Thymosin Alpha-1 Molecular Weight, Sequence & CAS Reference

Chemical Identification and Structural Profile

Thymosin Alpha-1 (also designated as Ta1) is an endogenous peptide fragment originally isolated from bovine thymus tissue (Thymosin Fraction 5) and now produced via solid-phase peptide synthesis (SPPS) for highly controlled research applications. The synthetic primary sequence corresponds to the naturally occurring 28-residue peptide, featuring an acetylated N-terminus that confers structural stability against immediate aminopeptidase cleavage in enzymatic assays.

In chemical registries, Thymosin Alpha-1 is assigned the CAS Registry Number 62304-98-7. Its chemical name according to IUPAC nomenclature is N-acetyl-L-seryl-L-alpha-aspartyl-L-alanyl-L-alanyl-L-valyl-L-alpha-aspartyl-L-threonyl-L-seryl-L-seryl-L-alpha-glutamyl-L-isoleucyl-L-threonyl-L-threonyl-L-lysyl-L-alpha-aspartyl-L-leucyl-L-lysyl-L-alpha-glutamyl-L-lysyl-L-lysyl-L-alpha-glutamyl-L-valyl-L-valyl-L-alpha-glutamyl-L-alpha-glutamyl-L-alanyl-L-alpha-glutamyl-L-asparagine. Researchers can view specific lot verification data on our all-peptides analytical index.

The molecular formula of free-base Thymosin Alpha-1 is C129H215N33O45. Because of the presence of multiple ionizable side chains—specifically six glutamic acid residues, four aspartic acid residues, and four lysine residues—the overall charge state of the molecule varies significantly based on environmental pH, influencing its solubility parameters and secondary structure configuration in laboratory reagents.

Amino Acid Sequence and Primary Structure Analysis

The complete 28-amino acid sequence of Thymosin Alpha-1 is presented in standard single-letter and three-letter amino acid notation below:

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-OH (Single-letter code: Ac-SDAAVDTSSEITTKDLKEKKEVVEEAEN-OH).

A notable feature of this primary structure is the dense clustering of acidic residues (glutamic acid and aspartic acid) alongside basic residues (lysine). Out of 28 total residues, 10 carry negative charges at physiological pH (pH 7.4), while 4 carry positive charges, giving the net uncountered peptide a strongly acidic overall isoelectric point (pI) calculated at approximately 3.8 to 4.0. In vitro structural studies indicate that while Thymosin Alpha-1 lacks rigid tertiary folding in pure aqueous solution, it adopts amphipathic alpha-helical conformations upon interaction with fluorinated alcohols, membrane-mimicking micelles, or target receptor interfaces.

Molecular Weight Determination and Mass Spectrometry

The precise molecular weight calculation for Thymosin Alpha-1 is vital for determining accurate molar concentrations in benchtop research. Based on standard atomic weights (C = 12.011, H = 1.008, N = 14.007, O = 15.999), the exact monoisotopic mass and average molecular mass are calculated as follows:

Monoisotopic Mass: 3106.51 Da | Average Molecular Weight: 3108.37 g/mol. In commercial research manufacturing, small batch variations in counterions or hydration levels do not alter this baseline chemical mass, but they do affect gross vial weight.

High-performance liquid chromatography (HPLC) paired with electrospray ionization mass spectrometry (ESI-MS) is the standard method for establishing identity and purity. Due to the high molecular weight of ~3108.37 g/mol, ESI-MS spectra typically exhibit multiple charge states, such as [M+3H]3+ at m/z ~1037.1 and [M+4H]4+ at m/z ~778.1. Laboratory scientists purchasing thymosin alpha-1 5mg should evaluate the mass-to-charge ratios provided on batch documentation to confirm sequence fidelity.

Peptide Salt Forms: Trifluoroacetate (TFA) vs. Acetate Counterions

During solid-phase synthesis, peptides are cleaved from resins using trifluoroacetic acid (TFA). Consequently, raw synthetic peptides naturally exist as TFA salts. For sensitive cell culture models or in vitro enzymatic assays, residual TFA can introduce cellular toxicity or alter local buffer pH. To mitigate this, high-grade research preparations undergo salt exchange procedures to convert the compound into an acetate salt form.

The choice of salt form impacts the overall gross mass of the lyophilized material. A molecule of Thymosin Alpha-1 contains four basic lysine side chains plus the unblocked C-terminus, allowing it to associate with up to 4 to 5 counterion molecules. In a TFA salt preparation, counterions account for a substantial percentage of total vial mass. In an acetate salt preparation, the smaller molecular weight of acetate (59.04 g/mol versus TFA's 114.02 g/mol) lowers the non-peptide mass fraction significantly.

Regardless of whether TFA or acetate counterions are present, researchers must account for both residual salt and bound water (hydration) when preparing molar solutions. Further technical details regarding counterion impacts are addressed in our educational overview of peptide purity and counterions.

Calculating Net Peptide Content for Quantitative Assays

Net Peptide Content (NPC)—distinct from chemical purity percentage—represents the actual mass proportion of target peptide relative to counterions, residual moisture, and trace organic volatiles within a lyophilized cake. While HPLC purity measures the ratio of intact Thymosin Alpha-1 to peptide impurities (typically >98%), the NPC indicates what fraction of the total weighed material is truly the 3108.37 g/mol peptide chain.

For example, a lyophilized vial containing a gross mass of 5.0 mg of powder with an HPLC purity of 98.5% and a Net Peptide Content of 80% contains exactly 4.0 mg of active Thymosin Alpha-1 peptide sequence. The remaining 1.0 mg consists of bound acetate counterions and structural water molecules. When preparing stock solutions for quantitative binding or enzymatic assays, weighing uncorrected gross powder leads to systematic under-dosing of the research compound.

To ensure experimental reproducibility, investigators should consult the lot-specific Certificate of Analysis via our dedicated COA lookup hub to retrieve the verified Net Peptide Content before calculating final molarities.

Solubility Dynamics and Reconstitution Protocols

Due to its strongly acidic pI (~3.9) and high proportion of dicarboxylic amino acid residues (Glu, Asp), Thymosin Alpha-1 exhibits distinct solubility characteristics compared to basic or hydrophobic peptides. Lyophilized Thymosin Alpha-1 dissolves rapidly in sterile bacteriostatic water, sterile water for injection, or standard phosphate-buffered saline (PBS, pH 7.4).

When reconstituting high-concentration stock solutions (>2 mg/mL) in unbuffered water, the acidic nature of the peptide can temporarily lower the pH of the solution. If dissolution appears sluggish, adjusting the solution pH to neutrality (pH 7.0–7.4) using microscopic volumes of dilute sodium hydroxide (0.1 M NaOH) or utilizing PBS immediately restores full solubility.

Researchers calculating exact solvent volumes for target concentrations can utilize our interactive reconstitution calculator to minimize volumetric error during stock preparation.

Preclinical Applications and Mechanism of Action in Research

In vitro and animal model studies indicate that Thymosin Alpha-1 interacts with pattern recognition receptors, specifically Toll-like Receptor 4 (TLR4) and Toll-like Receptor 7 (TLR7), triggering intracellular signaling cascades via the MyD88 pathway. Preclinical evidence suggests that this signal transduction leads to the activation of nuclear factor kappa B (NF-κB) and subsequent transcription of specific cytokine profiles in isolated dendritic cells and macrophages.

Cell culture assays demonstrate that Thymosin Alpha-1 exposure modulates the maturation markers of early T-cell precursors, upregulating the expression of CD3, CD4, and CD8 surface markers in thymocyte populations. Furthermore, research models examining viral replication mechanisms utilize Thymosin Alpha-1 to observe changes in major histocompatibility complex (MHC) Class I expression on infected target cell lines.

Additional research explores the peptide's capacity to induce enzymatic activity of indoleamine 2,3-dioxygenase (IDO) in dendritic cells, pointing to a complex immunomodulatory role in balanced immune system models. All mechanisms detailed in literature reflect controlled preclinical or cell-based experiments aimed at elucidating basic signal transduction pathways.

Comparative Analysis: Thymosin Alpha-1 vs. Related Immunomodulatory Peptides

Within preclinical research literature, Thymosin Alpha-1 is frequently compared with other naturally derived or synthetic immunomodulatory compounds to contrast target receptor affinity, primary structural length, and functional mechanisms in vitro.

Compared to Thymosin Beta-4 (a 43-amino acid peptide focused primarily on actin-sequestering mechanisms and cell migration assays), Thymosin Alpha-1 exhibits a completely distinct primary sequence and secondary structure, acting primarily through TLR-mediated cytokine pathways rather than cytoskeletal regulation. When evaluated against antimicrobial host-defense peptides such as LL-37 or synthetic neuro-immunomodulators like Selank, Thymosin Alpha-1 shows lower direct lytic activity against bacterial membranes but a significantly higher capacity for specific T-cell receptor subunit upregulation in primary lymphoid cell cultures. Researchers interested in broader immunomodulatory compound classes can explore our comprehensive research hub.

PX1 Research Quality Control and Analytical Integrity

PX1 Research enforces stringent manufacturing and testing protocols for all research compounds supplied to academic, biotech, and institutional laboratories. Every production lot of Thymosin Alpha-1 undergoes synthesis in state-of-the-art GMP-compliant facilities located in the USA.

Analytical verification is performed by an independent ISO 17025 accredited testing laboratory. Each lot is subjected to reverse-phase HPLC (RP-HPLC) to confirm purity levels exceeding 98.0%, combined with ESI-MS mass spectrometry to confirm exact sequence molecular mass (3108.37 g/mol). Furthermore, endotoxin testing is performed via Chromogenic LAL assay to guarantee limits below <0.01 EU/mg, preventing confounding inflammatory responses in cell culture experiments.

All orders are fulfilled directly from our domestic distribution centers in California and Arizona, with same-day shipping offered Monday through Friday for fast laboratory deployment. Qualified institutional accounts can apply for high-volume supply arrangements via our wholesale portal.