Immunology research
Work on T-cell maturation and dendritic-cell function, where the acetylated N-terminus matters because it is the form used in the published literature.
Peptide · Thymic
Thymosin α1 (Thymalfasin)
The acetylated 28-residue thymic peptide, released against a full pharmacopoeial-style panel rather than a single purity figure. This is the product where the certificate is the argument.
Also known as Thymosin α1 · thymalfasin · Tα1 · thymosin alpha-1
Sequence · 28 residues
AcidicBasicHydrophobicPolar
- Residues
- 28
- Molecular weight
- 3108.28
- Formula
- C129H215N33O55
- Purity
- 99.5% assay
Identity data as printed on the batch certificate of analysis.
Overview
What Thymosin α1 is
Thymosin α1 is a 28-residue peptide, acetylated on the N-terminal serine and free at the C-terminal asparagine. The acetylation is not cosmetic: it changes the mass by 42 Da, it is part of what the molecule is, and a supplier who cannot state the N-terminal modification cannot tell you which peptide they are shipping.
Most certificates for this product report purity and stop. The tests that actually discriminate sit further down the panel — specific optical rotation, amino acid composition, high-molecular-weight protein, and the residual acid content that tells you whether the peptide is free or in salt form.
The batch we hold is a 24-item report at that depth: rotation −106.6°, pH 5.3, water 2.4%, acetic acid not detected, TFA 0.003%, largest single impurity 0.48%, total impurities 0.63%, and an assay of 99.5%. Free peptide, released against an in-house standard.
- 24-item release panel including specific rotation and amino acid composition
- Assayed 99.5% on batch TA2606261; total impurities 0.63%, largest single 0.48%
- Free peptide — acetic acid not detected, trifluoroacetate 0.003%
- High-molecular-weight protein 0.09%, well inside the ≤1.0% limit
Identity
The record.
The identifiers your specification sheet, customs paperwork and product label all have to agree on. Where a number depends on the salt form, both are given.
- Chemical name
- N-acetyl-L-seryl-…-L-asparagine, 28 residues
- Common name
- Thymosin α1; thymalfasin; Tα1
- CAS number
- 62304-98-7
- Molecular formula
- C₁₂₉H₂₁₅N₃₃O₅₅
- Molecular weight
- 3108.28 g/mol
- Residue count
- 28 (N-acetylated, C-terminal free acid)
- Appearance
- White powder
- Solubility
- Soluble in trifluoroacetic acid; slightly soluble in water
- pH (1% solution)
- 4.5 – 6.0
- Specific rotation [α]²⁰D
- −100.0° to −110.0°
- Water content
- ≤ 5.0% (Karl Fischer)
- Counter-ion
- None — free peptide
- Storage
- 2–8 °C, airtight, protected from light
HS codes are indicative only. Final classification is confirmed per shipment with your customs broker.
Manufacture
How it is made.
A 28-mer with a defined N-terminus. The acetylation and the purification are the two steps that decide whether the certificate can support the structure.
- 01
Solid-phase assembly
The 28-residue chain is built on resin and the N-terminus acetylated on-resin, so the modification is part of the synthesis rather than a later reaction that may go to completion unevenly.
- 02
Cleavage and deprotection
Acid cleavage releases the peptide and removes side-chain protecting groups; the C-terminus is left as the free acid, matching the pharmacopoeial substance.
- 03
Preparative purification
Reversed-phase HPLC removes truncated and acetylated-by-product sequences. The largest single impurity figure on the certificate is the direct measure of how well this step went.
- 04
Drying and release
Lyophilised to a defined water content, then released against the 24-item panel — rotation, amino acid composition, residual solvents and HMW protein included.
Applications
Where it is used.
Supplied to laboratories working on T-cell biology and immune-response research. We supply the peptide and the documentation; the study design is the researcher's.
Assay development
Used as a reference or calibrant, which is where an amino acid composition result and a rotation value earn their place — a standard with the wrong sequence is worse than no standard.
Formulation studies
Free peptide with low residual acid, for groups studying solution behaviour without the confound of a counter-ion.
Specification
Release criteria.
The written limits we release against, with the method used to test each one. Batch results for the lot you receive are stated on its certificate of analysis.
| Parameter | Limit | Method |
|---|---|---|
| Appearance | White or almost white powder | Visual |
| Solubility | Soluble in TFA; slightly soluble in water | Visual |
| Specific optical rotation | −100.0° to −110.0° | Polarimetry |
| Identification | Retention time matches reference | HPLC |
| Molecular ion mass | 3108.28 ± 2 | MS |
| Clarity and colour of solution | Clear and colourless | Visual |
| pH | 4.5 – 6.0 | Potentiometric |
| Water content | ≤ 5.0% | Karl Fischer |
| Acetic acid | ≤ 0.5% | HPLC |
| Trifluoroacetate | ≤ 0.25% | HPLC |
| Methanol | ≤ 0.3% | GC |
| Acetonitrile | ≤ 0.041% | GC |
| DMF | ≤ 0.088% | GC |
| Amino acid composition | Within range for 8 residues | Amino acid analysis |
| Largest individual impurity | ≤ 0.5% | HPLC |
| Total impurities | ≤ 2.0% | HPLC |
| High-molecular-weight protein | ≤ 1.0% | HPLC |
| Bacterial endotoxin | ≤ 10 EU/mg | LAL |
| TAMC / TYMC | ≤ 100 cfu/g each | Plate count |
| Escherichia coli | Not detected | Plate count |
| Assay | 95.0 – 105.0% | In-house |
Tighter limits — for example a lower heavy-metal ceiling or a residual-solvent panel — can be quoted against your own specification wording.
HPLC · ES019
Certificate
Reading the certificate.
This is one of two products in our range where the certificate runs to a full pharmacopoeial-style panel. Here is what to look at, in order.
Specific rotation is the identity test most suppliers skip
Rotation measures chirality, not concentration. A peptide assembled with racemised residues can pass an HPLC purity test and still rotate outside −100° to −110°. If the number is missing, the identity claim rests on retention time alone.
Amino acid composition catches the wrong sequence
Hydrolysis and analysis of the individual residues confirms that the chain is what the sequence says it is. Eight residues are checked here; a truncated or substituted analogue will not match the expected ratios.
Residual acid tells you the form
Acetic acid not detected and TFA at 0.003% means this is the free peptide, not an acetate or trifluoroacetate salt. That matters because the salt and the free base have different masses and different behaviour in solution — and the page would be wrong if it claimed a salt form the certificate contradicts.
Documentation & packaging
What ships with it.
The paperwork travels with the goods. If your QA team needs an extra declaration, ask before the order is released — some are issued per production lot and cannot be retrofitted.
Certificate of analysis
The 24-item panel: rotation, amino acid composition, residual solvents, HMW protein, microbiological results and assay.
Analytical data
HPLC chromatogram at 220 nm (Kromasil 300-5-C18, 12→30% over 45 min) and the mass spectrum confirming 3108.28.
SDS & specification
Safety data sheet and the in-house standard the batch was released against.
Batch traceability
Manufacture date, retest date and lot number on every certificate; the file travels with the shipment.
| Pack size | Presentation | Typical use |
|---|---|---|
| 1–10 g | Amber vial, 10 mL | Evaluation |
| 25–50 g | Amber vial, 50 mL | Pilot scale |
| 100 g | Amber vial, 100 mL | Small commercial |
| 1 kg+ | Foil bag, quoted per order | Bulk |
Questions
Before you order.
The questions buyers actually ask about Thymosin α1. Anything not covered here, ask directly — you will get an answer from someone technical, not a template.
Is the peptide acetylated?
Yes. The N-terminus is acetylated and the C-terminus is the free acid, which is the form described in the literature and the form the molecular weight of 3108.28 corresponds to. The unacetylated sequence would be 42 Da lighter.
Is it supplied as an acetate salt?
No. Acetic acid is not detected and trifluoroacetate is 0.003%, so the batch is the free peptide. If your protocol specifies a salt form, say so before ordering — this is not something to assume from a catalogue listing.
Why does the certificate list so many tests?
Because for this molecule the purity figure alone does not establish identity. Rotation, amino acid composition and molecular-ion mass each test a different property, and a 28-mer has enough ways to be subtly wrong that one number is thin evidence.
What is the difference between ES019 and ES019-1?
ES019 is this product. ES019-1 is a separate catalogue entry for the salt-free specification, and documentation for one does not transfer to the other. If your specification references a particular form, quote the code on the purchase order.
How should it be stored?
2–8 °C, airtight, protected from light. Not frozen: the certificate and the SDS both specify refrigerated storage, and freezing a lyophilised cake that was dried to 2.4% water gains nothing and adds handling risk.
Can you supply a larger lot with the same panel?
Yes, quoted per order. The release panel stays the same regardless of quantity — what changes is the lead time, not the testing.
Related
Often quoted together.
Quotation
Ask for Thymosin α1, by the gram.
Send the quantity, the grade you need and the destination. You will get a written quotation with lead time, packaging options and the documentation set for this material.