TB-500

Description

RESEARCH USE ONLY: This product is intended for laboratory research purposes only. Not for human consumption.

Overview

TB-500 is a synthetic heptapeptide corresponding to amino acids 17–23 of thymosin beta-4 (Tβ4), with the N-acetylated sequence Ac-LKKTETQ (acetyl-Leu-Lys-Lys-Thr-Glu-Thr-Gln). This seven-residue actin-binding motif is the subject of preclinical research into cytoskeletal dynamics, directed cell migration, and angiogenesis-related signaling in controlled laboratory model systems.

Thymosin beta-4 is a naturally occurring 43-amino-acid polypeptide involved in actin regulation. TB-500 isolates the minimal active fragment of that sequence. This enables investigators to study cytoskeletal regulatory mechanisms independently of the full parent protein. It is a synthetic research analog. It is not a naturally derived extract and not a SARM.

TB-500 is not FDA-approved for human or veterinary therapeutic use. No Investigational New Drug (IND) application has been filed, and it has not undergone FDA-regulated clinical trials. It is supplied exclusively as a Research Use Only (RUO) compound for use by qualified researchers in controlled, non-clinical laboratory environments. It is not a dietary supplement.

Chemical and Molecular Properties

Property	Value
CAS Number	885340-08-9
Molecular Formula	C₃₈H₆₈N₁₀O₁₄
Molecular Weight	889.0 g/mol
IUPAC Name	L-Glutamine, N-acetyl-L-leucyl-L-lysyl-L-lysyl-L-threonyl-L-α-glutamyl-L-threonyl-
Synonyms	TB 500; TB-500; Ac-LKKTETQ
UNII	QHK6Z47GTG
PubChem CID	62707662
Typical Purity	≥99% (HPLC verified)
Physical Form	Lyophilized white to off-white powder
Solubility	Sterile water (primary); DMSO (application-specific)
Storage	−20°C, desiccated, protected from light and moisture
Classification	Research Use Only (RUO)

WADA Status: PROHIBITED. 

S0 (Non-Approved Substances) and S2 (Peptide Hormones, Growth Factors, Related Substances and Mimetics). Banned at all times, in- and out-of-competition. Non-Specified Substance. Researchers in sport science contexts must note this classification (2026 Prohibited List).

Mechanisms Investigated in Preclinical Research

Actin Sequestration and G-Actin/F-Actin Equilibrium

In cell-free and in vitro systems, TB-500 has been investigated for its role in monomeric G-actin binding. The Ac-LKKTETQ motif is thought to sequester globular actin monomers, influencing the dynamic equilibrium between G-actin and filamentous F-actin. This regulatory interaction is under examination as a molecular probe for cytoskeletal polymerization dynamics in eukaryotic cell models. [Sanders et al., 1992] 

Directed Cell Migration Pathways

Preclinical in vitro evidence suggests that the actin-binding region of TB-500 may be associated with cytoskeletal reorganization relevant to directed cell locomotion. Studies in model systems have investigated the relationship between LKKTETQ-mediated actin modulation and morphological transitions observed during cell migration experiments. Available data indicate that the Ac-LKKTETQ motif may influence cytoskeletal remodeling associated with directional movement in endothelial and epithelial cell culture frameworks. [Malinda et al., 1997] 

Angiogenesis-Related Signaling in Model Systems

Experimental data from thymosin beta-4 fragment studies indicate that the actin-binding region may be implicated in pathways influencing endothelial cytoskeletal behavior and vascular structure formation in laboratory assay systems. TB-500 is used in this context to evaluate mechanistic contributions to angiogenesis-related signaling independently of full-length Tβ4. [Philp et al., 2003] 

Research Applications

• G-actin sequestration assays and G-actin/F-actin polymerization balance studies in cell-free biochemical systems
• Cytoskeletal remodeling investigation in endothelial and epithelial cell culture models
• Directed cell migration mechanistic studies using the in vitro scratch assay and transwell migration frameworks
• Angiogenesis-related signaling pathway research in isolated endothelial model systems
• Structure–activity relationship (SAR) studies on thymosin beta-4 fragment derivatives and actin-binding motif variants
• Reference compound for competitive peptide-actin interaction characterization and analytical method development

Risk and Handling

Risk Tier: Low–Moderate (Synthetic Heptapeptide Research Compound)

TB-500 (Ac-LKKTETQ) is a synthetic peptide with no confirmed acute toxicity reported at research-relevant concentrations in preclinical systems. Risk arises primarily from improper handling, unvalidated reconstitution procedures, or use outside a controlled laboratory environment.

Handling Precautions

TB-500 must be handled exclusively by qualified researchers in a controlled, non-clinical laboratory environment. Standard PPE (including nitrile gloves, safety glasses, and a lab coat) is required during all handling and reconstitution procedures. Avoid inhalation of lyophilized powder during weighing or transfer. Researchers should consult the Safety Data Sheet (SDS) before first use and follow all applicable institutional safety protocols.  

Exposure Risks

No confirmed occupational exposure hazard data are established for TB-500 at research concentrations. As a biologically active peptide fragment, systemic exposure outside controlled experimental conditions is inadvisable. Avoid inhalation of reconstituted aerosols. In the event of accidental skin or eye contact, flush thoroughly with water and consult institutional safety protocols. No human safety data has been established. Comprehensive toxicological profiling of TB-500 in humans is absent from the peer-reviewed literature. All available data derive exclusively from in vitro and preclinical animal model studies. Long-term toxicity data are not established.  

Storage

• Lyophilized powder: −20°C, desiccated, protected from light and moisture. Stable ≥24 months under correct storage conditions.
• Reconstituted solution: 2–8°C. Use within 4 weeks of reconstitution.
• Avoid repeated freeze-thaw cycles (aliquot before freezing to preserve peptide integrity). 
• Soluble in sterile water for primary research applications. May be dissolved in DMSO for specific experimental protocols. 

Regulatory Status

TB-500 is not approved by the FDA for human or veterinary therapeutic use. It is classified as a Research Use Only (RUO) compound. It is not a lawful dietary supplement ingredient under 21 CFR and may not be marketed or sold for human consumption in the United States.

Why Buy TB-500 from PureRawz

Each batch of TB-500 supplied by PureRawz is independently tested by accredited third-party laboratories before release. A batch-specific Certificate of Analysis (COA) is available for researcher verification before experimental use, confirming both compound identity and purity against established reference standards. Molecular formula and weight are cross-referenced against CAS 885340-08-9 and PubChem CID 62707662 to ensure lot-to-lot consistency.

Quality Assurance at PureRawz

• Compound identity confirmed by HPLC and mass spectrometry (MS) against CAS 885340-08-9
• Purity verified at ≥99% by HPLC per production batch
• Molecular identity cross-referenced against PubChem CID 62707662
• Moisture content is tested per batch before dispatch
• Microbial contamination screening performed on all peptide production batches
• Heavy metals screening (Pb, Cd, As, Hg) conducted per USP standards, where applicable
• Batch-specific lot number assigned; full traceability maintained from synthesis to dispatch
• Certificate of Analysis (COA) available per lot (independently generated by an accredited third-party laboratory)
• Safety Data Sheet (SDS) available on request

PureRawz does not self-certify. All quality verification is conducted by accredited independent laboratories

References

1. Sanders MC, Goldstein AL, Wang YL. Thymosin beta 4 (Fx peptide) is a potent regulator of actin polymerization in living cells. Proceedings of the National Academy of Sciences. 1992;89(10):4678–4682. https://pubmed.ncbi.nlm.nih.gov/1584799/ 
2. Malinda KM, Goldstein AL, Kleinman HK. Thymosin beta 4 stimulates directional migration of human umbilical vein endothelial cells. FASEB Journal. 1997;11(6):474–481. https://pubmed.ncbi.nlm.nih.gov/9194525/
3. Philp D, Huff T, Gho YS, Hannappel E, Kleinman HK. The actin-binding site on thymosin beta4 promotes angiogenesis. FASEB Journal. 2003;17(14):2103–2105. https://pubmed.ncbi.nlm.nih.gov/14500546/ 

FAQs

What is the actin-binding motif LKKTETQ? 

LKKTETQ (Leu-Lys-Lys-Thr-Glu-Thr-Gln) is the specific seven-amino-acid sequence at positions 17–23 of thymosin beta-4, representing the minimal active region implicated in G-actin sequestration in preclinical research. In TB-500, this sequence is N-acetylated at the leucine terminus (Ac-LKKTETQ), which confers proteolytic stability relevant to in vitro laboratory applications. 

What signaling mechanisms does TB-500 engage in preclinical models? 

In preclinical and in vitro research systems, TB-500 is studied for its role in actin monomer sequestration. It specifically binds G-actin to modulate the G-actin/F-actin polymerization equilibrium. Downstream effects under investigation include cytoskeletal reorganization associated with directed cell migration and endothelial signaling pathways relevant to angiogenesis model research. 

Is TB-500 FDA-approved for human use? 

No. TB-500 is not FDA-approved for human or veterinary therapeutic use. No Investigational New Drug (IND) application has been filed for TB-500, and it has not undergone FDA-regulated clinical trials. It is supplied exclusively as a Research Use Only (RUO) compound for use by qualified researchers in controlled, non-clinical laboratory environments. It is not a dietary supplement and may not be lawfully sold for human consumption under 21 CFR.

What research applications involve TB-500? 

TB-500 is used in preclinical research to investigate actin-mediated cytoskeletal dynamics, directed cell migration pathway mechanisms, and angiogenesis-related signaling in endothelial model systems. It is relevant to in vitro studies evaluating G-actin/F-actin balance, cytoskeletal remodeling, and vascular network formation in controlled laboratory assay frameworks. All applications are restricted to non-clinical research use only.

What is TB-500, and how does it differ from thymosin beta-4? 

TB-500 (Ac-LKKTETQ) is a synthetic heptapeptide corresponding to amino acids 17–23 of thymosin beta-4 (Tβ4), a naturally occurring 43-amino-acid polypeptide. Unlike full-length Tβ4, TB-500 isolates the conserved actin-binding motif, enabling researchers to study cytoskeletal dynamics and cell migration mechanisms independently of the full parent protein in controlled preclinical laboratory systems. It is a synthetic research compound, not a naturally derived extract. [Sanders et al., 1992]

Is TB-500 prohibited by WADA? 

Yes. TB-500 is explicitly prohibited under WADA 2026 Prohibited List Section S0 (Non-Approved Substances) and Section S2 (Peptide Hormones, Growth Factors, Related Substances and Mimetics). It is classified as a Non-Specified Substance and is banned at all times, carrying maximum anti-doping sanctions. Researchers in sport science or athletic performance contexts must independently verify all applicable compliance obligations before use.

How should TB-500 be stored to maintain research integrity? 

Lyophilized TB-500 should be stored at −20°C in dry, light-protected, desiccated conditions. Following reconstitution in sterile water or DMSO, the material should be maintained at 2–8°C and used within four weeks. Repeated freeze-thaw cycles degrade peptide integrity and may compromise experimental results; pre-aliquoting before freezing is standard recommended practice.

Disclaimer: Preclinical and published scientific research indicate potential mechanisms of action for this compound in laboratory and animal models. Any references to published studies are for informational purposes only and do not constitute a claim that this product produces the same effects in humans. The safety and efficacy of this compound in humans have not been established.

ATTENTION: All products sold by PureRawz are intended for laboratory and research purposes only and are not approved for human consumption, veterinary use, or any other use. Products are not evaluated by the FDA and are not intended to diagnose, treat, cure, or prevent any disease. Customers assume full responsibility for the lawful use of these products in accordance with all applicable federal, state, and local regulations.