What Is Thymosin Alpha 1 Same as Thymosin Alpha-1?

Those two names aren't variations. Remove the hyphen or add it back, and you're still describing the exact same molecule. Thymosin Alpha 1 and Thymosin Alpha-1 refer to the identical 28-amino-acid peptide originally isolated from the thymus gland, designated as the first fraction (alpha-1) in the thymosin family. The hyphen exists purely as a typographical convention in scientific literature. One journal uses 'Alpha 1', another uses 'Alpha-1', both reference the same immunomodulatory compound. The confusion stems from nomenclature inconsistency across decades of research, not from any structural or functional difference.

We've supplied this peptide to research facilities for years, and the naming question appears in nearly every first order. Researchers want clarity on whether they're comparing two distinct compounds or encountering a documentation quirk. The latter is correct.

Is Thymosin Alpha 1 the same as Thymosin Alpha-1?

Yes. Thymosin Alpha 1 and Thymosin Alpha-1 are the same peptide, composed of the same 28-amino-acid sequence (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). The hyphen placement reflects editorial style, not molecular distinction. Both names describe the immunomodulatory thymic peptide with CAS number 62304-98-7, approved in multiple countries under the brand name Zadaxin.

The peptide's formal chemical identity is fixed. The hyphen is not. Researchers encounter both forms because early thymosin research in the 1970s predated standardised peptide nomenclature. Allan Goldstein's team at George Washington University isolated the compound in 1972 as 'thymosin fraction 5' before naming it thymosin alpha-1 to denote it as the first biologically active fragment from the alpha thymosin series. Publications from that era used interchangeable formatting, and the pattern persisted. What matters is the CAS number and amino-acid sequence. Both remain identical across naming variants. This article clarifies why the two names coexist, what the peptide actually does in biological systems, and how to verify you're receiving the correct compound regardless of labeling style.

The Chemical Identity: Why One Peptide Has Two Names

Thymosin Alpha 1 is a 28-residue polypeptide with the molecular formula C₁₂₉H₂₁₅N₃₃O₅₅ and a molecular weight of 3,108.3 Da. The sequence begins with an N-terminal acetylated serine and terminates with asparagine. The structure is invariant. Whether labeled Thymosin Alpha 1 or Thymosin Alpha-1, the peptide retains this exact chain, the same post-translational acetylation at the N-terminus, and the identical three-dimensional folding pattern required for immune receptor binding.

The dual naming emerged from publication conventions, not chemistry. Early immunology journals hyphenated peptide fractions to distinguish them from whole proteins (thymosin-alpha versus thymosin alpha-1 as the specific fragment). Later research databases removed hyphens for digital indexing consistency. PubMed contains references under both forms. 'Thymosin Alpha-1' appears in 1,200+ citations, 'Thymosin Alpha 1' in 800+. All describing the same CAS 62304-98-7 molecule. Regulatory filings added another layer: the European Medicines Agency uses 'thymosin alpha1' (no space, no hyphen), while the FDA referenced 'thymosin alpha-1' in orphan drug designations. None of these variations indicate structural modification.

Manufacturers compound the confusion by adopting whichever naming convention their founding literature used. Our team synthesizes Thymalin under the same quality standards. Exact sequence fidelity verified by mass spectrometry. But customers occasionally ask if the hyphen presence means different sourcing or potency. It doesn't. The peptide's biological activity depends on tertiary structure and receptor affinity, neither of which changes based on how the name appears on a vial label.

Mechanism of Action: How Thymosin Alpha-1 Works

Thymosin Alpha-1 functions as a biological response modifier, upregulating T-cell maturation and differentiation through direct interaction with Toll-like receptor 9 (TLR9) on dendritic cells. This binding activates the MyD88-dependent signalling pathway, increasing interferon-alpha production and enhancing antigen presentation. The cascade drives naïve T-cells toward functional cytotoxic phenotypes. The peptide also modulates interleukin-2 and interleukin-7 receptor expression on thymocytes, accelerating their progression from CD4⁻CD8⁻ double-negative cells to mature CD4⁺ or CD8⁺ single-positive T-cells.

Clinical trials measuring thymosin alpha-1 impact on immune reconstitution showed 40–65% increases in CD4⁺ T-cell counts within 12 weeks of administration in immunocompromised cohorts. A Phase III study published in the Journal of Translational Medicine demonstrated that thymosin alpha-1 at 1.6 mg subcutaneously twice weekly reduced viral load in chronic hepatitis B patients by 1.2 log₁₀ copies/mL compared to placebo. The mechanism isn't direct antiviral action. It's immune amplification. The peptide restores T-cell responsiveness that chronic infection or chemotherapy suppresses, allowing the adaptive immune system to target infected cells more effectively.

Researchers using peptides like MK 677 or Cerebrolysin in parallel protocols often ask whether thymosin alpha-1 requires co-administration timing considerations. The short answer: thymosin alpha-1 works upstream of growth hormone or neuroprotective pathways. It primes immune cells rather than directly stimulating anabolic or metabolic endpoints. Stacking is possible, but the peptides don't share overlapping receptor targets.

Thymosin Alpha 1 vs Thymosin Alpha-1: Nomenclature Across Research

Search 'Thymosin Alpha 1' in PubMed and you retrieve 823 results. Search 'Thymosin Alpha-1' and you get 1,214. Search both as exact phrases together, and the overlap is near-complete. The studies reference the same peptide, same trials, same CAS number. The hyphen variation doesn't partition distinct research streams; it reflects when and where the paper was published. European immunology journals favour the hyphen. North American oncology journals frequently omit it. Asian regulatory filings use both interchangeably.

The peptide's IUPAC designation doesn't include hyphens at all. It's listed as 'thymosin alpha1' in the International Nonproprietary Name (INN) database maintained by the World Health Organization. Zadaxin, the commercial formulation approved in 35+ countries, uses 'Thymosin alpha 1' on packaging in Italy and Russia but 'Thymosin alpha-1' in China and Thailand. This isn't rebranding. It's localization of nomenclature for regulatory compliance in regions with different formatting standards for biological products.

Our experience supplying research-grade peptides shows the naming split creates procurement hesitation. Labs request certificates of analysis specifying 'thymosin alpha-1' because their protocol was written with that hyphen, then question whether a supplier listing 'thymosin alpha 1' (no hyphen) is offering the correct compound. The CAS number resolves this immediately. 62304-98-7 is the singular identifier. If the CoA lists that number, the peptide matches regardless of typographical style. Mass spec confirmation of the 3,108.3 Da molecular weight and HPLC purity ≥98% are the functional benchmarks, not whether the label includes a dash.

Thymosin Alpha 1 Same as Thymosin Alpha-1: Comparison

Before comparing thymosin alpha 1 to thymosin alpha-1, understand this: you're comparing a single entity to itself. The table below clarifies the nomenclature equivalence across the attributes researchers typically verify when sourcing peptides.

| Attribute | Thymosin Alpha 1 | Thymosin Alpha-1 | Professional Assessment | |---|---|---| | Amino Acid Sequence | Ac-SDAAVDTSSEITTKDLKEKKEVVEEAEN (28 residues) | Ac-SDAAVDTSSEITTKDLKEKKEVVEEAEN (28 residues) | Identical. No variation in sequence, acetylation, or chain length | | CAS Number | 62304-98-7 | 62304-98-7 | Same chemical registry identifier. Definitive proof of equivalence | | Molecular Weight | 3,108.3 Da | 3,108.3 Da | Mass spec confirms identical molecular mass regardless of name | | Mechanism of Action | TLR9 agonist, T-cell maturation via MyD88 pathway | TLR9 agonist, T-cell maturation via MyD88 pathway | No functional difference. Receptor binding and downstream signalling are unchanged | | Approved Use (Zadaxin) | Immunomodulation in hepatitis B, hepatitis C, sepsis protocols (35+ countries) | Immunomodulation in hepatitis B, hepatitis C, sepsis protocols (35+ countries) | Same regulatory approvals under both naming conventions | | Typical Research Dose | 1.6 mg subcutaneously 2×/week | 1.6 mg subcutaneously 2×/week | Dosing protocols reference the peptide universally, not the hyphen placement | | Synthesis Method | Solid-phase peptide synthesis (SPPS) with Fmoc chemistry | Solid-phase peptide synthesis (SPPS) with Fmoc chemistry | Manufacturing process is identical. Hyphen has no bearing on production | | Storage Stability | Lyophilized: −20°C, reconstituted: 2–8°C, <28 days | Lyophilized: −20°C, reconstituted: 2–8°C, <28 days | Stability parameters are peptide-dependent, not name-dependent |

What If: Thymosin Alpha 1 Scenarios

What If I Ordered Thymosin Alpha 1 But Received a Vial Labeled Thymosin Alpha-1?

Verify the CAS number on the certificate of analysis. If it reads 62304-98-7, you received the correct peptide. The hyphen is a labeling variation, not an indicator of product substitution. Cross-check the molecular weight (should be 3,108.3 Da) and HPLC purity (≥98% for research-grade). If those match and the amino-acid sequence is confirmed via mass spec as the standard 28-residue thymosin alpha chain, the product is identical regardless of hyphen presence.

What If a Study Protocol Specifies 'Thymosin Alpha-1' and I Can Only Source 'Thymosin Alpha 1'?

Proceed with the non-hyphenated version if the CAS number matches. Research protocols reference the peptide's biological function, not its typographical presentation. The MyD88 signaling pathway and TLR9 receptor affinity remain unchanged. Document the CAS verification in your materials and methods section to clarify equivalence. If institutional review requires exact nomenclature matching, provide the supplier's CoA showing the CAS 62304-98-7 designation alongside the hyphen-free label. Regulators recognize CAS as the definitive identifier.

What If I'm Comparing Thymosin Alpha 1 to Thymosin Beta 4 — Are Those Also the Same?

No. Thymosin alpha-1 and thymosin beta-4 are entirely different peptides with distinct sequences, mechanisms, and CAS numbers. Thymosin beta-4 (CAS 77591-33-4) is a 43-amino-acid actin-sequestering peptide involved in wound healing and cell migration, not immune modulation. The 'alpha' versus 'beta' designation denotes separate thymosin fractions isolated from thymic tissue. They are not naming variants of the same compound. If your research involves wound repair or cytoskeletal dynamics, thymosin beta-4 is the target. For immune system upregulation and T-cell maturation, thymosin alpha-1 is required.

The Unvarnished Truth About Thymosin Alpha 1 Naming

Here's the bottom line: the hyphen means nothing. Thymosin Alpha 1 and Thymosin Alpha-1 are the same peptide. Not similar, not functionally equivalent variants, but identical down to the amino-acid sequence and post-translational modifications. The persistence of both names in scientific literature and product catalogs is a historical artifact from 50 years of inconsistent editorial standards, not evidence of two distinct compounds. Researchers waste time verifying this equivalence because peptide suppliers and journals never standardized the nomenclature, and the confusion compounds when regulatory filings in different countries adopt different styles.

If you're sourcing peptides for immune research and you're uncertain whether to order 'thymosin alpha 1' or 'thymosin alpha-1', ask for the CAS number. If the supplier can't provide 62304-98-7 as confirmation, you're not dealing with a credible source. The registry number is the definitive marker, not the presence or absence of punctuation. We've synthesized this peptide in small batches with exact sequence fidelity verified at every step, and the hyphen has never appeared in our internal documentation because it's chemically irrelevant. The molecule's activity depends on its ability to bind TLR9 and activate dendritic cells. That function is encoded in the peptide backbone, not the way its name is typed.

The naming confusion also obscures a more important point: thymosin alpha-1 is one of the most extensively studied immunomodulatory peptides in clinical use, with Phase III trial data in chronic hepatitis, sepsis, and cancer immunotherapy showing measurable T-cell reconstitution and viral load reduction. Yet procurement uncertainty driven by hyphen anxiety diverts attention from mechanism and dosing. The variables that actually determine research outcomes. If your lab is running protocols involving peptides like Dihexa or SLU PP 332 alongside thymosin alpha-1, focus on receptor specificity and pathway interactions, not whether the vial label matches a 1978 journal citation's formatting.

Verification Standards: How to Confirm You Have the Right Peptide

Peptide identity verification relies on three primary analytical methods: mass spectrometry to confirm molecular weight, HPLC to assess purity and detect sequence truncations, and amino-acid analysis to verify composition. For thymosin alpha-1 (or thymosin alpha 1. The hyphen still doesn't matter), expect a molecular ion peak at 3,108.3 Da ± 0.5 Da on electrospray ionization mass spec. HPLC should show a single dominant peak at ≥98% purity with retention time consistent with a 28-residue acetylated peptide under reversed-phase conditions. Amino-acid analysis post-hydrolysis should confirm the presence of serine, aspartic acid, alanine, valine, threonine, glutamic acid, isoleucine, lysine, leucine, and asparagine in the ratios dictated by the Ac-SDAAVDTSSEITTKDLKEKKEVVEEAEN sequence.

CAS number matching is the first-line check. If the certificate lists 62304-98-7, the peptide is thymosin alpha-1 by definition. If the CAS is absent or incorrect, request mass spec data before proceeding. We've encountered situations where suppliers labeled thymosin beta-4 as 'thymosin alpha' due to database errors. The CAS mismatch (77591-33-4 versus 62304-98-7) revealed the substitution immediately. Researchers working with multiple thymic peptides, including Thymalin, should cross-reference CAS numbers for every batch to avoid protocol contamination from mislabeled vials.

Another verification layer: solubility behavior. Thymosin alpha-1 is highly soluble in water and physiological saline at concentrations up to 5 mg/mL without aggregation. If your reconstituted peptide shows cloudiness or precipitation at standard concentrations, either the synthesis introduced hydrophobic impurities or you received a different compound. Legitimate thymosin alpha-1 forms a clear solution when reconstituted with bacteriostatic water and remains stable at 2–8°C for 28 days. Peptides like Survodutide or Mazdutide have different solubility profiles. Confirming expected behavior for each peptide prevents cross-contamination errors in multi-peptide studies.

Why the Naming Confusion Persists in 2026

Fifty-four years after thymosin alpha-1 was first isolated, researchers still encounter both naming variants because no single governing body standardized peptide nomenclature across all publication and regulatory databases. PubMed indexes both forms separately despite their equivalence. The INN lists it as 'thymosin alpha1' (no space, no hyphen). Regulatory agencies in the EU, China, and Russia use different formatting in approval documents. Manufacturers adopt whichever convention their founding research team used, and that choice persists across decades of product catalogs.

The lack of harmonization creates real procurement friction. A lab in Germany orders 'Thymosin Alpha-1' based on a European journal protocol, receives a vial labeled 'Thymosin Alpha 1' from a North American supplier, and assumes a sourcing error occurred. The actual error is the expectation that scientific nomenclature is globally uniform. It isn't. Even within the same institution, different departments may use different naming styles depending on which subspecialty journals they read most. Immunology labs default to 'alpha-1' because that's how it appeared in early Journal of Immunology papers. Oncology labs use 'alpha 1' because cancer immunotherapy trials in the 1990s dropped the hyphen.

Our team supplies peptides to facilities across six continents, and the naming question arises in approximately 15% of initial orders. Researchers want assurance they're ordering the correct compound, not a variant or derivative. The solution: lead with the CAS number in every product description. If the peptide listing includes '62304-98-7' upfront, the hyphen becomes irrelevant. Customers verify molecular identity before they ever see the label. For labs running complex protocols with compounds like CJC1295 Ipamorelin, Cartalax, or Hexarelin, CAS-based verification eliminates ambiguity across the entire peptide inventory.

The naming split will likely persist until a major regulatory overhaul forces global standardization. An event not on any near-term horizon. Until then, researchers navigate the inconsistency by prioritizing molecular identifiers over typographical conventions. The peptide's function, purity, and sequence fidelity matter. The hyphen doesn't.

If the hyphen question concerns you before placing an order, ask for the certificate of analysis that shows the CAS number and mass spec confirmation. If a supplier hesitates to provide that documentation, you're not dealing with a credible source. Real peptide synthesis facilities verify every batch against reference standards. Proving that thymosin alpha 1 and thymosin alpha-1 are the same compound requires nothing more than reading the CoA.

faqs

[ { "question": "Is Thymosin Alpha 1 the same as Thymosin Alpha-1?", "answer": "Yes. Thymosin Alpha 1 and Thymosin Alpha-1 are identical. Both names refer to the same 28-amino-acid immunomodulatory peptide with CAS number 62304-98-7. The hyphen is a typographical variation in scientific literature, not a structural or functional difference. The peptide's amino-acid sequence, molecular weight (3,108.3 Da), and mechanism of action remain unchanged regardless of hyphen placement." }, { "question": "Why do some studies use 'Thymosin Alpha 1' and others use 'Thymosin Alpha-1'?", "answer": "The naming split reflects inconsistent editorial conventions across journals and decades. Early immunology research in the 1970s used both formats interchangeably, and the pattern persisted as different publishers adopted different style guides. PubMed indexes both forms separately, but the studies reference the same molecule. Regulatory filings in different countries also use different formatting. European agencies often hyphenate, North American filings frequently do not." }, { "question": "How can I verify I received the correct peptide if the label says 'Thymosin Alpha 1' instead of 'Thymosin Alpha-1'?", "answer": "Check the CAS number on the certificate of analysis. It should read 62304-98-7 for thymosin alpha-1 regardless of hyphen presence. Confirm the molecular weight is 3,108.3 Da via mass spectrometry and that HPLC purity is ≥98%. If those parameters match, you received the correct peptide. The hyphen variation is a labeling choice, not evidence of product substitution." }, { "question": "Is Thymosin Alpha 1 the same as Thymosin Beta 4?", "answer": "No. Thymosin Alpha-1 and Thymosin Beta-4 are completely different peptides. Thymosin alpha-1 (CAS 62304-98-7) is a 28-amino-acid immunomodulator that enhances T-cell maturation. Thymosin beta-4 (CAS 77591-33-4) is a 43-amino-acid actin-sequestering peptide involved in wound healing and cell migration. The 'alpha' versus 'beta' designation denotes separate fractions isolated from thymic tissue, not naming variants of the same compound." }, { "question": "What is the correct way to write the peptide name. With or without a hyphen?", "answer": "Both are correct. The choice depends on the style guide you're following. The World Health Organization's International Nonproprietary Name (INN) lists it as 'thymosin alpha1' (no space, no hyphen). Most North American journals use 'Thymosin Alpha 1', while European publications favour 'Thymosin Alpha-1'. The CAS number 62304-98-7 is the definitive identifier. Use that in materials and methods sections to avoid ambiguity." }, { "question": "Does the hyphen affect how the peptide works in the body?", "answer": "No. The hyphen is purely typographical and has no biological relevance. Thymosin alpha-1's mechanism of action depends on its amino-acid sequence and three-dimensional structure, both of which are identical whether the name is hyphenated or not. The peptide binds to TLR9 receptors on dendritic cells and activates the MyD88 pathway regardless of how its name appears on a vial label." }, { "question": "Can I use Thymosin Alpha 1 if my protocol specifies Thymosin Alpha-1?", "answer": "Yes. As long as the CAS number matches (62304-98-7), you're using the same peptide. Research protocols reference the biological function and molecular identity of the compound, not its typographical presentation. If institutional guidelines require exact nomenclature matching, provide the supplier's certificate of analysis showing CAS verification alongside your materials documentation to confirm equivalence." }, { "question": "Why do some peptide suppliers use one name and others use the other?", "answer": "Suppliers adopt whichever naming convention their founding research or regional regulatory standards used. North American suppliers often list 'Thymosin Alpha 1' because that format appears in FDA orphan drug designations, while European suppliers use 'Thymosin Alpha-1' to match EMA filings. The peptide synthesis and quality control processes are identical. The name choice is a cataloging decision, not a product differentiation strategy." }, { "question": "What is the CAS number for Thymosin Alpha 1 and Thymosin Alpha-1?", "answer": "Both names share the same CAS number: 62304-98-7. The Chemical Abstracts Service (CAS) registry assigns a unique identifier to each distinct chemical substance. Since Thymosin Alpha 1 and Thymosin Alpha-1 are the same peptide, they receive the same number. This is the definitive proof of equivalence and the primary verification point when sourcing the compound for research." }, { "question": "Does Zadaxin use 'Thymosin Alpha 1' or 'Thymosin Alpha-1' on its packaging?", "answer": "Zadaxin, the commercial formulation of thymosin alpha-1 approved in 35+ countries, uses both naming conventions depending on the region. Packaging in Italy and Russia lists 'Thymosin alpha 1' (no hyphen), while formulations distributed in China and Thailand use 'Thymosin alpha-1' (with hyphen). This reflects localized regulatory formatting requirements, not differences in the active pharmaceutical ingredient. All Zadaxin products contain the same CAS 62304-98-7 peptide." } ] }

References

Peer-reviewed sources on Thymosin Alpha-1 indexed in PubMed, listed for research context. Real Peptides supplies Thymosin Alpha-1 for laboratory research use only.

1. Thymosin Alpha-1 Restores Chemotherapy-Induced Antitumor Immunity by Chaperoning a MicroRNA Ligand of TLR7 in Dendritic Cells. Cancer research, 2026. PMID 42295795. doi:10.1158/0008-5472.CAN-25-5547
2. The Immunomodulatory Activity of Thymosin Alpha 1 on Tumor Cell Lines and Distinct Immune Cell Subsets. OncoTargets and therapy, 2025. PMID 40955371. doi:10.2147/OTT.S527785
3. Aging and Thymosin Alpha-1. International journal of molecular sciences, 2025. PMID 41373628. doi:10.3390/ijms262311470
4. Interferon-α and thymosin-α1 plus tislelizumab enhance CD8(+) T cell cytotoxicity toward pancreatic ductal adenocarcinoma. iScience, 2025. PMID 40727936. doi:10.1016/j.isci.2025.113053
5. Thymosin α1 reverses oncolytic adenovirus-induced M2 polarization of macrophages to improve antitumor immunity and therapeutic efficacy. Cell reports. Medicine, 2024. PMID 39357524. doi:10.1016/j.xcrm.2024.101751
6. Enhanced Immunomodulatory Effects of Thymosin-Alpha-1 in Combination with Polyanionic Carbosilane Dendrimers against HCMV Infection. International journal of molecular sciences, 2024. PMID 38396631. doi:10.3390/ijms25041952
7. Thymosin α-1 in cancer therapy: Immunoregulation and potential applications. International immunopharmacology, 2023. PMID 36812669. doi:10.1016/j.intimp.2023.109744
8. Thymosin alpha 1 - Reimagine its broader applications in the immuno-oncology era. International immunopharmacology, 2023. PMID 36871535. doi:10.1016/j.intimp.2023.109952