BPC-157 vs TB-500: Two Repair-Pathway Peptides Compared

BPC-157 and TB-500 are the two repair-pathway peptides researchers ask us about most. They get grouped together because both are lyophilized in 5 mg vials and both appear in tissue-repair protocols — but the molecules themselves are unrelated.

Two different molecules

Property	BPC-157	TB-500
Full name	Body Protection Compound-157	Thymosin Beta-4 fragment
Origin	Gastric juice pentadecapeptide	Actin-binding domain of TB4
Molecular weight	≈ 1,419 g/mol	≈ 4,963 g/mol
Vial size	5 mg lyophilized	5 mg lyophilized
CAS	137525-51-0	885340-08-9

BPC-157 is a 15-amino-acid peptide first isolated from gastric juice. Its research footprint covers angiogenesis, tendon fibroblast activity, and gastrointestinal mucosa models. TB-500 is not a full protein — it’s the synthetic fragment of Thymosin Beta-4 containing the actin-binding domain, which is the part that shows up in cell migration and tissue-repair studies.

Where the confusion comes from

Both peptides appear in protocols that touch soft-tissue repair, so it’s natural to treat them as interchangeable. In the literature they are studied for different reasons: BPC-157 leans toward stability — it survives harsh conditions and is studied for GI and tendon work — while TB-500’s fragment design is about cellular mobility and the actin cycle. If a protocol specifies one, swapping in the other changes what is actually being studied.

Reconstitution: identical math

Both vials are 5 mg. The reconstitution calculator handles either in one preset change:

• 5 mg + 2 mL BAC water → 2,500 µg/mL
• A 250 µg dose → 10 units on a U-100 syringe

Molecular weight matters when you move from mass to molarity — compute either if your protocol calls for molar concentrations.

Practical notes

• Both are stored lyophilized at −20 °C and reconstituted with USP bacteriostatic water.
• BPC-157 is commonly referenced for its pH and temperature stability; TB-500 protocols often mention its shorter storage window once reconstituted. Always follow the Certificate of Analysis.

Full specifications: BPC-157 and TB-500.

For laboratory research use only. Not medical advice.