Regenerative research peptides · Reference
TB-500
Synthetic 43-residue peptide (thymosin β4) · Also known as Thymosin β4 (synthetic), Tβ4, Thymosin beta-4 acetate
TB-500 is the synthetic form of thymosin β4, a 43-residue actin-sequestering peptide studied in preclinical models of tissue repair and angiogenesis. The long backbone, a single oxidation-prone methionine, and several aspartate-adjacent positions make a basic identity check insufficient — independent purity verification is what separates a clean batch from one carrying deletion and oxidation products.
Chemistry at a glance
- CAS
- 77591-33-4
- Formula
C212H350N56O78S- Avg. MW
- 4963.44 Da
- Monoisotopic
- Not published — confirmed per batch by LC-HRMS
- Sequence
SDKPDMAEIEKFDKSKLKKTETQEKNPLPSKETIEQEKQAGES
Chemistry summary only. CertikLabs does not publish dosing, administration, or clinical guidance for any peptide.
Structure and chemistry
TB-500 is a linear 43-amino-acid peptide with the one-letter sequence SDKPDMAEIEKFDKSKLKKTETQEKNPLPSKETIEQEKQAGES. The molecular formula of the free acid is C212H350N56O78S with an average molecular weight of approximately 4963.44 Da. CAS registry: 77591-33-4.
The sequence is identical to mature human thymosin β4 and is commonly supplied as the N-terminally acetylated form. The single methionine at position 6 is the most reactive site under storage and processing; the actin-binding LKKTETQ motif near positions 17–23 is the structural feature most often referenced in the mechanism literature.
Synthesis and where impurities come from
TB-500 is produced by Fmoc solid-phase peptide synthesis. Three classes of impurity dominate a real batch:
- Length variants. A 43-residue backbone accumulates deletion sequences and C-terminal truncations across the long Lys/Glu-rich middle region, especially after Lys-Lys and Glu-Lys segments where coupling efficiency drops.
- Met(6) oxidation. Methionine readily oxidizes to the sulfoxide (Δ+16 Da) and, less commonly, the sulfone (Δ+32 Da). These variants co-elute closely with the main peak and require an extracted-ion-chromatogram screen by LC-MS to quantify.
- Aspartate-adjacent rearrangements. Aspartimide formation at Asp-Lys and Asp-Met segments under repeated piperidine deprotection generates α- and β-aspartyl isomers and racemized D-Asp.
See common peptide impurities for the full taxonomy across all peptide classes.
How CertikLabs verifies TB-500
The standard CertikLabs panel for a TB-500 batch:
- RP-HPLC purity (C18, 0.1% TFA / MeCN, UV 214 nm)
- LC-HRMS identity (ESI-Q-TOF, deconvoluted average mass against C212H350N56O78S)
- Tryptic peptide mapping with LC-MS/MS for sequence confirmation
- Quantitative AAA for content
- Met-oxidation screen by extracted-ion chromatograms (Δ+16, +32 Da)
- Size-exclusion HPLC for aggregates
Each method, including column, mobile phase, gradient, and detection conditions, is reported on the Certificate of Analysis. See how to read a peptide COA for what every section should contain.
Published mechanism (literature summary)
Thymosin β4 binds monomeric G-actin and regulates the G/F-actin equilibrium. Published preclinical work describes pro-angiogenic, anti-inflammatory, and cell-migration effects mediated via the actin cytoskeleton and downstream Ac-SDKP fragment release. No clinical efficacy or safety claims are made here.
Primary sources:
- Goldstein A.L. et al., Thymosin β4: a multi-functional regenerative peptide.(PMID 22372513)
- Crockford D. et al., Thymosin beta-4: structure, function, and biological properties supporting current and future clinical applications.(PMID 20955195)
CertikLabs does not publish dosing, administration routes, or clinical recommendations for TB-500 / thymosin β4.
Stability and storage (chemistry only)
Lyophilized TB-500 is generally stable at -20°C, protected from light and moisture. In solution it is sensitive to Met(6) oxidation and surface adsorption; pH, container material, and oxygen exposure all influence the rate of degradation. Any working solution should be re-verified analytically rather than assumed stable based on storage time alone.
Frequently asked questions
What is TB-500?
TB-500 is the synthetic version of thymosin β4 (Tβ4), a 43-amino-acid actin-sequestering peptide first isolated from calf thymus. Sequence SDKPDMAEIEKFDKSKLKKTETQEKNPLPSKETIEQEKQAGES, CAS 77591-33-4, molecular formula C212H350N56O78S, average mass approximately 4963 Da. It is a research compound; CertikLabs verifies chemistry only and does not publish dosing or clinical guidance.
How is TB-500 purity tested?
Purity is measured by reverse-phase HPLC on a C18 column with a TFA / acetonitrile gradient and UV detection at 214 nm. Identity is confirmed by LC-HRMS with deconvolution against the theoretical average mass, and tryptic peptide mapping is used to verify the full sequence. The complete method (column, gradient, detection) is reported on the Certificate of Analysis.
What are the most common TB-500 impurities?
Deletion and truncation sequences from a long 43-residue backbone, methionine-6 oxidation (sulfoxide and sulfone variants, Δ+16 and +32 Da), aspartimide formation at Asp-Lys / Asp-Met segments, deamidation at Asn / Gln, aggregates, and residual counter-ion (TFA or acetate). These are the analytes a properly designed RP-HPLC + LC-MS panel must resolve from the main peak.
Is TB-500 the same as thymosin β4?
In current research-peptide supply, 'TB-500' is most commonly the full synthetic thymosin β4 sequence (often acetylated at the N-terminus). Historically the name was associated with shorter active fragments; today, market usage and CAS 77591-33-4 refer to the full 43-mer. CertikLabs reports the exact sequence and observed mass on every certificate so the supplied material is unambiguously characterized.
Published 2026-05-16