What is thymosin alpha-1?

Thymosin alpha-1 (Tα1) is a 28-residue N-terminally acetylated acidic peptide originally isolated from calf thymus by Allan Goldstein and colleagues in 1977. It is generated endogenously by proteolytic processing of the 109-residue precursor protein prothymosin alpha (PTMA). The peptide has substantial immunomodulatory effects mediated principally through engagement of Toll-like receptor 2 and Toll-like receptor 9, with downstream effects on dendritic-cell biology and on T-cell development and differentiation.

Who discovered thymosin alpha-1?

Thymosin alpha-1 was isolated and characterized by Allan Goldstein and colleagues, working at George Washington University. Goldstein had been studying thymic extracts since the 1960s and had developed a partially purified preparation called 'thymosin fraction 5' that had biological activity in T-cell-development assays. The isolation, sequence determination, and identification of Tα1 as one of the active components of fraction 5 was published in 1977 and represented a major milestone in the broader thymic-peptide research field.

What is prothymosin alpha?

Prothymosin alpha (PTMA) is the 109-residue intrinsically disordered acidic protein from which thymosin alpha-1 is generated by proteolytic processing. The full prothymosin alpha protein is widely expressed across tissues (not exclusively in the thymus, despite the historical name) and has multiple characterized intracellular functions including roles in chromatin biology, in apoptosis regulation, and in oxidative-stress responses. The proteolytic processing to release Tα1 has been characterized in part as occurring during apoptosis through caspase-mediated cleavage.

The molecular mechanism of Tα1's immunomodulatory effects has been substantially clarified over the past two decades through work characterizing the peptide as a ligand for Toll-like receptor 2 (TLR2/TLR6 heterodimer) and Toll-like receptor 9 (TLR9). The TLR engagement triggers MyD88-dependent signaling, NF-κB and MAPK pathway activation, and downstream effects on dendritic cell maturation and on T-cell development and differentiation. This TLR mechanism connects Tα1 to the broader pattern-recognition-receptor immunology landscape and distinguishes it from many of the older proposed mechanisms in the field.

Is Tα1 an approved medicine?

Tα1 is approved as a medicine in over thirty countries — predominantly in Asia (notably China and various Southeast Asian countries) and in parts of Europe and South America — typically marketed under the trade name Zadaxin or related names. Approved indications vary by jurisdiction but commonly include chronic viral hepatitis (hepatitis B and hepatitis C), various oncology indications, and immunocompromised-host contexts. Notably, Tα1 is not approved by the FDA in the United States. The research-peptide form sold in research-supply channels is supplied for laboratory and analytical use only, independent of the medicine approvals in other jurisdictions.

What is the molecular weight of Tα1?

Thymosin alpha-1 has a molecular formula of C129H215N33O55 (with N-terminal acetylation) and a molecular weight of approximately 3108 daltons. The peptide is 28 residues long with no modifications beyond the N-terminal acetylation, no disulfide bonds, and a strongly acidic isoelectric point reflecting the eight glutamate and five aspartate residues partially offset by four lysines.

Why is Tα1 so acidic?

The amino acid composition includes eight glutamate residues and five aspartate residues — thirteen acidic side chains in a 28-residue peptide — with four lysines providing some compensating positive charge. The net charge at physiological pH is approximately -9, and the isoelectric point is well below physiological pH. This strongly acidic character is shared with the parent prothymosin alpha protein and is one of the distinctive features of the broader prothymosin/parathymosin family.

What is the connection to apoptosis?

Published research has characterized the proteolytic processing of prothymosin alpha to generate Tα1 as occurring at least in part during apoptosis through caspase-mediated cleavage. The released Tα1 then functions as a soluble extracellular mediator. The apoptosis connection has been one of the conceptual bridges that integrates the modern mechanism story of Tα1 with broader cellular biology — the peptide can be understood in part as a damage-associated molecular pattern released during regulated cell death, which fits with its characterization as a TLR ligand.

How is Tα1 used in clinical research?

Tα1 has been investigated in clinical-research contexts for chronic viral hepatitis (hepatitis B and hepatitis C, the major historical clinical-development indications), for various oncology contexts (including hepatocellular carcinoma, melanoma, and others), for immunocompromised-host contexts (including post-chemotherapy and post-transplant settings), and (notably during 2020-2022) for COVID-19. The clinical research is conducted under appropriate regulatory frameworks in the jurisdictions involved. The educational reference here describes published research findings; the research-peptide form is supplied for laboratory work only.

What does the TLR2/TLR9 mechanism actually do?

Tα1 engagement of TLR2 (typically as the TLR2/TLR6 heterodimer) and TLR9 triggers MyD88-dependent signaling cascades — IRAK4, IRAK1, TRAF6, IKK complex activation, NF-κB nuclear translocation, MAPK pathway activation — that drive the transcriptional responses characterizing dendritic cell maturation and the downstream T-cell-development effects. The TLR9 engagement is unusual because TLR9 is canonically a nucleic-acid sensor (recognizing unmethylated CpG DNA motifs) and Tα1 represents a peptide ligand for this normally nucleic-acid-binding receptor; the molecular details of the peptide-TLR9 interaction have been characterized in published research.

How is Tα1 different from thymosin beta-4?

The two share the historical 'thymosin' name from the original Goldstein thymosin fraction 5 work, but they are structurally and functionally very different. Thymosin alpha-1 is a 28-residue acidic immunomodulatory peptide engaging TLR2/TLR9 signaling. Thymosin beta-4 is a 44-residue actin-sequestering peptide of the β-thymosin family with very different biology centered on intracellular actin dynamics, tissue-repair-research effects, and the source of the TB-500 research peptide. The shared name reflects historical co-isolation rather than molecular or biological relationship.

Zadaxin is the principal trade name under which synthetic thymosin alpha-1 is marketed as an approved medicine in the over-thirty international jurisdictions where it has regulatory approval. The active ingredient (sometimes designated thymalfasin in regulatory documents) is synthetic Tα1 produced by chemical synthesis with sequence identical to the natural calf-thymus-derived peptide. The brand and the approved indications vary by jurisdiction.

Why is Tα1 not approved by the FDA?

Multiple clinical trials of Tα1 in hepatitis C (the principal historical US-development indication) did not achieve the regulatory endpoints required for FDA approval. The trials produced mixed results — with some showing efficacy and others not — and the overall data package did not support FDA approval. The peptide is approved in over thirty other countries where the regulatory standards and the clinical-evidence base have been adequate for approval, but the specific path to FDA approval in the US has not been completed.

How is Tα1 manufactured?

Research-grade Tα1 is produced by standard solid-phase peptide synthesis using Fmoc protecting-group chemistry. The 28-residue length and the absence of unusual modifications (only the N-terminal acetylation) make the synthesis straightforward. The crude peptide is purified by reversed-phase HPLC and characterized by mass spectrometry. Reputable suppliers report purity in the 95-99% range for research-grade material. The same chemical-synthesis approach is used for the pharmaceutical-grade material marketed as Zadaxin and related approved medicines in the international jurisdictions where the peptide is approved.

What storage practices apply?

Lyophilized Tα1 stored sealed at -20 °C or below away from light and moisture is generally considered stable for extended periods. The peptide has no methionine, no cysteine, and no aromatic residues — the most chemically vulnerable amino acid side chains — and the strongly acidic character contributes to chemical stability. Reconstituted material in sterile aqueous solvent is typically held cold and used within weeks to months depending on the specific research application.

What is the connection to Aspergillus research?

The Romani group in Perugia has published extensively on Tα1 in the context of Aspergillus infection research, including characterization of the peptide's effects on antifungal immunity, on dendritic-cell-mediated antifungal responses, and on the integration with the broader antifungal-immunity landscape. The Aspergillus-research context has been one of the more active sub-areas of contemporary Tα1 mechanism research and has contributed substantially to the development of the TLR-mediated mechanism story.

What was the COVID-19 research interest?

During 2020-2022, Tα1 was investigated in various COVID-19-related clinical-research and laboratory studies in the international jurisdictions where the peptide is approved as a medicine, motivated by the proposed immunomodulatory mechanism and by the potential applicability to severe COVID-19 immunopathology. Various clinical-research reports were published from China, Italy, and other countries; the data quality and the regulatory positioning varied. The COVID-19 research did not change the FDA regulatory status in the United States.

What is the role in oncology research?

Tα1 has been investigated in oncology-research contexts including hepatocellular carcinoma (connecting to the hepatitis-related immunological background), melanoma, and various other cancer types. The mechanism connection involves the TLR-mediated effects on dendritic cell biology and on T-cell differentiation that can contribute to antitumor immunity. The clinical-research development in oncology has been part of the broader international clinical-development footprint of the peptide.

Thymosin Alpha-1 (with Bacteriostatic Water) lyophilized vial with bacteriostatic water for research

Swiss-SourcedPharmaceutical-GradeLyophilized PowderIn Stock≥99% Purity

In Stock

Thymosin Alpha-1 (with Bacteriostatic Water)

In Stock — ships from Jacksonville, FL

Free shipping over $300 — you're $300.00 away

SKU: FC7692

$97.00

Volume pricing

·10 mg

Sitewide sale price — extra discount by quantity on this line

Quantity	Price / Unit	Discount
5–9	$92.15	5%
10–15	$87.30	10%
16–20	$82.45	15%
21+	$77.60	20%

Dosage10 mg

100% Satisfaction Guarantee — damaged, incorrect, or off-spec orders are made right with a free reship or refund.
Flat-rate 2-day shipping (when available) from Jacksonville, FL · free shipping insurance on every order · free over $300.
Bacteriostatic water included — the correct amount for reconstitution, in every order.
Sourced direct from our Swiss pharmaceutical-grade manufacturer · Batch-traceable · Veteran-owned · 20% of profits donated to animal charities.
Secure checkout — powered by Shopify.

Accepted:

ZelleStripeBankful

Research use only — not for human or veterinary consumption.

What you receive

Sealed, lyophilized vial — 10 mg
Bacteriostatic water — appropriate size for reconstitution, included free
Certificate of Analysis available — view COAs

Thymosin Alpha-1 (Tα1) is a naturally occurring peptide originally isolated from the thymus gland and widely studied for its role in immune system regulation, cellular signaling, and host defense mechanisms. As one of the most extensively researched thymic peptides, Thymosin Alpha-1 has become a significant focus in immunology, infectious disease, and immune-aging research. Manufactured to rigorous laboratory standards, our Thymosin Alpha-1 research peptide undergoes comprehensive quality testing to ensure purity, consistency, and reliability for scientific investigation.

Thymosin Alpha-1 peptideTα1 peptidethymic peptide researchimmune system research peptideimmunomodulatory peptideT-cell research compoundcytokine signaling peptidelaboratory grade Thymosin Alpha-1immune aging research peptidethymosin alpha peptide

Swiss-sourced · Pharmaceutical-grade · Cold-chain shipped

What researchers say

Real reviews from Dr Jays Peptides customers

Why Dr Jays vs. the alternatives

An honest side-by-side for researchers who care about what's in the vial

Purity guarantee

Dr Jays

98%+ guaranteed

Others

95–97% claimed

COA included with every order

Dr Jays

Others

Refund if purity fails

Dr Jays

Others

Same-Day shipping UPS

Cold storage — temperature controlled

Dr Jays

Others

Responsive human support

email reply in under 30 minutes

Dr Jays

Others

100% American made & sourced

Synthesized & fulfilled in the USA

Dr Jays

Others

Veteran owned & operated

Dr Jays

Others

Criteria	Dr Jays Peptides	Other peptide vendors
Purity guarantee	98%+ guaranteed	95–97% claimed
COA included with every order		~
Refund if purity fails
Same-Day shipping UPS Cold storage — temperature controlled
Responsive human support email reply in under 30 minutes		~
100% American made & sourced Synthesized & fulfilled in the USA
Veteran owned & operated