TB-500
Thymosin β4 fragment
Overview
TB-500 is a 43-residue synthetic peptide derived from Thymosin beta-4, the actin-sequestering protein expressed across essentially every mammalian cell type. Biological activity centres on actin binding via the central LKKTETQ motif, with downstream effects on cell migration, angiogenesis, and tissue regeneration, the mechanistic substrate for the published TB-500 literature on wound healing, cardiac remodelling, and tendon-ligament repair models. The 43-residue length keeps the molecule serum-stable but gastric-labile, so all documented use is via injectable routes. For 503A patient-specific compounders, TB-500 is scheduled for FDA PCAC review at the July 2026 meeting against the 503A bulks-list criteria, with the proposed indication of wound healing. Vialdyne releases TB-500 acetate as a lyophilised powder against a ≥99.0% main-peak HPLC specification. At 43 residues the sequence sits in the upper-middle of routine SPPS, synthesis is reliable but the purification regime has to work harder than for shorter peptides like BPC-157, and the standard release packet leans on peak-integration HPLC plus ESI-MS to clear closely-eluting deletion sequences. LC-MS/MS sequence verification is the recommended add-on test at any first-time pharmacy qualification: for a 43-mer, the residue-mass ambiguity of mass-spec alone is meaningfully larger than for a 15-mer, and only tandem MS demonstrates that the synthesised sequence matches the labelled one. TB-500 is dispensed either as the standalone vial or co-lyophilised with BPC-157 as the Wolverine Blend (5+5 mg per 10 mg vial standard; non-standard ratios available under change-control). Two companion pieces flesh out the procurement picture: our mechanism-and-analytics [BPC-157-vs-TB-500 comparison](/insights/bpc-157-vs-tb-500-side-by-side), and the regulatory-framing [overview of 503A vs 503B compounding pathways](/insights/503a-vs-503b-compounding-pharmacy-peptides).
Who buys this, and why
Repair peptides, BPC-157, TB-500, and related sequences, typically ship to research labs studying tissue-repair, gastrointestinal, or tendon-ligament models, and to compounding pharmacies that have validated the bulk active into their workflow. The synthesis itself is reliable, but analytical confirmation is where suppliers differ, buyers qualifying a new source should request sequence verification by tandem MS on the first batch and compare against the labelled sequence directly.
Primary buyer fit: 503A / 503B compounding pharmacies and academic and contract research laboratories.
Specifications
- CAS
- 885340-08-9
- Sequence
- SDKPDMAEIEKFDKSKLKKTETQEKNPLPSKETIEQEKQAGES
- Appearance
- White lyophilized powder
- Purity (HPLC)
- ≥ 99.0%
- Common vial sizes
- 2 mg, 5 mg, 10 mg
- MOQ
- On request
- Lead time
- 7–14 days
- Storage
- -20°C, protect from light
Documentation available on request
- Certificate of Analysis (COA)
- HPLC Chromatogram
- Mass-spec identity (ESI-MS)
- Sequence verification (LC-MS/MS)
- Water content (Karl Fischer)
- Counter-ion analysis
- SDS / MSDS
- Stability data on request
Regulatory note
Currently under FDA PCAC review (July 2026) for inclusion on the 503A bulks list, with the proposed indication of wound healing.
Frequently asked questions
What is TB-500 and how does it differ from native Thymosin beta-4?▾
TB-500 is a 43-residue synthetic peptide spanning a defined region of native Thymosin beta-4 (a 44-residue cellular protein in mammals). The synthetic sequence preserves the LKKTETQ actin-binding motif that drives biological activity. Two practical advantages distinguish synthetic TB-500 from recombinant full-length Thymosin beta-4: it is materially cheaper to produce at compounding-pharmacy scale, and it sidesteps the lot-to-lot variability inherent in cell-line-expressed biological products. For the actin-binding and tissue-regeneration endpoints that dominate the published literature, per-mass activity is functionally equivalent between the two.
Why is sequence verification more important for TB-500 than for shorter repair peptides?▾
Length is the issue. At 43 residues, TB-500 sits at the upper-middle of routine SPPS, and longer peptides accumulate single-residue deletion sequences during synthesis that elute right up against the target peak on RP-HPLC. They pass the standard purity-percentage gate but are not the molecule on the label. Mass spec resolves identity to within 0.5 Da of theoretical, but cannot distinguish a Lys-deletion at position 12 from a Lys-deletion at position 30, both have the same residue mass. Only LC-MS/MS with a full b- and y-ion ladder demonstrates positional integrity. This is the standard qualification test we recommend for any 40-plus residue peptide entering a new pharmacy's quality system.
What's the practical difference between using TB-500 alone vs. the Wolverine Blend with BPC-157?▾
Mechanistically the two peptides are not interchangeable. TB-500 works through actin sequestration, modulating cell migration and tissue remodelling. BPC-157 works through nitric-oxide-pathway modulation and growth-factor-receptor cross-talk. The complementary mechanisms are why the two get combined so frequently in repair-focused compounding protocols. The Wolverine Blend SKU presents both peptides in a single co-lyophilised vial at a 5+5 mg standard ratio (other ratios under change-control), with a single COA certifying both component purities and the in-vial ratio, which reduces the document-handling burden on the receiving pharmacy's QA file.
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