Single component
TB-500
Thymosin β4 fragment (Ac-LKKTETQ)
A seven-amino-acid fragment of thymosin β4, acetylated at the N-terminus. TB-500 is not a separate molecule from thymosin β4 — it is a short active region of it. Thymosin β4 itself is a 43-residue protein identified in 1990 as the main intracellular G-actin-sequestering peptide in most vertebrate cells.
Identity
The molecule.
- Formula
- C38H68N10O14
- Molecular weight
- 889.01 · free peptide
- Sequence
- N-Acetyl-Leu-Lys-Lys-Thr-Glu-Thr-Gln
- CAS number
- 885340-08-9
Solubility
How much water it needs.
Source: MedChemExpress product page (opened 2026-08-20)
Cross-check: 200 ÷ 889.01 × 1000 = 224.97 mM — matches the stated molarity exactly
Used in the calculatorThe solver treats 200 mg/mL as the ceiling for TB-500 and will not return a water volume that puts the solution above it.
Storage
Keeping it.
Powder: −80°C for two years, −20°C for one year, sealed and away from moisture and light. In solution: −80°C six months, −20°C one month. All four are laboratory figures — none of them describes a domestic fridge.
We print no beyond-use date. Why that number is missing
The papers
What the research studied.
Every paper here is on PubMed and you can open it yourself. They all studied TB-500 on its own, not in a blend, and mostly in animals.
- Mendias CL, Awan TM2026Sports MedicineReview
Safety and Efficacy of Approved and Unapproved Peptide Therapies for Musculoskeletal Injuries and Athletic Performance
Reviews the pharmacology, safety profile and regulatory status of twelve peptides sold direct to patients — BPC-157, GHK-Cu and TB-500 among them. Describes the market in unapproved compounds as operating largely outside regulatory oversight.
PMID 41966639 → - Hannappel E2007Annals of the New York Academy of SciencesReview
beta-Thymosins
Traces what thymosin beta-4 actually is. Identified in 1990 as the main intracellular G-actin-sequestering peptide in most vertebrate cells. TB-500 is a fragment of this protein, not a separate molecule.
PMID 17468232 →
The name
What else it gets called.
TB-500 is the short form; the full name is Thymosin β4 fragment (Ac-LKKTETQ). Suppliers and forum posts use these interchangeably and search engines treat them as separate things, so a figure you found under one of the other names was still about this molecule.
- TB500
- TB 500
- thymosin beta-4 fragment
What we could not source
The gaps, named.
Every figure above says where it came from. These are the ones we went looking for and could not find. Each one ends with what we do about it. Admitting you do not know something and then carrying on regardless is not admitting anything.
How long TB-500 keeps once mixed, in a normal fridge
Suppliers give you storage conditions for the dry powder in a −20 °C freezer. Nothing we found says anything about a mixed vial sitting at 2–8 °C.
What we do So we print no use-by date and no countdown, anywhere on this site or in anything you download.
Where it appears
Blends that contain TB-500.
Also written as TB500 · TB 500 · thymosin beta-4 fragment.
TB-500 is a research chemical, not an approved medicine. This page describes the molecule and how to handle it; it makes no claim about what TB-500 does. Not medical advice.