TB-500: Reference Overview and Reconstitution Notes

TB-500 is a man-made, short peptide fragment of thymosin beta-4. It is grouped with healing and tissue-repair research peptides and is a research-only compound that is not FDA-approved.

TB-500

What it is

TB-500 is a man-made heptapeptide (a chain of exactly 7 amino acids, the tiny building blocks that make up all proteins). Its sequence is Ac-LKKTETQ. It is taken from positions 17 to 23 of a larger natural protein called thymosin beta-4. Think of thymosin beta-4 as a necklace with 43 beads. TB-500 is just beads 17 through 23 cut from that necklace. It is a short fragment, not the full 43-amino-acid protein, even though the two names are often used as if they mean the same thing in product listings.

Research context and categorization

TB-500 falls under the category of research peptides studied for tissue repair and healing. The section of thymosin beta-4 that TB-500 copies is the part that binds to actin. Actin is a protein inside cells that gives them their shape and helps them move. Because of this connection, researchers study TB-500 in relation to how cells migrate and heal wounds. It is also studied in relation to angiogenesis (the growth of new blood vessels) and general tissue repair. These studies have been carried out in lab settings and animal models.

Investigational Status

These uses are still under investigation. Most published scientific research that specifically names TB-500 focuses on detecting it as a banned substance in sport, not on proving it works as a therapy. Human clinical data on the TB-500 fragment itself are limited. Also, products sold under the TB-500 name are not always the same chemical as the full-length thymosin beta-4 used in clinical studies. None of the repair or healing effects seen in early lab work should be read as confirmed or approved benefits.

Key point: TB-500 is a short, man-made peptide fragment of thymosin beta-4 that remains strictly investigational, with very little human clinical data.

Status

• Regulatory status: Research only. TB-500 is not FDA-approved for use in humans or animals. No drug company holds an approved indication for it. It is handled as a research chemical for laboratory use only.
• Sport status: Banned by the World Anti-Doping Agency (WADA). Thymosin beta-4 and its related compounds, including TB-500, are listed on the WADA Prohibited List under the growth factors and growth factor modulators class. They are prohibited at all times, both in and out of competition.

Reconstitution notes (general)

TB-500 is usually supplied as a lyophilized (freeze-dried) powder. Before use in the lab, you mix it with bacteriostatic water (water that contains a small amount of benzyl alcohol to stop bacteria from growing in the vial). Working out the concentration is simple: divide the milligrams of peptide by the milliliters of water you add. For example, 5 mg of powder mixed into 2 mL of water gives 2.5 mg/mL. To calculate the concentration and volumes for your specific vial, use the peptide calculator.

Dilution and handling notes (compound-specific)

Concentration Ratios

TB-500 is most often sold in 5 mg or 10 mg vials. Common reconstitution volumes produce concentrations roughly in the 1 to 5 mg/mL range. For a 5 mg vial: adding 1 mL of bacteriostatic water gives about 5 mg/mL, adding 2 mL gives about 2.5 mg/mL, and adding 5 mL gives about 1 mg/mL. The volume you choose depends on how concentrated the working solution needs to be. There is no single required volume.

Handling Best Practices

TB-500 is a short, highly water-soluble peptide, so it dissolves easily. It does not clump or turn cloudy the way some larger or oilier peptides can. Standard handling still applies: add the water slowly, aiming the stream at the inside wall of the glass vial rather than directly onto the powder. Then let the vial sit and swirl it gently until the powder fully dissolves. Do not shake the vial hard. Shaking creates foam, and that mechanical stress can damage the peptide chains. A properly mixed solution should be clear and colorless.

Handling and storage

Keep reconstituted TB-500 in the refrigerator at 2 to 8 C and away from direct light. Wipe the rubber stopper on the vial with an alcohol swab before each access, and write the mix date on the label so you can track how old the solution is.

A reconstituted solution is generally considered usable for about four weeks under refrigeration. Discard the solution if it turns cloudy or changes color, or if you see any particles or floating bits. Unopened freeze-dried powder is more stable but should also be kept cold and out of light.

Related reading

• Testagen
• Thymalin
• Thymosin Alpha-1
• How Reconstitution Works
• How Long Does a Reconstituted Vial Last?

Tools and supplies

• peptide calculator
• Bacteriostatic Water 30 ml
• Gansulin Metal Reusable Pen
• 3 ml Glass Cartridges (10-pack)
• Complete Starter Kit

Reminder: research and educational reference only. Preppin Peppers sells hardware and materials, not peptides. Not medical, dosing, or health advice, not evaluated by the FDA, and not intended for human or animal use.

Frequently asked questions

What is the difference between TB-500 and thymosin beta-4?

Thymosin beta-4 is a full 43-amino-acid protein; TB-500 is a synthetic 7-amino-acid fragment (residues 17-23) derived from it. The two are chemically distinct, though product listings often conflate them.

How do you reconstitute TB-500 lyophilized powder for lab use?

Add bacteriostatic water to the vial and divide mg of peptide by mL of water added to get concentration. For example, 5 mg + 2 mL = 2.5 mg/mL. Swirl gently; do not shake.

Is TB-500 banned in sport?

Yes. WADA lists thymosin beta-4 and related fragments, including TB-500, on its Prohibited List under growth factors and growth factor modulators, banned at all times in and out of competition.

What the research community gets wrong about TB-500

• TB-500 and thymosin beta-4 are not the same molecule. TB-500 is a short synthetic peptide (Ac-LKKTETQ, the stretch at positions 17 to 23), while thymosin beta-4 is the full protein of about 43 to 44 amino acids. Product listings and forum posts often treat the two names as interchangeable, but they are chemically distinct compounds. Results reported for one should not be assumed for the other.
• The "repair peptide" reputation comes mostly from the full protein, not the fragment. Much of what people cite comes from cell and animal work on thymosin beta-4. The published literature that names TB-500 specifically is largely about detecting it as a banned substance in sport, not controlled evidence that the fragment does anything in a body. On the bench it is a research chemical, nothing more.
• A clear, colorless vial only proves the powder dissolved. TB-500 is small and very water soluble, so it goes into solution fast and looks clean. Clarity does not tell you the peptide chain is still intact. Rough shaking that creates foam can damage the peptide even when the liquid still looks perfect, so gentle swirling matters more than the visual.
• The labeled milligrams are not always net peptide mass. Freeze-dried vials often contain acetate salt and a little leftover water along with the peptide. If you plug the label value straight into a concentration calculation and assume it is 100 percent pure peptide, your real concentration can come out lower than the number on paper.

From our bench: If you reconstitute TB-500 in your lab, we would like your real numbers. Tell us the labeled vial size, how many milliliters of bacteriostatic water you added, and about how long the powder took to go fully clear with gentle swirling (no shaking). Did the solution stay clear over its refrigerated life, and if it ever changed, on what day did you first notice it? Send your logged observations and we may add them, with credit, to this page.

Sources

1. Bacteriostatic Water for Injection, USP , FDA/DailyMed label (0.9% benzyl alcohol)
2. Duerkop et al., Biotechnol J 2018 , Impact of Cavitation, High Shear Stress and Air/Liquid Interfaces on Protein Aggregation
3. Sigma-Aldrich (Merck) , Handling and Storage Guidelines for Peptides and Proteins
4. PubChem: TB-500 (CID 62707662), synthetic thymosin beta-4 fragment Ac-Leu-Lys-Lys-Thr-Glu-Thr-Gln-OH
5. UniProt P62328 (TMSB4X): Thymosin beta-4 binds and sequesters G-actin monomers and inhibits actin polymerization