TB-500 is a synthetic peptide that reproduces the actin-binding region of thymosin beta-4, a small protein found across cell types, and it is studied for actin sequestering and cytoskeletal dynamics. Celyfe carries it at 15mg per 3ml cartridge in the WOLVERINE, GLOW and KLOW pens, always paired with BPC-157. This page covers what TB-500 is, how the pens carry it, what the listed literature covers and where it sits next to the NAD+ Precision Pen.
What is TB-500?
Thymosin beta-4 is a naturally occurring 43-amino-acid protein. TB-500 is the market name for a shorter synthetic peptide made from its actin-binding region, with the formula C38H68N10O14, molecular weight 889.0 g/mol and CAS number 885340-08-9. Like other research peptides it is produced by solid-phase peptide synthesis and characterised by mass spectrometry for identity and HPLC for purity.
The central property studied in thymosin beta-4 research is binding to monomeric actin, known as G-actin. Actin cycles between single monomers and the long filaments, F-actin, that make up much of a cell's cytoskeleton. By holding a pool of monomers in reserve, thymosin beta-4 acts as what researchers call an actin-sequestering protein, and that mechanism is the reason TB-500 appears in cell-migration and cytoskeletal-remodelling studies. The guide What is TB-500? goes further into the actin chemistry.
How TB-500 is used in the Celyfe system
Celyfe does not offer a single-compound TB-500 pen. The peptide is carried at 15mg per pre-filled 3ml cartridge in three combination pens, each pre-mixed, dispensing 0.01ml per click across 300 clicks. The published WOLVERINE certificate (batch C26071, a third-party HPLC report from Analiza Białek on a sample Celyfe supplied) reports 99% purity for each peptide and a measured content of about 91% of label for BPC-157 and 85% for TB-500; it does not include mass spectrometry. Certificates for the GLOW and KLOW pens are being re-issued and are not yet published, so no GLOW or KLOW test result is claimed here.
- WOLVERINE Pen: TB-500 15mg with BPC-157 15mg at a 1:1 mass ratio, 30mg in total, 0.100mg per click.
- GLOW Pen: the same pair plus GHK-Cu 75mg, 105mg in total, 0.350mg per click.
- KLOW Pen: the GLOW set plus KPV 15mg, 120mg in total, 0.400mg per click.
What the research literature covers
The sources below include two primary papers on thymosin beta-4 and actin, Safer et al. 1991 (J Biol Chem) and Cassimeris et al. 1992 (J Cell Biol), a doping-control study identifying TB-500 as a synthetic version of an active region of thymosin beta-4 (Ho et al. 2012), and a 2025 Arthroscopy editorial commentary, Injectable Therapeutic Peptides - An Adjunct to Regenerative Medicine and Sports Performance?, which is an opinion piece rather than a study.
The guide describes this body of work as cell biology and preclinical animal-model research using tools such as time-lapse microscopy and scratch-wound assays. It describes mechanisms observed in the laboratory and is not evidence of an effect in human use. TB-500 is not an approved medicine, and every Celyfe pen is supplied for in-vitro research use only.
Handling, storage and quality
The three TB-500 pens are pre-mixed solutions. Refrigerate at 2 to 8 degrees Celsius on arrival, keep sealed and away from light, and never freeze, because freeze-thaw stress damages peptides in solution. Prime the pen before first use and draw using aseptic technique. No bacteriostatic water or reconstitution is needed.
A certificate of analysis for a combination pen should report results separately for TB-500 and for each other component. The published WOLVERINE certificate (batch C26071, a third-party HPLC report from Analiza Białek on a sample Celyfe supplied) reports 99% purity for each peptide and a measured content of about 91% of label for BPC-157 and 85% for TB-500; it does not include mass spectrometry. The COA guide explains how to read HPLC and mass spectrometry results in general.
Key takeaways
- •Thymosin Beta-4 fragment (TB-500) is a peptide.
- •Library note: Thymosin beta-4 fragment studied for actin and cytoskeletal dynamics.
- •Carried in: GLOW Pen, KLOW Pen, WOLVERINE Pen at 15mg per pre-filled 3ml cartridge.
- •TB-500 is a regulated compound - this page is educational, not medical advice.
This page is informational and not medical advice. TB-500 is a regulated compound. Celyfe pens are supplied strictly for in-vitro laboratory research and nothing here is guidance on use in humans or animals.
At a glance
- Class
- Peptide
- Full name
- Thymosin Beta-4 fragment (TB-500)
- Per cartridge
- 15mg
- Format
- Pre-filled 3ml pen cartridge
Role in the library
Thymosin beta-4 fragment studied for actin and cytoskeletal dynamics.
Used in
Compared with
Frequently asked questions
Sources
- WOLVERINE Pen (product page)
- GLOW Pen (product page)
- KLOW Pen (product page)
- NAD+ Precision Pen (product page)
- Guide: What is TB-500?
- Guide: What is the WOLVERINE Pen?
- Guide: How to store research peptides
- Guide: What is a certificate of analysis?
- Guide: Are peptides legal in the UK?
- Compare: BPC-157 vs TB-500
- Compare: WOLVERINE Pen vs GLOW Pen
- Safer D et al. Thymosin beta 4 and Fx, an actin-sequestering peptide, are indistinguishable. J Biol Chem, 1991. PMID 1999398
- Cassimeris L et al. Thymosin beta 4 sequesters the majority of G-actin in resting human polymorphonuclear leukocytes. J Cell Biol, 1992. PMID 1447300
- Ho EN et al. Doping control analysis of TB-500, a synthetic version of an active region of thymosin β4, in equine urine and plasma by liquid chromatography-mass spectrometry. J Chromatogr A, 2012. PMID 23084823
- DeFoor MT et al. Injectable Therapeutic Peptides - An Adjunct to Regenerative Medicine and Sports Performance? (Arthroscopy, 2025, editorial commentary)
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