) | m/z (average) |
|---|---|---|
| [M+3H]3+ | 1,654.50 | 1,655.49 |
| [M+4H]4+ | 1,241.13 | 1,241.87 |
| [M+5H]5+ | 993.10 | 993.70 |
| [M+6H]6+ | 827.75 | 828.25 |
What else can show up on a Thymosin Beta-4 COA
Masses calculated from Thymosin Beta-4's formula for the adducts, degradation products and synthesis impurities a lab report can show. A match tells you what the extra peak probably is.
| Signal | Value | What it means |
|---|---|---|
| Na adduct, deconvoluted (M + 21.98) | 4,982.47 Da | Sodium adduct: an MS artifact, not a separate impurity. The [M+Na]+ ion itself is at M + 22.99 |
| K adduct, deconvoluted (M + 37.96) | 4,998.44 Da | Potassium adduct: an MS artifact. The [M+K]+ ion itself is at M + 38.96 |
| TFA adduct (M + 113.99) | 5,074.48 Da | Trifluoroacetic acid from purification seen as an adduct; residual TFA salt is real vial content |
| M + 16 (oxidation) | 4,976.48 Da | Oxidation of Met |
Adduct rows are deconvoluted masses (the shift seen against [M+H]+); the singly charged [M+Na]+ ion itself sits at M + 22.99. Deletion masses alone can't say which copy of a repeated residue is missing.
At over 4 kDa, Thymosin Beta-4 is harder to purify; 98% or higher with one sharp main peak is a strong result. The full checklist is in how to read a peptide COA.
Thymosin Beta-4-specific things to watch
Full-length Thymosin Beta-4 is about 4963 Da, more than five times heavier than the TB-500 fragment. On an ESI mass spectrum it typically appears as a ladder of multiply-charged ions rather than a single peak, and the lab should report the deconvoluted mass.
Because it is a long sequence, synthesis by-products (deletion and truncated sequences) are more likely than with short peptides, so the HPLC purity figure matters more here. A COA showing a single dominant peak at 98% or higher is a good sign.
If a vendor calls this product "TB-500", make sure the COA mass is around 4963 Da and not 889 Da, and vice versa.
Compounds with similar mass
If a COA's mass is off, compare it with these neighbors. A match to one of them can point to a mislabeled product.
- Tirzepatide: 4,813.45 Da (-149.99 Da)
- Tesamorelin: 5,135.78 Da (+172.34 Da)
- Retatrutide: 4,731.35 Da (-232.09 Da)
Sources
- PubChem CID 45382195: Thymosin Beta-4 formula and reference mass.
- CIAAW: Standard atomic weights: Used to calculate average molecular weights.
- NIST CODATA: proton mass: Used to convert m/z charge states to neutral mass.
- PeptideCOACheck methodology: How the checker's thresholds work.
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Frequently asked questions
What is the molecular weight of Thymosin Beta-4?
The average molecular weight of Thymosin Beta-4 (C212H350N56O78S) is 4,963.44 Da and its monoisotopic mass is 4,960.4863 Da, calculated from the molecular formula and cross-checked against PubChem CID 45382195.
What other masses can show up on a Thymosin Beta-4 COA?
Besides the main peak, a Thymosin Beta-4 COA can show a sodium adduct (deconvoluted mass near 4,982.47 Da) and an oxidation product near 4,976.48 Da. The table on this page lists every expected variant with its mass.
For laboratory research use only. This page describes analytical chemistry data. It is not medical advice and makes no claim about effects in humans or animals.