Thymosin Alpha-1 — wholesale 10-vial kits

Research context

Thymosin alpha-1 was isolated from thymosin fraction 5, a bovine thymic extract, and its sequence was reported in PNAS in 1977. It corresponds to the N-terminal 28 residues of prothymosin alpha (UniProt P06454) and is generated from that precursor by a lysosomal asparaginyl endopeptidase. Common synonyms are Tα1, thymosin α1 and the INN thymalfasin; the synthetic peptide is chemically identical to the natural sequence.

Two structural features define it. The N-terminal serine is acetylated, which blocks aminopeptidase attack and removes the free alpha-amino group, so Edman sequencing is uninformative and LC-MS is the practical identity method. The sequence is also unusually acidic — rich in aspartate and glutamate with a short basic stretch in the middle — giving a low isoelectric point, high aqueous solubility and little secondary structure in water. In membrane-mimetic or crowded environments the C-terminal half shows a tendency to helix, and that region carries most of the reported immune activity in fragment studies.

At the cellular level Tα1 is studied as a modulator of innate and adaptive immune signaling rather than as a receptor-selective ligand. Work published in Blood in 2004 showed it activates dendritic cells through Toll-like receptor signaling, with TLR9/MyD88-dependent readouts and a shift in cytokine output; other cell and animal studies describe effects on thymocyte and T-cell maturation, interferon-gamma and interleukin-2 production, and natural-killer-cell activity. No single high-affinity receptor has been established, which is why the literature uses pathway-level readouts.

Laboratory use follows from that. Tα1 appears as a comparator or stimulus in dendritic-cell maturation panels, TLR reporter lines, T-cell differentiation and proliferation assays, and multiplex cytokine profiling. It is also a reference compound in thymic-peptide biochemistry, alongside thymulin and thymosin beta-4 — molecules that share the historical "thymosin" name but are structurally unrelated and should not be used interchangeably in method development. A further practical use is as a spiking standard: because the acetylated 28-mer is acidic and ionizes well in negative mode, it is a convenient system-suitability peptide for methods aimed at acidic sequences, and the fragment series derived from it is used to localize activity in structure–activity work. Analytically, it is used as an identity and quantitation standard for the acetylated 28-mer by RP-HPLC and LC-MS.

Regulatory position differs by jurisdiction and is stated here as fact only. Thymalfasin is registered as a medicine (Zadaxin) in a number of countries outside the United States, and the peptide has been the subject of randomized trials in chronic hepatitis B and in sepsis, including a Phase 3 trial reported in The BMJ in 2025. It is not FDA-approved in the United States, and FDA lists thymosin-alpha 1 among bulk drug substances whose compounding nominations were withdrawn. The material supplied by WholesalePeptide.us is a research reference standard, not a drug product.

Because the sequence is rich in glutamate and aspartate, Tα1 elutes early on reversed-phase HPLC and ionizes well in negative mode. Each lot's COA reports RP-HPLC purity and the LC-MS mass for the acetylated 28-mer.

Research areas

• dendritic-cell Toll-like receptor signaling
• T-cell maturation and differentiation
• cytokine profiling in immune-cell assays
• thymic peptide biochemistry
• acidic peptide chromatography and mass spectrometry
• prothymosin alpha processing
• N-terminal acetylation and peptide identity confirmation

U.S. regulatory status of the compound (as an active ingredient): Not FDA-approved in the U.S.; approved as thymalfasin (Zadaxin) in a number of other countries. The material sold here is a research reference chemical, not a drug product.

Handling and storage

• Store lyophilized vials at −20 °C, sealed, protected from light and moisture.
• Let the vial equilibrate to room temperature before opening to limit condensation.
• Reconstitute in an appropriate sterile buffer or solvent according to your laboratory SOP.
• Aliquot reconstituted material and avoid repeated freeze–thaw.