TB-500 is a synthetic version of a naturally occurring protein fragment called thymosin beta-4. It comes as a white lyophilized powder — that means freeze-dried — and needs to be kept frozen until use in the lab. A legitimate batch will have a certificate of analysis (COA) showing purity above 98% from a third-party lab.
What Is TB-500 (Thymosin Beta-4)
TB-500 is a 43-amino-acid peptide. Thymosin beta-4 occurs naturally in the body, and researchers study it in laboratory settings to understand how cells move and organize at a molecular level. TB-500 is the synthetic version of the active sequence from that protein, used in in vitro research.
It is not the same as thymosin beta-4 isolated from animal tissue. TB-500 is synthesized from scratch in a lab, so the source is consistent and the sequence is defined.
You will sometimes see it listed as Tβ4 or TB500. All three refer to the same compound.
What Form Does TB-500 Come In
TB-500 arrives as a lyophilized white powder in a sealed vial — typically 2 mg, 5 mg, or 10 mg per vial. Lyophilization means the water was removed by freeze-drying, which dramatically slows breakdown. In powder form, the peptide is stable for much longer than it would be in solution.
In laboratory preparation, the powder is reconstituted — dissolved — with bacteriostatic water. Bacteriostatic water contains 0.9% benzyl alcohol, which prevents bacterial growth and extends the usable life of the solution once it is mixed.
TB-500 Storage Temperature
Store unreconstituted TB-500 powder at or below -20°C — a standard lab or chest freezer. At that temperature a sealed vial is stable for 24 months or longer.
Refrigerator temperature (2–8°C) works for short-term storage of the dry powder, up to a few weeks, but is not ideal for anything longer. Room temperature degrades the peptide noticeably within days.
Once TB-500 is reconstituted into solution, the rules change:
- Refrigerator (2–8°C): Use within 4 to 6 weeks.
- Freezer (-20°C): Up to 3 months if you freeze in aliquots — small divided portions — so you are not repeatedly freezing and thawing the same vial.
- Room temperature: Not suitable. Use within a few hours if left out.
Repeated freeze-thaw cycles are damaging. Every time a peptide solution freezes and thaws, ice crystals form and can disrupt the structure. If a research protocol spans weeks, split the reconstituted solution into single-use aliquots before freezing.
Keep vials away from light. UV exposure breaks peptide bonds. Amber vials help, but a dark freezer box does the same job.
TB-500 COA: What to Look For
A COA — certificate of analysis — is the lab document that tells you what is actually in the vial. For TB-500, you want to see four things:
- Purity: Should be ≥98% by HPLC. HPLC is a separation technique that measures how much of the sample is the compound you want versus everything else.
- Identity confirmation: Mass spectrometry (MS) confirms the molecular weight matches TB-500. The correct molecular weight is approximately 4963 Da.
- Sequence verification: Some COAs include this; it confirms the amino acid sequence is correct, not just that something at the right mass is present.
- Testing lab: The COA should come from a third-party lab, not the manufacturer’s internal quality team. Third-party means an independent facility with no financial stake in the result.
Check that the lot number on the COA matches the lot number printed on your vial. A generic COA not tied to a specific batch tells you nothing about what is in the vial you received.
Some suppliers post COAs as PDFs on their product pages. If the document has no lot number, no date, and no lab name, it is not a COA — it is a formatted number.
Practical Summary
TB-500 is a freeze-dried synthetic peptide that mirrors a natural protein fragment studied at the cellular level. Keep dry powder frozen at -20°C, reconstitute with bacteriostatic water, and use the solution within 4 to 6 weeks from the fridge. Before beginning any laboratory work, check the COA: 98%+ purity by HPLC, mass confirmed by MS, lot number matching the vial, and a named third-party lab. Those four checks confirm the vial contains what it says it does.
NXT Labs products are sold strictly as research chemicals for in vitro research, laboratory testing and analytical purposes only, and are not intended for use in any human or animal application.
NXT Labs supplies research peptides for laboratory use. Browse the full range or view current Certificates of Analysis.
