TB-500 is the trade name most commonly used for a synthetic peptide corresponding to thymosin beta-4 (Tβ4). AminoOptimization Group supplies it as a lyophilised research powder in 5 mg and 10 mg presentations, tested to 99% purity by HPLC, with a Certificate of Analysis available for the lot supplied. This material is offered strictly for laboratory research use. It is not a drug, and it is not for human or veterinary use.
What is TB-500?
TB-500 corresponds in sequence to thymosin beta-4, a 43-amino-acid polypeptide belonging to the beta-thymosin family — a group of small, highly conserved, acidic peptides found across most vertebrate cell types. Tβ4 was first isolated from calf thymus tissue, which accounts for the “thymosin” designation, although later work established that it is expressed broadly and is not confined to thymic tissue or thymus-dependent biology.
The peptide’s principal characterized biochemical activity is the sequestration of monomeric, globular actin (G-actin). Tβ4 forms a 1:1 complex with G-actin, and published structural work attributes much of this binding activity to a short internal sequence — the heptapeptide motif LKKTETQ — that is conserved across the beta-thymosin family. This actin-binding function places Tβ4 among the intracellular regulators of cytoskeletal dynamics studied alongside profilin and other actin-monomer-binding proteins.
TB-500 is frequently confused with thymosin alpha-1, an unrelated 28-amino-acid peptide that was co-isolated from the same original thymic extract (“thymosin fraction 5”) during early fractionation work in the 1970s. The two compounds share a naming convention and a discovery history, not a structure or a mechanism: alpha-1 is studied in immunology contexts, while beta-4 is studied for its actin-related and cytoskeletal-signalling roles. Researchers ordering either compound should confirm the CAS number and sequence rather than relying on the commercial name alone.
Specifications
- Compound: TB-500 (Thymosin Beta-4, Tβ4)
- CAS number: 77591-33-4
- Molecular formula: C212H350N56O78S
- Molecular weight: 4963.55 g/mol
- Purity: 99% by HPLC
- Presentation: Lyophilised powder, sealed vial
- Available sizes: 5 mg, 10 mg
- Physical form: White to off-white powder
- Classification: Research peptide — not for human or veterinary use
Research context
Published research on thymosin beta-4 concentrates on its actin-binding activity and the downstream consequences of that activity in cultured cells. Because Tβ4 sequesters G-actin and alters the local pool of polymerization-competent actin, it appears in study designs investigating actin-dependent processes such as lamellipodial extension and cell migration in cultured cell lines.
A separate strand of literature examines Tβ4 and its fragments in endothelial cell culture assays and rodent injury models, where the peptide is treated as one variable among several affecting cell migration and vessel formation in vitro. Tβ4 is also examined for its interactions with other cytoskeletal regulators, including profilin and actin-capping proteins, as part of broader efforts to map the biochemistry of actin turnover.
None of this literature establishes safety or efficacy for use in humans or animals. It is provided as research context only.
Reconstitution
Lyophilised peptide requires reconstitution with a suitable sterile diluent before use in solution. Bacteriostatic water is the diluent most commonly specified for multi-use laboratory preparations; sterile water is typical for single-use work.
Direct the diluent stream against the inner wall of the vial rather than onto the powder itself, and allow the material to dissolve without agitation. Peptides are susceptible to shear stress — do not shake the vial. Swirl gently if needed, and expect full dissolution within a few minutes at room temperature.
Working concentration is a function of how much diluent is added to a given vial mass. Our peptide reconstitution calculator computes the resulting concentration for any combination of vial size and diluent volume.
Storage and stability
Before reconstitution: store the sealed vial in a freezer at -20 °C, protected from light. Lyophilised peptide is comparatively stable in this state. Brief excursions to ambient temperature during shipping are normal and are not expected to compromise a properly lyophilised product.
After reconstitution: refrigerate at 2–8 °C and protect from light. Reconstituted peptide in solution is materially less stable than the dry powder. Avoid repeated freeze-thaw cycles, which are a well-documented cause of aggregation and loss of measurable potency — aliquot instead if repeated sampling is required.
Inspect solutions before use. Cloudiness, visible particulate, or discolouration indicate the material should not be relied upon for quantitative work.
Certificate of Analysis
Every lot is tested by high-performance liquid chromatography, and the purity figure shown above refers to analytical results for the specific lot supplied — not to a generic specification. A Certificate of Analysis is available on request, and we will provide lot-specific documentation before purchase if your protocol requires it.
Purity by HPLC describes the proportion of the target peptide relative to detectable related substances. It is a statement about the material as manufactured and tested. It is expressly not a representation that the material is suitable for any use in humans or animals.
Handling and safety
Handle in accordance with good laboratory practice. Use appropriate personal protective equipment, work in a suitable containment environment, and dispose of material and consumables according to your institution’s requirements and applicable local regulation. Anyone with access to this material should understand that it is not for human or veterinary use.
Frequently asked questions
What is the difference between TB-500 and thymosin alpha-1?
The two are unrelated despite the shared “thymosin” name. Thymosin alpha-1 is a 28-amino-acid peptide studied in immunology contexts. TB-500 (thymosin beta-4) is a distinct 43-amino-acid peptide whose principal characterized activity is binding and sequestering monomeric actin. They differ in sequence, molecular weight, and the biology they are used to study.
Is TB-500 approved in Canada?
No. This compound has not been evaluated or authorised by Health Canada, the FDA, or any comparable regulatory authority. It carries no DIN or NPN, its safety and efficacy for human use have not been assessed, and it is supplied for laboratory research only.
How much diluent should be used?
That depends on the working concentration your protocol requires. Use the reconstitution calculator to work out the resulting concentration for your vial size.
How long is reconstituted material usable?
Stability in solution is shorter than in lyophilised form and depends on diluent, temperature, and handling. Refrigerate at 2–8 °C, protect from light, avoid freeze-thaw cycling, and validate stability for your own storage conditions if your work depends on it.
Do you provide a Certificate of Analysis?
Yes — lot-specific, available on request, including before purchase.
Research use only
This product is supplied solely for laboratory and scientific research. It is not a drug, food, cosmetic, or medical device, and it must not be administered to humans or animals. Nothing on this page is medical advice or a therapeutic claim. Full terms are set out in our Research Use Only Disclaimer.
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