Peptide reference · 28-residue N-acetylated peptide
Thymosin Alpha-1 COA check: molecular weight, formula and what to look for
Use these reference values to check the identity result on a Thymosin Alpha-1 Certificate of Analysis. The theoretical average molecular weight of Thymosin Alpha-1 is 3,108.28 Da and the monoisotopic mass is 3,106.504 Da.
Check a Thymosin Alpha-1 COA nowThymosin Alpha-1 reference data
| Name | Thymosin Alpha-1 |
|---|---|
| Also known as | Thymalfasin, Tα1 |
| Type | 28-residue N-acetylated peptide |
| Molecular formula | C129H215N33O55 |
| Average molecular weight | 3,108.28 g/mol (Da) |
| Monoisotopic mass | 3,106.5041 Da |
| Residues | 28 |
| Reference source | PubChem CID 16130571 (formula and mass cross-checked) |
Expected mass spectrometry ions
A Thymosin Alpha-1 COA may list one of these m/z values instead of the neutral mass. That is still consistent with Thymosin Alpha-1. How charge states work.
| Ion | m/z (monoisotopic) | m/z (average) |
|---|---|---|
| [M+3H]3+ | 1,036.51 | 1,037.10 |
| [M+4H]4+ | 777.63 | 778.08 |
| [M+5H]5+ | 622.31 | 622.66 |
| [M+6H]6+ | 518.76 | 519.05 |
What else can show up on a Thymosin Alpha-1 COA
Masses calculated from Thymosin Alpha-1'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) | 3,128.49 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) | 3,144.46 Da | Potassium adduct: an MS artifact. The [M+K]+ ion itself is at M + 38.96 |
| TFA adduct (M + 113.99) | 3,220.50 Da | Trifluoroacetic acid from purification seen as an adduct; residual TFA salt is real vial content |
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 3 kDa, Thymosin Alpha-1 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 Alpha-1-specific things to watch
Thymosin Alpha-1 (thymalfasin) is a 28-residue peptide acetylated at the N-terminus, about 3108.3 Da.
It is strongly acidic, so both positive and negative-mode spectra are common. Ask the lab which mode was used if the reported m/z values look unfamiliar.
It is unrelated to Thymosin Beta-4 despite the similar name. Make sure the COA's compound name and mass match the product you ordered.
Thymosin Alpha-1 contains no methionine, tryptophan or cysteine, so oxidation isn't a normal degradation route. A missing N-terminal acetyl gives a peak about 42 Da light (near 3,066.3 Da average).
In positive mode its charge ladder sits near 1,555.2 (2+), 1,037.1 (3+) and 778.1 (4+) m/z. In negative mode, which suits this acidic peptide, the 3- ion appears near 1,035.1 m/z. Thymalfasin is the generic name, and Zadaxin is a brand name for it.
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.
- Sermorelin: 3,357.88 Da (+249.60 Da)
- CJC-1295 (no DAC): 3,367.90 Da (+259.62 Da)
- CJC-1295 (with DAC): 3,647.19 Da (+538.91 Da)
Sources
- PubChem CID 16130571: Thymosin Alpha-1 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.
Last updated . Written and maintained under our editorial policy. Found an error? See corrections.
Frequently asked questions
What does 1037.1 m/z mean on a Thymosin Alpha-1 COA?
The 3+ ion of the 3,108.3 Da molecule.
Is thymalfasin the same as Thymosin Alpha-1?
Yes. Thymalfasin is the generic name for the same 28-residue acetylated peptide.
What does a Thymosin Alpha-1 result near 3,066 Da mean?
The N-terminal acetyl group is missing (about 42 Da).
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.