TB-500 (Thymosin Beta-4 Fragment 17–23)
Identification
| Property |
Value |
| Full Name |
Thymosin Beta-4 fragment (17–23), synthetic |
| Sequence |
Leu-Lys-Lys-Thr-Glu-Thr-Gln (LKKTETQ) |
| Source |
Synthetic analog of the actin-binding domain (residues 17–23) of Thymosin Beta-4 |
| Molecular Formula |
C₃₈H₆₈N₁₀O₁₄ |
| Molecular Weight |
~889 Da |
| Amino Acid Count |
7 |
| Appearance |
White to off-white lyophilized powder |
| Solubility |
Freely soluble in water and aqueous buffers |
Biological Context
Thymosin Beta-4 (Tβ4) is a 43-amino acid polypeptide (MW ~4,921 Da) present in most mammalian tissues. It was originally identified as a thymic hormone but is now recognized as the principal G-actin sequestering peptide in eukaryotic cells. The synthetic fragment TB-500 corresponds to the N-terminal actin-binding domain of Tβ4 (residues 17–23, LKKTETQ), which is essential for its actin-polymerization regulatory functions.
The fragment notation "17–23" refers to the amino acid positions within the full Tβ4 sequence, not molecular weight or any other parameter.
Research Applications
| Research Domain |
Description |
| Cell Migration |
Promotes directional cell migration (chemotaxis) in fibroblasts, keratinocytes, and endothelial cells; key mediator of wound re-epithelialization |
| Angiogenesis |
Stimulates endothelial cell differentiation into capillary-like structures; upregulates VEGF and matrix metalloproteinase expression |
| Wound Healing |
Accelerates full-thickness dermal wound closure; increases collagen deposition and wound tensile strength |
| Actin Polymerization |
Binds G-actin monomers (Kd ~0.7 μM) and regulates the G-actin/F-actin equilibrium; facilitates localized actin filament assembly at the leading edge of migrating cells |
| Anti-inflammatory Activity |
Suppresses neutrophil infiltration and inflammatory cytokine release at injury sites |
| Cardiac Protection |
Preclinical models of myocardial infarction show reduced scar size and improved ejection fraction |
| Hair Follicle Cycling |
Promotes anagen phase induction and prolongs active growth phase in hair follicle models |
Mechanisms of Action
| Mechanism |
Description |
| Actin Sequestration |
The LKKTETQ motif binds ATP-G-actin monomers with high affinity, maintaining a pool of polymerization-competent actin for rapid filament assembly |
| Chemotactic Signaling |
TB-500 acts as a chemoattractant for endothelial cells, fibroblasts, and keratinocytes, guiding migration toward injury sites |
| Pro-angiogenic Gene Expression |
Upregulates VEGF, bFGF, and MMP-2 expression through PI3K/Akt and NF-κB signaling cascades |
| Anti-apoptotic Effects |
Reduces caspase-3 activation and increases Bcl-2/Bax ratio in cells subjected to oxidative stress |
Quality Specifications
| Parameter |
Specification |
Method |
| Purity (HPLC) |
≥99.0% |
RP-HPLC, C18 column, 214 nm |
| Mass Identity |
MW ±1.0 Da |
ESI-MS |
| Water Content |
≤5.0% |
Karl Fischer titration |
| Peptide Content |
≥80.0% |
Amino acid analysis |
| Acetate/TFA Content |
≤1.0% (acetate salt) |
Ion chromatography |
| Endotoxin |
≤1.0 EU/mg |
LAL kinetic chromogenic |
| Residual Solvents |
≤ ICH Q3C limits |
Headspace GC |
| pH (1 mg/mL) |
5.0–7.5 |
Potentiometric |
Available Configurations
| Format |
Size |
Vials per Kit |
| Standard Research Kit |
5 mg × 10 vials |
10 |
| Extended Research Kit |
10 mg × 10 vials |
10 |
| Custom Configuration |
Bulk/custom |
Per project |
Storage & Stability
| Condition |
Requirement |
| Short-term Storage |
2–8°C, lyophilized form |
| Long-term Storage |
−20°C to −80°C, desiccated |
| Reconstituted |
24 h at 2–8°C; aliquot and freeze at −20°C for extended storage |
| Light Sensitivity |
Protect from light |
| Shipping |
Ambient temperature acceptable for ≤14 days during transit |
Documentation
- COA per batch: HPLC chromatogram, MS spectrum, quantitative purity
- MSDS supplied with each shipment
Special Notes
- FOR LABORATORY RESEARCH USE ONLY.
- TB-500 is a synthetic fragment and is not isolated from biological sources. The product does not contain thymic tissue extracts or any biologically derived raw materials.
- The G-actin binding affinity of the LKKTETQ fragment is retained at non-physiological pH (5.5–8.5 range), but experimental protocols should consider buffer conditions for optimal activity.
- As a short linear peptide, TB-500 is susceptible to non-specific adsorption to plastic labware. Use siliconized or low-retention vials and pipette tips for dilute solutions.
Key Research References
| Reference |
PMID |
Key Finding |
| Malinda KM et al. "Thymosin β4 accelerates wound healing." J Invest Dermatol. 1999;113(3):364–368. |
10469335 |
Full-length Thymosin Beta-4 significantly accelerates dermal wound closure and increases collagen deposition in vivo |
| Philp D et al. "Thymosin β4 promotes angiogenesis, wound healing, and hair follicle development." FASEB J. 2004;18(3):439–441. |
15037013 |
Tβ4 promotes endothelial cell migration, capillary tube formation, and hair follicle cycling in rodent models |
| Sosne G et al. "Thymosin beta 4 promotes corneal wound healing and decreases inflammation in vivo following alkali injury." Exp Eye Res. 2002;74(2):293–299. |
11950239 |
N-terminal LKKTETQ actin-binding domain mediates corneal re-epithelialization and inflammatory modulation |
Stability & Storage
| Condition |
Degradation Profile |
| Neutral pH (5.5–8.5) |
Stable; the actin-binding affinity of the LKKTETQ fragment is retained across this broad pH range |
| Repeated Freeze-Thaw |
Avoid; each freeze-thaw cycle increases risk of peptide degradation, aggregation, and loss of activity. Aliquot into single-use portions after initial reconstitution |
| Acidic pH (<4.0) |
Potential hydrolysis of peptide bonds; avoid strongly acidic buffers |
| Alkaline pH (>9.0) |
Risk of deamidation at Gln residue; degradation accelerates |
| Temperature |
Lyophilized: stable 24 months at 2–8°C, 36 months at −20°C. Reconstituted: 24 h at 4°C; freeze at −20°C for ≤30 days |
| Light Exposure |
Protect from light; store in amber vials or opaque containers |
Frequently Asked Questions
Q: What purity specifications apply to TB-500?
≥99.0% by HPLC at 214 nm with ESI-MS mass identity confirmation (±1.0 Da). Comprehensive QC includes peptide content (≥80.0%), water content (≤5.0%), acetate/TFA content (≤1.0%), endotoxin (≤1.0 EU/mg), and residual solvents within ICH Q3C limits. Full batch-specific COA with HPLC chromatogram and MS spectrum included.
Q: How should TB-500 be stored after reconstitution?
Reconstituted TB-500 is stable for 24 hours at 2–8°C. For longer storage, aliquot into single-use portions and freeze at −20°C (stable ≤30 days). Critical: avoid repeated freeze-thaw cycles which cause peptide degradation and aggregation. Use siliconized or low-retention vials for dilute solutions — TB-500 is a short linear peptide susceptible to non-specific adsorption to standard plastic labware.
Source & Purchase
For researchers requiring TB 500 with full analytical documentation including HPLC and LC-MS traces, visit the PeptideSourceHub product page for bulk pricing and specifications.
Purchase TB 500 with COA →
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