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Lynx Peptides

Full-length & fragment research

TB-500

Full-length thymosin β4 actin and cell-migration research is distinguished from short TB-500 fragment identity and metabolism. A tiny eye-drop trial adds formulation-specific human context.

Research summary

Full-length thymosin β4 and the short acetylated fragment Ac-LKKTETQ are distinct molecules. The fragment comprises residues 17–23 of the parent sequence. A published analysis identified that seven-residue fragment in a preparation labelled TB-500, showing why the name alone cannot establish which molecule a study tested. PMID 22962027

Actin is a protein used to build the cellular cytoskeleton. Full-length thymosin β4 binds actin monomers, the individual units from which filaments assemble. Binding contacts extend across the peptide chain, so the isolated short motif cannot be assumed to reproduce the full-length interaction. Literature identification of one preparation also does not verify the identity of a separate supplier batch. PMID 18327913 · PMID 22962027

Synthesis and characterization of the N-terminal acetylated 17-23 fragment of thymosin beta 4 identified in TB-500, a product suspected to possess doping potential.

Drug testing and analysis 2012

Esposito S, Deventer K, Goeman J, Van der Eycken J, Van Eenoo P

Analytical, cell and rat models

An analysed TB-500 preparation contained Ac-LKKTETQ, the acetylated seven-residue thymosin β4 fragment. Chromatography and mass spectrometry established the identity in that preparation and supported detection methods. The result concerns a fragment, not full-length 43-residue thymosin β4, and is analytical evidence rather than a demonstration of tissue repair.

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Simultaneous quantification of TB-500 and its metabolites in in-vitro experiments and rats by UHPLC-Q-Exactive orbitrap MS/MS and their screening by wound healing activities in-vitro.

Journal of chromatography. B, Analytical technologies in the biomedical and life sciences 2024

Rahaman KA, Muresan AR, Min H, Son J, Han HS, Kang MJ, Kwon OS

Analytical and rat metabolism study

Only the metabolite Ac-LKKTE produced a significant wound-closure signal among the TB-500 fragment-related compounds tested in a fibroblast assay. The parent acetylated fragment was also tracked through serum, enzyme and rat-urine experiments, with different metabolites persisting for different periods. These are fragment-specific metabolism and cell findings, not results for full-length thymosin β4.

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Effects of BPC-157 and TB-500 on Achilles tendon healing in rats: A histopathological and biomechanical study.

Joint diseases and related surgery 2026

Biçer O, Adanir O, Güleryüz Y, Balci EC, Dinçel YM, Yenigün MY, Aydin C, Bayrak BY

Rat Achilles-tendon model

The BPC-157 and TB-500 combination did not add benefit over the individual agents in an exploratory rat Achilles-tendon study. Among 32 rats divided into four groups, TB-500 had the clearest significant load-to-failure and histological findings, while the combination improved one histology score. Collagen I expression did not differ significantly between groups. The eight-animal groups and four-week follow-up limit the conclusion, and the reported TB-500 preparation still needs identity matching before comparison with a catalogue vial.

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Widely distributed residues in thymosin beta4 are critical for actin binding.

Biochemistry 2008

Au JK, Olivares AO, Henn A, Cao W, Safer D, De La Cruz EM

Molecular and analytical characterisation

Actin binding depended on residues distributed across full-length thymosin β4, not only its central short motif. Several substitutions markedly weakened association or stability of the actin complex. This helps explain why the complete molecule and an isolated fragment are distinct biochemical tools.

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Thymosin beta 4 stimulates directional migration of human umbilical vein endothelial cells.

FASEB journal 1997

Malinda KM, Goldstein AL, Kleinman HK

Cellular and animal mechanistic research

Full-length thymosin β4 promoted directional movement of cultured human endothelial cells and migration into an experimental scratch. Matrix metalloproteinase production also increased. These cell and implanted-matrix observations connect actin-related biology with vascular-cell movement, without making the assay a human wound-treatment result.

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Thymosin β4 significantly improves signs and symptoms of severe dry eye in a phase 2 randomized trial.

Cornea 2015

Sosne G, Dunn SP, Kim C

Small human trial of full-length thymosin β4 eye drops

Ocular discomfort and corneal staining were lower with a full-length thymosin β4 eye-drop preparation than with vehicle at the final follow-up in a nine-person blinded trial of severe dry eye. Treatment lasted 28 days, followed by another 28 days of observation. The very small sample and local eye-drop formulation give limited human context for thymosin β4, not an outcome established for the Lynx TB-500 vial or its shorter namesake fragments.

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Models studied

  • Full-length thymosin β4 actin and endothelial-cell experiments
  • Short TB-500 fragment identity and metabolism
  • Small trial of full-length thymosin β4 eye drops

Key findings

  • Distributed actin-binding contacts

    Contacts across the full thymosin β4 chain contribute to actin binding, making an isolated short motif a different experimental input.

  • Full-length endothelial migration

    Full-length thymosin β4 linked vascular-cell migration with matrix-enzyme measurements in experimental systems.

  • What fragment identity studies show

    The analysed TB-500 was an acetylated seven-residue fragment, not the full-length molecule specified by Lynx.

  • Fragment metabolism and a limited cell signal

    The significant fibroblast signal belonged to one fragment metabolite, leaving full-length thymosin β4 activity untested.

  • Limited human context for full-length thymosin β4

    Nine participants and a defined eye-drop preparation provide narrow human context for full-length thymosin β4.

References

  1. Synthesis and characterization of the N-terminal acetylated 17-23 fragment of thymosin beta 4 identified in TB-500, a product suspected to possess doping potential.

    Drug testing and analysis 2012

    Esposito S, Deventer K, Goeman J, Van der Eycken J, Van Eenoo P

    PMID 22962027

    View on PubMed

  2. Simultaneous quantification of TB-500 and its metabolites in in-vitro experiments and rats by UHPLC-Q-Exactive orbitrap MS/MS and their screening by wound healing activities in-vitro.

    Journal of chromatography. B, Analytical technologies in the biomedical and life sciences 2024

    Rahaman KA, Muresan AR, Min H, Son J, Han HS, Kang MJ, Kwon OS

    PMID 38382158

    View on PubMed

  3. Effects of BPC-157 and TB-500 on Achilles tendon healing in rats: A histopathological and biomechanical study.

    Joint diseases and related surgery 2026

    Biçer O, Adanir O, Güleryüz Y, Balci EC, Dinçel YM, Yenigün MY, Aydin C, Bayrak BY

    PMID 42542926

    View on PubMed

  4. Widely distributed residues in thymosin beta4 are critical for actin binding.

    Biochemistry 2008

    Au JK, Olivares AO, Henn A, Cao W, Safer D, De La Cruz EM

    PMID 18327913

    View on PubMed

  5. Thymosin beta 4 stimulates directional migration of human umbilical vein endothelial cells.

    FASEB journal 1997

    Malinda KM, Goldstein AL, Kleinman HK

    PMID 9194528

    View on PubMed

  6. Thymosin β4 significantly improves signs and symptoms of severe dry eye in a phase 2 randomized trial.

    Cornea 2015

    Sosne G, Dunn SP, Kim C

    PMID 25826322

    View on PubMed

For laboratory research use only. Content is provided for research reference and is not intended as medical or veterinary guidance.