How do I verify Thymosin Alpha-1 on a COA?

Check the mass. The N-terminal acetyl group adds 42 daltons, so a reported mass 42 Da below the expected figure describes the non-acetylated sequence — a different molecule from the one used in the published work.

Why is Thymosin Alpha-1 so water-soluble?

Its sequence is dominated by aspartate and glutamate with few basic residues. That excess of negative charge produces strong electrostatic repulsion between molecules, which keeps them dispersed and makes aggregation less likely than for a charge-balanced sequence.

Is Thymosin Alpha-1 supplied as a TFA salt?

Often not. A strongly acidic peptide is more likely to be supplied as a sodium or ammonium salt than as trifluoroacetate. The Certificate of Analysis should state the counter-ion explicitly.

Identification·2 min read

Thymosin Alpha-1 — identity and the clinical literature

A 28-residue N-acetylated thymic peptide with more clinical literature behind it than almost any compound in this market. Identity data and what the studies covered.

Thymosin Alpha-1 is a 28-residue N-acetylated peptide of thymic origin, molecular weight 3108.3 g/mol. It carries an unusually large clinical literature for a compound in this market — the studies in our library span three decades and multiple countries, which is rare and worth knowing when comparing documentation quality.

By the Bench Grade Research Team · Last updated October 7, 2026

Thymosin Alpha-1 identity data

Identity
Property	Value
Length	28 residues
N-terminus	Acetylated
Sequence	N-Ac-SDAAVDTSSEITTKDLKEKKEVVEEAEN
Class	Thymic peptide

The acetyl group is a mass check

The N-terminal acetyl group adds 42 daltons. A Certificate of Analysis reporting a mass 42 Da below the expected figure is describing the non-acetylated sequence, which is a different molecule from the one the published work used. This is the single fastest identity check available for this compound.

A strongly acidic sequence

Count the residues: the sequence is dominated by aspartate and glutamate, with relatively few basic residues. That excess of negative charge at neutral pH means strong electrostatic repulsion between molecules, which is why aqueous solubility is generally good and aggregation is less of a problem than for a balanced sequence.

It also means the counter-ion situation is inverted from the usual case. A peptide this acidic is more likely to be supplied as a sodium or ammonium salt than as a trifluoroacetate, and the COA should say which.

What the published work examined

The studies in our research library are clinical and laboratory investigations conducted between 1996 and 2025, concerning immune parameters in several patient populations. They are linked below. This compound has prior FDA warning-letter history in the research-supply market, which is context worth having when evaluating any supplier who lists it.

Documentation to expect

Mass spectrometry confirming the acetylated mass, not 42 Da lower.
The counter-ion stated, which for an acidic peptide is often not TFA.
A full 28-residue sequence on the COA rather than an abbreviation.
Per-lot testing by a named independent laboratory.

References

Primary literature for the compounds discussed above. Links open the record on PubMed.

The efficacy and safety of thymosin alpha-1 for sepsis (TESTS): multicentre, double blinded, randomised, placebo controlled, phase 3 trial Liu D, et al. BMJ. 2025. PMID 39814420 → · summary
Safety and efficacy of Thymosin alpha-1 in the treatment of hepatitis B virus-related acute-on-chronic liver failure: a randomized controlled trial Shen Y, et al. Hepatol Int. 2022. PMID 35616850 → · summary
The efficacy of thymosin alpha 1 for severe sepsis (ETASS): a multicenter, single-blind, randomized and controlled trial Wu J, et al. Crit Care. 2013. PMID 23327199 → · summary
Thymosin alpha 1 is associated with improved cellular immunity and reduced infection rate in severe acute pancreatitis patients in a double-blind randomized control study Wang X, et al. Inflammation. 2011. PMID 20549321 → · summary
The efficacy and safety of thymosin alpha-1 in Japanese patients with chronic hepatitis B; results from a randomized clinical trial Iino S, et al. J Viral Hepat. 2005. PMID 15850471 → · summary
Efficacy of thymosin alpha1 in patients with chronic hepatitis B: a randomized, controlled trial Andreone P, et al. Liver. 1996. PMID 9581695 → · summary
Orally Targeted Delivery of Tripeptide KPV via Hyaluronic Acid-Functionalized Nanoparticles Efficiently Alleviates Ulcerative Colitis Xiao B, et al. Mol Ther. 2017. PMID 28456380 → · summary
PepT1-mediated tripeptide KPV uptake reduces intestinal inflammation Dalmasso G, et al. Gastroenterology. 2008. PMID 18061177 → · summary

Primary sources

Frequently asked questions

How do I verify Thymosin Alpha-1 on a COA?: Check the mass. The N-terminal acetyl group adds 42 daltons, so a reported mass 42 Da below the expected figure describes the non-acetylated sequence — a different molecule from the one used in the published work.
Why is Thymosin Alpha-1 so water-soluble?: Its sequence is dominated by aspartate and glutamate with few basic residues. That excess of negative charge produces strong electrostatic repulsion between molecules, which keeps them dispersed and makes aggregation less likely than for a charge-balanced sequence.
Is Thymosin Alpha-1 supplied as a TFA salt?: Often not. A strongly acidic peptide is more likely to be supplied as a sodium or ammonium salt than as trifluoroacetate. The Certificate of Analysis should state the counter-ion explicitly.

Compounds discussed in this guide

Who publishes this guide

Who sells it: Bench Grade Peptides LLC, a US supplier of lyophilized synthetic peptides for laboratory research use only. It works with US manufacturing partners rather than running a facility of its own. Is Bench Grade Peptides legit? →
Certificates of Analysis: 139 third-party Certificates of Analysis covering 39 of 44 live products, published per lot in a public library anyone can read before ordering. A very recent lot can appear a few days after it enters the catalogue. COA library →
Ships from: Florida, by UPS, to US addresses only (no international shipping). The registered address in Dover, Delaware is the legal address only. Shipping →
Use: For laboratory research use only — not for human or veterinary use. Not a drug, supplement or medical device. Compliance and research use →

All products discussed in this guide are supplied by Bench Grade Peptides for laboratory research use only. Not for human or veterinary use.