What Is Thymosin Alpha-1 (Thymalfasin)? Structure and Literature

Thymosin alpha-1 is a 28-residue peptide, acetylated at its N-terminus, with the sequence Ac-SDAAVDTSSEITTKDLKEKKEVVEEAEN, the formula C129H215N33O55, a molecular weight of about 3108.3 Da and the CAS number 62304-98-7. It was isolated from calf thymus and sequenced in 1977 [1]. Its synthetic form carries the nonproprietary name thymalfasin.

Where does it come from?

Thymosin alpha-1 is the N-terminal fragment of prothymosin alpha, a larger protein encoded by the PTMA gene. It was first purified from thymosin fraction 5, the same crude thymus extract that gave its name to the unrelated thymosin beta-4.

What does its literature cover?

Most of its literature concerns immune signaling: effects on T-cell maturation, dendritic cells and the regulation of inflammatory responses, studied in cells, animals and clinical settings abroad [2][3]. Synthetic thymalfasin is registered as a prescription medicine in several countries outside the United States and is not approved by the FDA.

What does its structure mean for testing?

The sequence is strongly acidic, with many glutamate and aspartate residues, so the peptide carries a large net negative charge at neutral pH. It contains no tryptophan, tyrosine or phenylalanine, so it absorbs weakly at 280 nanometers and HPLC methods detect it near 214 to 220 nanometers. Its identity is confirmed by mass spectrometry, where it appears as a series of multiply charged ions deconvoluted to about 3108 Da.

How should it be stored?

As a lyophilized solid, sealed and protected from moisture. Its asparagine at the C-terminus and its acidic residues make it susceptible to deamidation and other changes in solution over time.

Frequently asked questions

Is thymosin alpha-1 related to thymosin beta-4?

No. They share only the name, which comes from the thymus extract in which both were found. They have different genes, sequences and functions.

What does the "Ac-" in its sequence mean?

The N-terminal serine is acetylated, which is part of the natural structure of the peptide.

Does FLASK list Thymosin Alpha-1?

Yes, as Thymosin Alpha-1 10 mg, with sequence, formula and CAS number on the product page.