The molecule: structure and chemistry
Thymosin alpha-1 is a small, acidic, N-acetylated peptide that is largely disordered in water and folds into a partial…
Twenty-eight acidic residues with an acetyl cap
Thymosin alpha-1 is a small, acidic, N-acetylated peptide that is largely disordered in water and folds into a partial helix only when it meets a membrane or partner. Its chemistry, not a single receptor, is the key to its pleiotropic behavior.
This unit walks the structure: the 28-residue sequence, the acetyl cap, the acidic character, the helix-versus-coil conformation, and why being a fragment of prothymosin alpha shapes how the molecule is understood and made.
Key terms
Reading the 28-residue sequence
Tα1 is a chain of 28 amino acids, unusually rich in the acidic residues aspartate and glutamate. The front end is capped with an acetyl group and the back end is a free acid. Rather than list all 28, it helps to see the landmark residues that define its behavior.
The takeaway is compositional. A chain this acidic and this short stays highly soluble and flexible in water and does not fold into a stable globular shape. That flexibility is not a flaw; it is central to how a single small peptide can interact with several different partners.
AdvancedThe full sequence, for reference
The 28-residue sequence (N to C) is 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. Count the aspartates and glutamates and the acidic character is obvious. The widely cited molecular weight near 3108 Da comes from pharmacology datasheets rather than one primary abstract, so it is best treated as a nominal value.