Thymosin Alpha-1 vs Thymosin Beta-4: two different peptides
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Thymosin Alpha-1 and Thymosin Beta-4 are different peptides: the first is a 28-amino-acid acetylated peptide, and the TB-500 listing is a short fragment of the second. The shared word "thymosin" reflects a common origin in the naming history, not a shared structure. This guide lines up the identifiers on our listings.
The two listings at a glance
| Thymosin Alpha-1 | TB-500 | |
|---|---|---|
| Synonyms | Thymalfasin, Tα1, TA-1 | Thymosin Beta-4 Fragment, Tβ4 Fragment |
| CAS number | 62304-98-7 | 77591-33-4 |
| Sequence | Ac-Ser-Asp-Ala-Ala-Val-Asp-Thr-Ser-Ser-Glu-Ile-Thr-Thr-Lys-Asp-Leu-Lys-Glu-Lys-Lys-Glu-Val-Val-Glu-Glu-Ala-Glu-Asn-OH | Ac-Leu-Lys-Lys-Thr-Glu-Thr-Gln-OH |
| Length | 28 amino acids | 7 residues in the listed sequence |
| Molecular formula | C129H215N33O55 | Not stated on the listing |
| Molecular weight | About 3108.3 g/mol | Not stated on the listing |
| Vial sizes | 10mg | 5mg and 10mg |
| Form | White lyophilised powder | White lyophilised powder |
Why are they easy to confuse?
The names begin the same way and both listings sit close together in a catalogue. The numbers that follow the name, "Alpha-1" and "Beta-4", identify different molecules. One is described on the listing as originally characterised from a thymosin fraction preparation. The other is described as a synthetic peptide corresponding to an active fragment of Thymosin Beta-4, a naturally occurring actin-binding protein.
What does the TB-500 name refer to?
On the listing TB-500 is a fragment, so its sequence is far shorter than the full Thymosin Beta-4 protein. A fragment and its parent protein have different masses and different CAS numbers, which is why the listed sequence and number matter more than the label. A fuller comparison is in TB-500 vs Thymosin Beta-4.
Which listings contain these compounds?
| Listing | Format |
|---|---|
| Thymosin Alpha-1 10mg | One vial, 10mg |
| TB-500 | One vial, 5mg or 10mg |
| [3V] Thymosin Alpha-1 + Thymalin + MOTS-c Research Set | Three separate vials, 10mg each |
In the set, each compound stays in its own sealed vial. The MOTS-c guide covers the third compound.
What should the documentation show?
- The name, CAS number and sequence match the listing for the compound ordered.
- An HPLC purity figure for the batch.
- A mass result consistent with the stated sequence.
- Appearance recorded as a white lyophilised powder.
Batch documents are on the COAs page.
Frequently asked questions
What is the CAS number for Thymosin Alpha-1?
The CAS number listed for Thymosin Alpha-1 is 62304-98-7.
What is the CAS number for TB-500?
The CAS number listed for TB-500 is 77591-33-4.
Is TB-500 the same as Thymosin Alpha-1?
No. They have different sequences, lengths and CAS numbers. Thymosin Alpha-1 is a 28-amino-acid peptide, while TB-500 is listed as a Thymosin Beta-4 fragment.
What is the molecular weight of Thymosin Alpha-1?
The listing gives about 3108.3 g/mol, with the molecular formula C129H215N33O55.
Are the two sold together?
Not directly. Thymosin Alpha-1 appears in a three-vial set with Thymalin and MOTS-c, and TB-500 is listed separately.
All Ascend Research products are sold strictly for laboratory research use only. They are not for human or animal use, and nothing in this article is medical advice.
The Ascend Research team
