Description
PrymaLab · Research Use Only
TB-500 Nasal Spray
Thymosin beta-4 · 43 residues · CAS 77591-33-4
TB-500 nasal spray supplies thymosin beta-4, CAS 77591-33-4, molecular formula C212H350N56O78S, molecular weight 4963.44. Despite the code name suggesting a fragment, material sold as TB-500 is generally the complete 43-residue sequence.
Specification Table
| Property | Value |
|---|---|
| Compound | Thymosin beta-4 |
| Common designation | TB-500 |
| CAS number | 77591-33-4 |
| Molecular formula | C212H350N56O78S |
| Molecular weight | 4963.44 g/mol |
| Residue count | 43 |
| N-terminus | Acetylated |
| Principal molecular interaction | Sequesters monomeric G-actin |
| Actin-binding motif | LKKTET, residues 17 to 22 |
| Structural class | Intrinsically disordered in free solution |
| Abundance | Among the most abundant proteins in many mammalian cell types |
| Related but distinct compound | Ac-SDKP, the N-terminal tetrapeptide, carries its own separate activity and is sold separately |
| Enzyme liberating Ac-SDKP | Prolyl oligopeptidase |
| Oxidation-prone residues | One methionine |
| Cysteine content | None. No disulfide chemistry |
| Format | Metered nasal spray, solution state |
| Purity | Per lot-specific certificate of analysis |
| Storage | 2-8°C, protected from light. Do not freeze |
| Regulatory status | No approved human or veterinary formulation in any jurisdiction |
What Is TB-500, Exactly?
The TB-500 nasal spray name creates a persistent confusion that is worth clearing up before anything else, because two different substances circulate under overlapping descriptions.
Thymosin beta-4 is a 43-residue protein, acetylated at the amino terminus, and among the most abundant proteins in many mammalian cell types. Material sold as TB-500 is generally this complete sequence.
Ac-SDKP is the amino-terminal tetrapeptide of that protein, liberated by prolyl oligopeptidase, and it has been characterised independently and carries its own reported activities, which are not the same as those of the parent.
Descriptions of TB-500 as a fragment of thymosin beta-4 conflate the two. This catalogue sells them as separate products for that reason, and a certificate stating a mass near 4963 confirms the full protein while a mass near 488 confirms the tetrapeptide.
The practical consequence is that literature about Ac-SDKP does not transfer to TB-500 and vice versa. Checking which molecule a paper actually used is a necessary step before citing it.
What Does Thymosin Beta-4 Do Molecularly?
The core biochemistry is well established and considerably simpler than the marketing around the compound suggests.
Thymosin beta-4 binds monomeric G-actin and holds it in a sequestered pool, keeping it from adding to growing filaments, and it is the principal actin-sequestering protein in many cell types, and its abundance reflects that structural role.
The interaction runs through the LKKTET motif at residues 17 to 22, a short sequence that is conserved across the beta-thymosin family and that constitutes the functional core.
In free solution the protein is intrinsically disordered, adopting structure only on binding. That property is common among regulatory proteins and it complicates structural work, since there is no single conformation to solve.
Actin sequestration is a cytoskeletal function, and cytoskeletal dynamics underlie migration, division and shape change in essentially every cell type. That breadth is why the compound is associated with such a wide range of reported effects, and also why attributing any specific one to it is difficult.
Does TB500 Nasal Spray Work, and at What Dosage?
Both halves of that question deserve direct answers, and both answers are qualified.
Published rodent work has used amounts spanning roughly 0.5 to 20 mg/kg depending on model and route, with a substantial share of studies clustering in the low milligrams per kilogram. Those figures come predominantly from intraperitoneal and intravenous exposure.
Intranasal work specifically is thin, and extrapolating a published intraperitoneal figure to a nasal spray is an assumption about bioavailability, and for a 4963-dalton protein that assumption is a large one.
Size is the constraint. Intranasal bioavailability falls sharply with molecular weight, and published figures for proteins in this range are generally low single-digit percentages at best. A peptide of 800 daltons and a protein of 4963 daltons do not behave alike through mucosa.
No receptor has been identified. Actin sequestration is a direct protein-protein interaction rather than receptor signalling, which means the usual pharmacological tools for establishing mechanism do not apply.
Human clinical evidence is limited, with no completed large randomised trial published for the indications the compound is associated with.
How Does the Spray Compare With Injection for a 4963-Dalton Protein?
For a TB-500 nasal spray the route comparison is less balanced than for the small peptides in this range, and molecular weight is why.
Injection delivers a known quantity, and for a protein of this size that certainty is worth more than usual, because the alternative is a delivery route whose efficiency is both low and variable.
The nasal epithelium presents a tight barrier to molecules above roughly one kilodalton. Thymosin beta-4 is five times that. The fraction crossing intact is small, and the fraction reaching the central nervous system through olfactory transport is smaller still.
Against that, the protein is intrinsically disordered rather than folded, so it has no tertiary structure to lose at an air-liquid interface. That makes it more tolerant of the spray format than a folded protein of similar mass would be.
The honest framing is that this format suits questions about intranasal delivery of a large peptide, and suits questions about actin sequestration considerably less well than a measured injection would.
How Does an Intrinsically Disordered Protein Behave in Solution?
Most proteins in a spray raise folding concerns. This one raises different ones, and the difference is worth understanding.
A folded protein holds a defined tertiary structure stabilised by a hydrophobic core. Denaturation exposes that core, the exposed surfaces associate, and aggregation follows. Air-liquid interfaces drive that process efficiently.
An intrinsically disordered protein has no such core to expose. It samples an ensemble of extended conformations continuously, so there is no folded state to lose and no classical denaturation to guard against.
That does not make it aggregation-proof. Disordered chains associate through transient contacts and can form aggregates by a different route, and at 43 residues there is ample chain length for it.
The practical difference is that gentle handling matters less here than for a folded protein of similar mass, while concentration and time matter more. Aggregation in disordered systems is strongly concentration-dependent.
It also means a clarity check is less informative than usual, because disordered-protein aggregates can remain soluble and invisible. Size-exclusion chromatography is the check that actually sees them.
What Should a TB-500 Nasal Spray Certificate Show?
A 43-residue protein needs more analytical attention than a short peptide, and the failure modes differ.
Mass confirmation against 4963.44. At this length, deletion sequences differing by one residue sit within a fraction of a percent of the target mass and require high-resolution instrumentation to resolve rather than a bench instrument.
Purity by size-exclusion chromatography in addition to reversed-phase. Size-exclusion detects soluble aggregate, which reversed-phase can miss entirely and which matters for a protein of this size in solution.
Confirmation of the amino-terminal acetylation. An unacetylated preparation weighs 42 daltons less and has a free amine at the terminus, which changes both charge and aminopeptidase susceptibility.
A statement on the oxidised fraction at the single methionine, quantified rather than merely absent from the report.
For a TB-500 nasal spray specifically, add analytically determined solution concentration and the fill date, since both are properties of the finished product rather than of the peptide.
How Should the Spray Be Handled?
A TB-500 nasal spray wants refrigeration, darkness, no freezing and gentle handling.
Hold at 2 to 8 degrees Celsius. The single methionine is the only oxidation-sensitive residue, and with no cysteine there is no disulfide chemistry to manage, which makes this protein more forgiving in solution than its size suggests.
Avoid agitation despite the disordered structure. Aggregation in disordered proteins proceeds by a different route than in folded ones, but it still proceeds, and a 43-residue chain has ample surface for intermolecular association.
Do not freeze the device, since the pump assembly is the constraint rather than the protein itself.
Inspect for clarity before each use. Cloudiness indicates aggregation, and aggregated material is not recoverable.
Confirm the mass on the certificate reads near 4963 rather than near 488, which is the one check that distinguishes this product from its tetrapeptide relative.
A final note on the literature. Much of the promotional material around this compound cites work on Ac-SDKP, on thymosin beta-4 in wound models, and on the intact protein in cardiac studies interchangeably.
Those are three separate bodies of work using two different molecules across several model systems. Reading a citation back to its methods section before relying on it is the only way to know which one a claim actually rests on.
For a compound this widely marketed, that check separates the defensible statements from the inherited ones faster than any other habit.
The same caution applies to molecular weight. A figure near 4963 and a figure near 488 describe two different products, and secondary sources move between them without flagging the switch.
Confirming which one a supplier means before ordering avoids the most expensive mistake available with this compound.
A last practical note on concentration. Because aggregation in a disordered protein is strongly concentration-dependent, the working concentration is itself a stability variable rather than only an experimental one.
A stock held at high concentration for convenience will aggregate faster than the same material held dilute, which inverts the usual instinct to concentrate for storage.
Where a programme spans months, holding several dilute aliquots beats holding one concentrated stock.
That is the opposite of what most peptide storage guidance implies, and it is a direct consequence of the disordered architecture described above.
Published Literature
References verified against the publisher record. Thymosin beta-4 has a substantial independent biochemistry literature, distinct from the promotional material surrounding the TB-500 designation.
- Safer D, Elzinga M, Nachmias VT. Journal of Biological Chemistry. 1991;266(7):4029-4032.
- Goldstein AL, Hannappel E, Kleinman HK. Trends in Molecular Medicine. 2005;11(9):421-429.
- Xu TJ, Wang Q, Ma XW, Zhang Z, Zhang W, Xue XC, Zhang C, Hao Q, Li WN, Zhang YQ, Li M. Expert Opinion on Biological Therapy. 2020;20(7):723-735.
- Cavasin MA, Rhaleb NE, Yang XP, Carretero OA. Hypertension. 2004;43(6):1140-1145.
- Hannappel E. Annals of the New York Academy of Sciences. 2007;1112:21-37.
- Illum L. Journal of Pharmacy and Pharmacology. 2004;56(1):3-17.
- Lochhead JJ, Thorne RG. Advanced Drug Delivery Reviews. 2012;64(7):614-628.
Frequently Asked Questions
What is TB-500 nasal spray?
A metered spray supplying thymosin beta-4, CAS 77591-33-4, the complete 43-residue acetylated protein at 4963.44 daltons. Despite the code name suggesting a fragment, TB-500 material is generally the full sequence. Laboratory research use only.
Is TB-500 the same as Ac-SDKP?
No, and this is the most common confusion around the compound. Ac-SDKP is the amino-terminal tetrapeptide liberated by prolyl oligopeptidase, characterised independently with its own reported activities. They are sold separately here for that reason.
How can the two be told apart?
By mass. A certificate reading near 4963 confirms the full protein. A certificate reading near 488 confirms the tetrapeptide. Literature about one does not transfer to the other.
What does thymosin beta-4 do molecularly?
It binds monomeric G-actin and holds it in a sequestered pool, preventing addition to growing filaments. It is the principal actin-sequestering protein in many cell types, which is why it is so abundant.
Which part of the sequence does the binding?
The LKKTET motif at residues 17 to 22, a short sequence conserved across the beta-thymosin family. That motif constitutes the functional core of the protein.
Why is structural work on it difficult?
Because it is intrinsically disordered in free solution, adopting structure only on binding. There is no single conformation to solve, which is common among regulatory proteins and inconvenient for crystallography.
What dosage appears in published work?
Rodent studies span roughly 0.5 to 20 mg/kg depending on model and route, with many clustering in the low milligrams per kilogram. Those figures come predominantly from intraperitoneal and intravenous exposure rather than intranasal.
Does that transfer to a nasal spray?
Not reliably. Intranasal bioavailability falls sharply with molecular weight, and at 4963 daltons this protein is five times the size at which the nasal epithelium starts presenting a serious barrier.
Has a receptor been identified?
No. Actin sequestration is a direct protein-protein interaction rather than receptor signalling, so the usual pharmacological tools for establishing mechanism, such as selective antagonists, do not apply here.
Is the spray format suitable despite the size?
Partly. The protein is intrinsically disordered rather than folded, so it has no tertiary structure to lose at an air-liquid interface, which makes it more tolerant of the format than a folded protein of similar mass.
What is the key certificate check?
That the stated mass reads near 4963 rather than near 488. That single number distinguishes this product from its tetrapeptide relative, and it is the check most worth making before anything else.
Compliance Statement
TB-500 nasal spray is sold exclusively for laboratory research use. It is not a drug, food, or cosmetic product, and it is not a dietary product of any kind. It is not approved by the FDA or any comparable authority for human or veterinary use, no receptor for this protein has been identified, human clinical evidence is limited, and amounts cited are figures from published rodent studies. This product is not intended to diagnose, treat, cure, or prevent any disease. It must not be given to humans or animals. Purchase is restricted to qualified researchers and institutions operating within applicable laws. All handling is the responsibility of the purchasing laboratory.
Other formats of TB-500
TB-500 is also stocked as TB-500 5mg/ml preloaded 3ml pen, TB-500 (Thymosin Beta-4) 5mg, BPC-157 + TB500 (10mg/10mg) "Wolverine Blend", BPC-157 5MG, BPC-157 10MG, BPC-157 Capsules (60/500mcg) and BPC 157 5mg + TB500 5mg. Each listing states its own quantity and concentration, and the pen and vial comparison explains what changes between formats.
19 reviews for TB-500 Peptide Nasal Spray