Thymosin alpha-1 is a 28-residue peptide first isolated from calf thymus by Goldstein and colleagues, who published its sequence in 1977. It is acetylated at the N-terminus and ends in an asparagine, has a mass of 3108.3 and a formula of C129H215N33O55, and is sold here as a 10 mg lyophilized vial with a certificate for the lot. Its generic name is thymalfasin.
This post reads that certificate line by line and sets out what the sequence means for handling. The thymosin alpha-1 versus thymalin post covers the comparison people most often draw, and the thymalin versus thymulin post deals with the other name in that pair. This page stays with one lot of one compound.
What is in the 28 residues?
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. Written in single letters, Ac-SDAAVDTSSEITTKDLKEKKEVVEEAEN.
Three features decide its behaviour.
| Feature | Count | Consequence |
|---|---|---|
| Acidic residues, aspartate and glutamate | 10 | Net charge near minus 5 at neutral pH, with the acetylated N-terminus adding no positive charge: a strongly anionic, highly soluble peptide |
| Lysines | 5 | The only positive charges; the molecule is a polyanion with a few cationic sites |
| Cysteine, methionine, tryptophan | 0 | No oxidation or light problem; the main slow degradation route is deamidation at the C-terminal asparagine |
There is no aromatic residue at all, so the peptide does not absorb at 280 nm and cannot be quantified by A280. Purity is measured at 214 nm, where the peptide bond absorbs, which is standard for the catalogue and explained in the area-percent post.
What does lot TA110-0803 report, line by line?
The certificate is COA7585, issued by Bioviridian Inc. on 17 August 2026. Five tests.
| Test | Method | Result | What it establishes |
|---|---|---|---|
| Identity | LC-MS/MS | 3108.3 observed | The intact peptide has the predicted mass and its fragment ladder fits the sequence |
| Purity | RP-HPLC, 214 nm | 99.78% | 99.78% of the UV-absorbing area is the main peak, retention 9.31 minutes |
| Content | Gravimetric against label | 10.87 mg | Nine percent over the 10 mg label |
| Endotoxin | LAL | < 0.05 EU/mL | Below the reporting limit at the dilution tested |
| Heavy metals | ICP | < 0.01 ppm | Below the reporting limit |
Each line can be checked against the laboratory's own copy using the verification code printed on the certificate, from the COA library.
Why does 3108.3 settle the identity?
Because a 28-residue peptide has a mass that very few other things share, and because the method is tandem MS. A single mass of 3108.3 already rules out the deletion sequences a synthesis of this length produces, each of which is lighter by one residue; the smallest residue here, alanine, would take 71 off. Tandem MS goes further by fragmenting the ion and reading the ladder of fragment masses, which is sequence-dependent. The LC-MS post explains what the method adds over a single mass, and the sequence verification post covers the methods that would go further still.
The retention time, 9.31 minutes, is consistent with a peptide of this size and composition: long enough to be well retained and cleanly separated from its deletion sequences, which is what makes the purity figure discriminating.
How many micromoles is 10 mg?
The label's 10 mg at 3108.3 g/mol is 3.22 micromoles; the measured content, 10.87 mg, is 3.50. Dissolved in 1 mL that is a stock near 3.2 millimolar. For in-vitro work at the micromolar concentrations typical of the published cell assays, one vial is thousands of wells. The concentration table has the dilutions and the molarity post the method. At the listed price of $125 the vial is about $39 per micromole, which the vial-size post puts in context against the rest of the catalogue.
What does the charge mean on the bench?
- Solubility. Immediate in water or buffer. A polyanion of this kind has no tendency to aggregate at neutral pH.
- pH. With ten carboxylates, the peptide's own solution is acidic. Buffer the working stock; the pH and buffer post covers the choice.
- Adsorption. Anionic peptides bind less to the usual plastics than cationic ones do, but at the nanomolar end low-binding tubes are still the rule; the adsorption post explains why.
- Degradation. No oxidation routes. The C-terminal asparagine can deamidate slowly, faster at alkaline pH and warm; keep stocks cold and near neutral. The reconstituted shelf-life post has the general rules.
- Storage. Lyophilized at minus 20 °C. Solutions aliquoted and frozen, thawed once.
- Diluent. Water or buffer. Reconstitution solution only for a preserved multi-entry stock, as the diluent post explains.
What is its regulatory status?
Two facts, both checkable. Thymalfasin is not an approved drug in the United States; the FDA has not granted it a marketing approval. It is a marketed prescription medicine in a number of other countries, where it has carried a brand name for many years.
The vial sold here is the research-grade peptide with the certificate above, for laboratory research use only and not for human or animal use. This site states the regulatory position on the product page rather than leaving it to be discovered, for the same reason it does so for melanotan-1: a buyer is entitled to know whether the molecule in a research vial is a medicine somewhere else. The research-use post explains the designation.
Frequently asked questions
Is thymosin alpha-1 the same as thymalin?
No. Thymosin alpha-1 is a defined 28-residue peptide of mass 3108.3. Thymalin is the name of a thymus extract, and the catalogue vial sold under that name has a certificate mass of 858.8. The comparison post and the thymalin versus thymulin post cover both.
Why is the N-terminus acetylated?
Because the natural peptide is. Goldstein's 1977 isolation reported the blocked N-terminus, and synthetic thymalfasin reproduces it. The acetyl group removes the N-terminal positive charge and protects against aminopeptidases.
Can it be quantified by A280?
No. There is no tyrosine, tryptophan or cystine in the sequence. Use mass, or the content figure on the certificate; the A280 post explains which peptides the method suits.
What is the retention time telling me?
That a 3.1 kDa peptide with this composition was well retained on the column, 9.31 minutes into the run, which gives the purity figure room to be meaningful. The chromatogram post covers how to read it.
Is the vial a medicine?
No. It is the research reagent. The same peptide is a medicine in other countries under the name thymalfasin, and is not FDA-approved in the United States. What is sold here is for laboratory research use only.
References
- Goldstein AL, Low TL, McAdoo M, et al. Thymosin alpha1: isolation and sequence analysis of an immunologically active thymic polypeptide. Proceedings of the National Academy of Sciences 1977;74(2):725-729. doi.org/10.1073/pnas.74.2.725
- PubChem, National Library of Medicine. Thymalfasin, CID 16130571, C129H215N33O55, CAS 62304-98-7. Read 2 October 2026. pubchem.ncbi.nlm.nih.gov/compound/16130571
- Bioviridian Inc. Certificate of analysis COA7585, lot TA110-0803, issued 17 August 2026. Verification code on the certificate. bioviridians.com/coa-search.html
Every product mentioned is sold for laboratory research use only and is not for human or animal use. Nothing on this page describes or recommends use of the material sold here in humans or animals.
