BPC-157 and TB-500: What the Blend Actually Contains

BPC-157 and TB-500 are probably the most commonly paired compounds in the research peptide market, sold together often enough that the combination has picked up nicknames. What gets discussed far less is that one of the two names is genuinely ambiguous, and that a blend certificate carries more information than a single-compound one, if you know what to look for.

BPC-157: the straightforward one

BPC-157 is a synthetic pentadecapeptide, fifteen amino acids, sequence Gly-Glu-Pro-Pro-Pro-Gly-Lys-Pro-Ala-Asp-Asp-Ala-Gly-Leu-Val, written in the standard three-letter symbols and, by convention, from the N-terminus to the C-terminus.^[3] It corresponds to a partial sequence of a protein found in human gastric juice, which is where the name comes from: Body Protection Compound. There is one CAS number, 137525-51-0, one formula, C62H98N16O22, and a molecular weight around 1419.5 g/mol.^[1] If a certificate reports something meaningfully different, that is worth a question.

TB-500 is not one specific thing

This is the part worth understanding before you buy anything labeled TB-500.

The name is used loosely across the market for two different molecules. Some suppliers ship full-length thymosin beta-4, a 43-amino-acid peptide, CAS 77591-33-4, molecular weight roughly 4963 g/mol, N-terminally acetylated and beginning Ac-Ser-Asp-Lys-Pro.^[2] Others ship a short synthetic fragment, commonly the seven-residue Ac-LKKTETQ sequence, which weighs under 900 g/mol. Both get sold as “TB-500.”

Those are not interchangeable materials, and the difference is easy to detect if the paperwork exists: the molecular weights differ by more than fivefold. Ours is the full-length 43-amino-acid peptide, and you do not have to take our word for it. The certificate for our current blend lot names TB-500 with CAS 77591-33-4, formula C212H350N56O78S and a mass of ~4963 g/mol, right on the document.

If a listing says “TB-500” with no sequence, no CAS number and no molecular weight anywhere, there is no way to tell which molecule is in the vial. That is a paperwork problem rather than a problem with the compound.

Why they are studied together

The two appear together in the literature because they are investigated in overlapping research areas, largely around tissue repair models, angiogenesis and cell migration. They are structurally unrelated and act through different mechanisms, so pairing them is a research design choice rather than a chemical necessity. Nothing here should be read as a claim about effects in any organism; these are areas of study.

How to read a blend certificate

A blend is not a compromise on testing. Done properly, a blend certificate is simply more document: each compound gets its own identity confirmation, its own quantity check and its own purity figure. Our current BPC-157 / TB-500 lot is a four-page certificate for exactly that reason, two pages per compound.

Three things to look for on any blend certificate:

• Each compound named individually, with its own CAS number, formula and molecular weight, rather than a single line listing both names.
• A purity figure per compound. On our current lot that is 99.25% for BPC-157 and 99.31% for TB-500, each measured by UPLC with mass spectrometry confirming identity.
• Quantity per compound, so you know the fill matched the label rather than assuming it.

You can pull that document yourself. Enter the lot number from your vial and the purity and endotoxin certificates come back for that specific lot. If certificates are new to you, how to read a COA goes through one line by line, and what peptide purity actually means explains why the headline percentage is not the whole story.

Specifications

BPC-157

• Length: 15 amino acids (pentadecapeptide)
• Sequence: Gly-Glu-Pro-Pro-Pro-Gly-Lys-Pro-Ala-Asp-Asp-Ala-Gly-Leu-Val
• Molecular formula: C62H98N16O22
• Molecular weight: ~1419.5 g/mol
• CAS number: 137525-51-0

TB-500 (thymosin beta-4, full length)

• Length: 43 amino acids
• Molecular formula: C212H350N56O78S
• Molecular weight: ~4963 g/mol
• CAS number: 77591-33-4

Both are supplied as lyophilized powder and stored at -20°C, protected from light and moisture. See the individual listings for BPC-157 and TB-500, or the BPC-157 / TB-500 blend.

References

Sources are limited to identity: registry numbers, molecular formulas, masses and sequence notation. Nothing here is cited for biological activity. Each was checked on 11 August 2026.

1. LGC Standards, BPC 157 reference standard. CAS 137525-51-0, C62H98N16O22, molecular weight 1419.54. Reference standard record.
2. CAS Registry Number 77591-33-4, thymosin beta-4: C212H350N56O78S, molecular weight 4963.49, 43 residues, N-terminally acetylated. Cross-checked 11 August 2026 against a published supplier reference record. No link is given because CAS Common Chemistry carries no free public entry for this substance, which we confirmed rather than assumed, and we do not link catalogue pages as sources.
3. IUPAC and IUBMB Joint Commission on Biochemical Nomenclature, Nomenclature and Symbolism for Amino Acids and Peptides (Recommendations 1983), published 1984. Full recommendations.

Related reading

• How to Read a COA
• What Is Peptide Purity?
• Endotoxin Testing Explained
• How to Vet a Research Peptide Supplier
• Frequently Asked Questions
• All guides

For research use only. Not for human or veterinary use, ingestion, injection, or any form of in vivo administration. Not intended to diagnose, treat, cure, or prevent any disease or condition.