BPC-157 vs TB-500: How They Differ

BPC-157 and TB-500 get named together constantly, and by identity they have almost nothing in common. They trace back to unrelated parent molecules, they are very different lengths, they carry different CAS numbers, and they surface in different corners of the published research. The only real reason to line them up is that both names circulate in the same tissue-research conversations, so a plain side-by-side on what each one actually is earns its place.

This post stays on identity, chemistry, research field, and handling. It does not touch use, because neither compound has a use to describe here. Both are sold as laboratory reagents. If you want the individual write-ups, there is a full [BPC-157](/products/bpc-157) product page and a [TB-500](/products/tb-500) product page, each with its own certificate of analysis.

Where each one comes from

The two peptides descend from completely unrelated parent molecules, and that is the first place they split.

BPC-157 is a synthetic 15-amino-acid fragment with the sequence GEPPPGKPADDAGLV. The fragment is a partial sequence copied from a larger protein that was isolated from gastric juice and named Body Protection Compound by the group that first described it, which is where the letters come from. In the literature you will also see it written as PL 14736. Read the name as nomenclature inherited from the source protein, nothing more.

TB-500 is a synthetic peptide related to Thymosin Beta-4, a naturally occurring protein. The "TB" is short for Thymosin Beta. What ships under the TB-500 label is a 43-residue, N-acetylated peptide corresponding to that Thymosin Beta-4 sequence, built by synthesis rather than pulled from tissue. So one compound's lineage runs back to a gastric protein and the other's to a thymic one. Different families entirely.

Size and structure

The clearest single difference is length: TB-500 is nearly three times the size of BPC-157.

BPC-157 is 15 residues. TB-500 is 43, and it carries an acetyl group on its N-terminus, which the shorter peptide does not. That size gap shows up in every downstream number, from molecular formula to molecular weight. Here are the two identity blocks next to each other.

BPC-157:

• CAS number: 137525-51-0
• Molecular formula: C62H98N16O22
• Molecular weight: 1419.53 g/mol
• Sequence: GEPPPGKPADDAGLV (15 aa)
• Other names: PL 14736, Body Protection Compound-157

TB-500:

• CAS number: 77591-33-4
• Molecular formula: C212H350N56O78S
• Molecular weight: 4963.44 g/mol
• Sequence: Ac-SDKPDMAEIEKFDKSKLKKTETQEKNPLPSKETIEQEKQAGES (43 aa, N-acetylated)
• Related to: Thymosin Beta-4

Note the sulfur in the TB-500 formula, absent from BPC-157, and the roughly 3.5-fold difference in molecular weight. If you ever catch yourself comparing a mass-spec figure for one against a certificate for the other, these numbers are why it will not line up. The CAS number is the value that keeps them straight, since a name can be transcribed a dozen ways and a formula can be typed wrong, but the registry number cannot.

Which research field each appears in

Both are referenced in tissue-research literature, but they cluster in different sub-areas of it.

BPC-157 shows up mainly in tissue research and gastrointestinal research. TB-500, through its relationship to Thymosin Beta-4, shows up mainly in tissue research and cell-migration research. Those are subject areas, the topics under which the papers are filed. Naming the field a compound has been studied in is a statement about what researchers have looked at, not a statement about any finding.

I am not summarizing those findings here, on purpose. This category has a hard line between describing what a molecule is and describing what anyone claims it does, and a comparison post stays on the identity side of that line just as an individual primer would. If you want the actual studies, the sequences and CAS numbers above are what you search on.

How each is supplied and handled

Handling is the one place the two are basically identical.

Both ship lyophilized, meaning freeze-dried to a dry solid. Both are stored at -20C and kept out of light. Keep the vial sealed until you are working with it, limit exposure to moisture and repeated temperature swings, and handle each as the laboratory reagent it is. None of that is preparation guidance; it is storage and nothing else.

The molecular-weight gap does matter for record-keeping. A 5 mg vial of TB-500 and a 5 mg vial of BPC-157 hold very different numbers of moles, because TB-500 weighs about 3.5 times as much per molecule. If you log material by amount of substance rather than by mass, that is the conversion to get right.

Cross-checking the label

On paper, the CAS number is what separates these two: 137525-51-0 for BPC-157, 77591-33-4 for TB-500. Match that first, then the sequence, then the molecular weight. Every lot of each ships with its own third-party certificate of analysis, tested at independent third-party laboratories.

If you have not read one of these certificates before, there is a walkthrough on [how to read a peptide COA](/research/how-to-read-a-peptide-coa), plus a broader [checklist for buying research peptides in Canada](/research/buying-research-peptides-canada). Kits Peptides ships tracked from Vancouver, BC across Canada.

*All products are supplied as laboratory reagents for research use only. Not for human or veterinary use.*