Thymulin Molecular Weight, Sequence & CAS Reference

1. Chemical Identification and Molecular Classification

Thymulin (historically designated as Facteur Thymique Séreux or FTS) is a naturally occurring thymic nonapeptide hormone synthesized by thymic epithelial cells. In biological systems, it serves as a critical regulator of immune system regulation, T-cell differentiation, and thymic factor activity in cellular signaling pathways. As a synthetic research compound, pure Thymulin is studied in cell culture models and preclinical systems to decipher the precise mechanisms governing T-lymphocyte maturation and cytokine expression.

From a structural standpoint, native biological activity requires the stoichiometric coordination of a divalent zinc ion (Zn2+). In the absence of zinc, the nonapeptide exists in an inactive conformation. When researchers source high-purity thymulin 10mg for bench top investigation, understanding the structural composition of both the apo-peptide (zinc-free ligand) and the holo-peptide (zinc-bound complex) is essential for quantitative experimental design.

2. Primary Amino Acid Sequence and Structural Topology

The primary linear sequence of Thymulin consists of nine amino acid residues with a specific N-terminal modification. The published sequence, written from N-terminus to C-terminus, is:

Pyr-Ala-Lys-Ser-Gln-Gly-Gly-Ser-Asn-OH (or <Glu-Ala-Lys-Ser-Gln-Gly-Gly-Ser-Asn)

In standard single-letter amino acid notation, this sequence is represented as <EAKSQGGSN, where '<E' or 'Pyr' denotes a pyroglutamyl residue (5-oxoproline). This N-terminal cyclization occurs via the intramolecular condensation of glutamic acid, forming a lactam ring. This post-translational modification protects the N-terminus against rapid degradation by aminopeptidases in cell culture media, maintaining structural integrity during extended incubation periods.

The sequence features a balanced composition of polar, basic, and neutral residues. Lysine at position 3 provides a free epsilon-amino group, contributing a positive charge under physiological pH conditions. Asparagine at the C-terminus provides a free carboxylate group. Serine residues at positions 4 and 8 provide hydroxyl functional groups that participate in hydrogen bonding networks crucial for spatial stabilization upon ligand-receptor binding.

3. Molecular Weight, Formula, and CAS Registry Reference

Determining exact stoichiometry for mass spectrometry calibration requires precise empirical values for the uncoordinated peptide backbone. The structural specifications for apo-Thymulin (free base) are established as follows:

• CAS Registry Number: 63958-90-7 • Chemical Formula: C33H54N12O15 • Monoisotopic Mass: 858.3831 Da • Average Molecular Weight: 858.85 g/mol

When calculating concentrations for assays in analytical laboratory settings, researchers must distinguish between the apo-peptide formula weight (858.85 g/mol) and the zinc-coordinated complex. The addition of a single zinc ion (Zn2+, atomic mass ~65.38 g/mol) increases the nominal molecular weight of the functional zinc-thymulin complex to approximately 924.23 g/mol, excluding counterion mass. When evaluating batches across different catalog items within our research peptides catalog, verifying these chemical parameters ensures accurate equimolar preparations.

4. Coordination Chemistry: The Zinc-Thymulin Metallo-Complex

A critical property of Thymulin in preclinical literature is its absolute dependency on zinc for biological conformation and receptor binding affinity. Preclinical studies suggest that the zinc-free nonapeptide (apo-FTS) exhibits negligible affinity for T-cell receptors, whereas theequimolar equimolar coupling of Zn2+ induces a specific conformational change required for signaling transduction.

Spectroscopic analysis (including nuclear magnetic resonance and extended X-ray absorption fine structure spectroscopy) indicates that Zn2+ coordination involves specific functional groups within the nonapeptide backbone, notably the hydroxyl groups of Ser4 and Ser8, alongside the carboxyl functional group of the C-terminal Asn9. In laboratory environments where metal-free media or chelating agents (such as EDTA or EGTA) are utilized, researchers must account for potential zinc stripping, which converts active holo-thymulin into its inactive apo-form.

5. Salt Forms, Counterion Content, and Net Peptide Content

Synthetic peptides manufactured via solid-phase peptide synthesis (SPPS) are typically isolated following cleavage with trifluoroacetic acid (TFA). Consequently, the standard salt form of commercial synthesized Thymulin is Thymulin trifluoroacetate (TFA salt). Alternatively, for specialized cell line applications sensitive to TFA counterions, exchange to an acetate salt form may be executed.

Understanding net peptide content (NPC) is imperative for precise concentration calculations. The total mass of a lyophilized vial contains the pure peptide backbone, bound counterions (TFA or acetate), and residual trace moisture. For example, a peptide vial with an 80% net peptide content by weight contains 8.0 mg of active nonapeptide sequence per 10.0 mg of gross powder weight.

Researchers should always adjust their reconstitution calculations based on the lot-specific Net Peptide Content provided on the product certificate of analysis. Assuming 100% net peptide mass without counterion correction will result in systematic under-dosing in quantitative cellular assays. A detailed breakdown of counterion mass ratios is verified for every lot available through our analytical testing.

6. Comparative Structural Analysis Across Thymic Class Peptides

To contextualize Thymulin within immunopharmacology research, it is helpful to contrast its molecular features with other standard thymic and synthetic signaling peptides evaluated in preclinical models.

Thymulin is structurally distinct from larger thymic polypeptides such as Thymosin Alpha-1, a 28-amino-acid peptide (MW ~3,108.3 g/mol) derived from Prothymosin Alpha, and Thymosin Beta-4, a 43-amino-acid actin-sequestering peptide (MW ~4,963.5 g/mol). While Thymosin Alpha-1 primarily operates via Toll-like receptor signaling pathways, Thymulin acts through specific high-affinity surface receptors on T-lymphocytes that require zinc coordination. Furthermore, short regulatory sequences like Epithalon (a synthetic tetrapeptide, MW ~390.35 g/mol) operate through distinct genomic transcription pathways compared to the membrane-receptor binding mechanism of thymic nonapeptides.

Due to its compact size (9 amino acids vs 28+ residues), Thymulin presents a lower steric footprint, enabling specific spatial studies of peptide-metal interaction kinetics that are not feasible with larger protein fractions.

7. Reconstitution Procedures and In Vitro Laboratory Handling

Lyophilized Thymulin powder should be reconstituted using rigorous aseptic technique within a certified laminar flow hood. For in vitro cell culture and biochemical assays, sterile bacteriostatic water, sterile 0.9% sodium chloride, or phosphate-buffered saline (PBS, pH 7.4) may be utilized based on protocol specifications.

To ensure precise molarity when preparing stock solutions, researchers should utilize our interactive reconstitution calculator. This tool allows investigators to factor in solvent volume, vial mass, and lot-specific net peptide percentage to achieve exact micro-molar or nano-molar target concentrations.

Gentle swiveling of the vial is recommended to achieve complete dissolution. Rapid vortexing or excessive mechanical agitation should be avoided, as high shear stress can induce peptide aggregation or structural degradation. If zinc coordination assays are planned, ensure that reconstitution buffers are prepared using ultra-pure, trace-metal-grade water to prevent uncontrolled background ion complexation.

8. Quality Control, Analytical Validation, and COA Standards

Reliable preclinical investigation demands verified chemical purity and batch-to-batch consistency. PX1 Research enforces strict analytical standards for every lot of synthesized peptide. Standard quality assurance protocols include:

• High-Performance Liquid Chromatography (HPLC): Confirms chemical purity ≥98.0%, verifying the absence of incomplete truncation sequences or deletion peptides. • Matrix-Assisted Laser Desorption/Ionization (MALDI-TOF) or ESI Mass Spectrometry: Confirms exact mass identity against the theoretical 858.85 g/mol baseline. • Endotoxin Testing (LAL Assay): Verifies bacterial endotoxin levels remain strictly below regulatory thresholds (<0.01 EU/μg), preventing non-specific inflammatory signaling in cell assays.

Researchers can inspect comprehensive lot-specific documentation prior to purchase by reviewing our official COA hub. Every order ships directly from our US-based facilities with verifiable chromatographic data.

9. Preclinical Research Applications and Signaling Dynamics

In vitro and cellular model research focused on Thymulin examines its capacity to modulate immune signaling cascades. Preclinical studies suggest that the zinc-thymulin complex binds to specific high-affinity receptors on T-cells, triggering an intracellular signal transduction cascade that induces cyclic AMP (cAMP) accumulation.

Primary areas of preclinical investigation include:

1. T-Cell Differentiation: Evaluating the expression of differentiation markers (such as CD4, CD8, and Thy-1) on immature thymocytes following exposure to the peptide. 2. Cytokine Modulation: Measuring alterations in interleukin-2 (IL-2) production and receptor expression in lymphocyte cultures. 3. Neuroendocrine-Immune Interactions: Exploring how thymic factors interact with pituitary hormones in co-culture models to assess cross-system signaling.

Detailed research summaries and structural whitepapers regarding cellular signaling cascades are documented across our wider PX1 research library.

10. Storage Stability and Lab Logistics

Lyophilized Thymulin is stable at controlled room temperature during short-term transit, but long-term storage requires desiccation at -20°C to -80°C to prevent hydrolysis or oxidation of sensitive residues. Upon reconstitution, liquid aliquots should be divided into single-use working volumes to minimize freeze-thaw cycles, which degrade peptide integrity over time.

All products supplied by PX1 Research are manufactured in ISO 17025 accredited and GMP-compliant domestic facilities, ensuring strict analytical compliance. For institutional laboratories requiring large-scale allocations or batch reserve locks, detailed procurement options are accessible through our wholesale lab account portal.