BPC-157 vs TB-500 compares two synthetic research peptides that are often named together and share almost nothing chemically. BPC-157 is a fifteen-residue peptide taken from a protein found in gastric juice. TB-500, as registered in PubChem, is a seven-residue acetylated fragment of thymosin beta-4, an actin-binding protein found in nearly every cell.

They differ in length, sequence, mass, charge, and parent molecule. The published research on each is also built differently: BPC-157 has its own body of cell and animal studies, while much of the biology connected to TB-500 was measured on its parent protein.

This article sets the two molecules side by side and stays on the chemistry and the laboratory record. Janera Science supplies both compounds with lot-specific documentation, and the closing section explains how a researcher can confirm which one is in a vial.

BPC-157 vs TB-500 at a Glance

BPC-157 and TB-500 are unrelated sequences from unrelated parent proteins, and every core property in the table below differs between them. The identity data comes from PubChem's compound records for each peptide (PubChem, 2026; PubChem, 2026).

The table shows why the two names should never be used interchangeably. Even the simplest identity check, molecular weight, separates them by 530.5 g/mol.

Where BPC-157 and TB-500 Come From

BPC-157 is a partial sequence of a protective protein isolated from human gastric juice, while TB-500 reproduces the central actin-binding region of thymosin beta-4. The two parents come from different parts of biology, and that shapes everything downstream.

BPC-157: a fragment of a gastric protein

BPC stands for body protection compound. The fifteen-residue peptide BPC-157 is a partial sequence of body protection compound, a protein discovered in and isolated from human gastric juice (Journal of Applied Physiology, 2011). It is described as stable in human gastric juice and also appears in the literature under the development designation PL 14736 (Current Pharmaceutical Design, 2011).

Our BPC-157 molecular structure article covers its sequence, identifiers and synthesis in more depth.

TB-500: a fragment of an actin-binding protein

Thymosin beta-4 is a 43-amino-acid protein (FASEB Journal, 2010) and the major actin-sequestering molecule in eukaryotic cells, meaning it binds single actin units and holds them out of the filaments that form the cell's internal scaffold (Trends in Molecular Medicine, 2005). Its PubChem record gives a molecular weight of 4,963 g/mol (PubChem, 2026).

TB-500 is far smaller. Its PubChem record (CAS 885340-08-9) is Ac-Leu-Lys-Lys-Thr-Glu-Thr-Gln, and analytical work published in 2012 identified this same species, the N-terminal acetylated 17 to 23 fragment of human thymosin beta-4, in a TB-500 product (Drug Testing and Analysis, 2012). The name is not always used that precisely, which is one more reason the sequence on a certificate matters. The full distinction between the fragment and its parent is set out in our article on TB-500 and thymosin beta-4 chemistry.

How the Two Structures Differ

BPC-157 is a longer, proline-rich, acidic chain with a free N-terminus, while TB-500 is a short, proline-free, lysine-containing fragment with an acetyl cap. Each of those features follows directly from the sequence.

• Length and mass. At fifteen residues and 1,419.5 g/mol, BPC-157 is about 1.6 times the mass of TB-500 at seven residues and 889.0 g/mol.

• Proline content. BPC-157 contains four prolines, three of them in an unbroken run near the N-terminus (Pro-Pro-Pro). Proline restricts how a peptide backbone can bend, so a run of three imposes a rigid segment on the chain. TB-500 contains no proline at all.

• Charge. BPC-157 carries three acidic residues (one glutamic acid and two aspartic acids) against one basic lysine, giving it a net negative charge near neutral pH. TB-500's acetylated N-terminus carries no charge, and its two lysines balance its glutamic acid and C-terminal carboxyl group, leaving it close to neutral.

• N-terminal acetylation. TB-500 carries an acetyl group on its first residue, as the native thymosin beta-4 protein does at its own N-terminus. BPC-157 has a free amino group.

If the three-letter residue codes are unfamiliar, our guide to peptide nomenclature explains how sequences like these are written and read.

What Published Research Has Measured: BPC-157 vs TB-500

Only one published laboratory study we found tests BPC-157 and TB-500 in the same experiment, an exploratory 2026 rat study; everything else has to be compared literature to literature. The two bodies of work also differ in kind. All of the studies described below are laboratory research in cell or animal models.

The one head-to-head study: a 2026 rat tendon model

A 2026 study assigned 32 rats with a surgically repaired Achilles tendon to four groups of eight: control, BPC-157, TB-500, and the two combined. After four weeks, both peptide groups showed higher maximum load to failure than controls, a difference that reached statistical significance only in the TB-500 group. On histological scoring, the TB-500 group differed significantly from controls while the BPC-157 group did not, and the combined group showed no additional effect over either peptide alone (Joint Diseases and Related Surgery, 2026).

The authors describe the work as exploratory, and it is a single small study in one model. Its summary also describes TB-500 only as synthetic thymosin beta-4 without giving a sequence, which is the identity question the documentation section below returns to.

BPC-157: studies on the peptide itself

BPC-157 has been tested directly in cell culture and in animal models, which gives it a literature specific to the fifteen-residue molecule.

• Tendon fibroblasts in culture. In rat Achilles tendon explants and cultured tendon fibroblasts, BPC-157 accelerated fibroblast outgrowth from the explants and increased cell survival under oxidative stress, without directly changing cell proliferation. It increased fibroblast migration in a concentration-dependent way, induced F-actin formation, and raised phosphorylation of the signalling proteins FAK and paxillin (Journal of Applied Physiology, 2011).

• Gene expression. A follow-up cDNA microarray study in the same cell type found growth hormone receptor among the most strongly up-regulated genes, with concentration- and time-dependent increases at both the messenger RNA and protein levels (Molecules, 2014).

• Metabolism in animals. A pharmacokinetic study in rats and beagle dogs, using tritium-labelled BPC-157 in rats, found the peptide was rapidly broken down into small peptide fragments and then single amino acids, with urine and bile as the main excretion routes (Frontiers in Pharmacology, 2022).

TB-500: a literature built mostly on its parent protein

Published work on the Ac-LKKTETQ fragment itself is limited. One fragment-specific paper is analytical: it identified the fragment in TB-500, prepared it by solid-phase synthesis, and suggested an analytical strategy to detect it in plasma and urine (Drug Testing and Analysis, 2012).

In the sources we reviewed, much of the biology connected to TB-500 was measured on full-length thymosin beta-4 or on short sequences mapped within it.

• Active-site mapping. A 2010 review of thymosin beta-4 attributes separate activities to separate short sequences in the protein. It links a short sequence containing LKKTETQ, the central actin-binding domain, with cell migration and angiogenesis (FASEB Journal, 2010).

• A caution from fragment studies. In a DNase I inhibition assay, full thymosin beta-4 sequestered G-actin at a one-to-one ratio, while the 13 to 43 and 24 to 43 fragments did not inhibit actin polymerisation. The authors concluded that features before residue 13 are required for that function (Biological Chemistry Hoppe-Seyler, 1993).

That second finding is the practical lesson for anyone reading the TB-500 literature. A fragment does not automatically carry every property of its parent, so a result measured on the 43-residue protein describes the protein, and the seven-residue fragment needs its own data.

Where the two literatures meet: the actin cytoskeleton

Both literatures touch the actin cytoskeleton from different directions. Thymosin beta-4's defining property is binding single actin units and holding them out of filaments. BPC-157, in the tendon fibroblast work, was associated with increased formation of filamentous actin and activation of the FAK-paxillin pathway that links the cell to its surroundings (Journal of Applied Physiology, 2011).

The overlap is in the system studied and stops there. The mechanisms are different, the molecules are different, and the single side-by-side study measured tissue-level outcomes without examining either mechanism.

Why Pairing BPC-157 and TB-500 Creates a Documentation Risk

BPC-157 and TB-500 are routinely discussed as a pair, and both literatures include cell migration and tissue-model work, yet their structures are unrelated. That combination of shared context and different chemistry is exactly where record-keeping errors start.

Two compounds that are discussed as a set can be confused at ordering, labelling, or record-keeping, and the consequences are larger here than for most pairs because the two molecules have nothing in common at the sequence level. Recording the exact compound, sequence and lot number for every experiment removes that ambiguity.

Telling BPC-157 and TB-500 Apart on a Certificate of Analysis

A lot-specific certificate of analysis is how a researcher confirms which of the two compounds is in a vial and at what purity. Check that the certificate names the correct compound and that its lot number matches the number printed on the vial.

High-performance liquid chromatography (HPLC) separates a sample into its components and reports purity as the share of the main peak. Janera Science's lot-specific certificates report HPLC purity and assay, plus heavy metal screening, endotoxin and sterility results for each batch. You can compare the posted certificates for BPC-157 and TB-500 on our lab results page, and our guide to reading a COA walks through each field.

BPC-157 and TB-500 are both available from Janera Science as part of our range of high-purity research peptides. Every lot is independently tested before release, and our How Janera Tests page sets out what each test covers.

Frequently Asked Questions

What is the difference between BPC-157 and TB-500?

BPC-157 is a fifteen-residue peptide from a protein found in human gastric juice, with a molecular weight of 1,419.5 g/mol. TB-500 is a seven-residue acetylated fragment, Ac-LKKTETQ, of the actin-binding protein thymosin beta-4, with a molecular weight of 889.0 g/mol (PubChem, 2026; PubChem, 2026). Their sequences, charge and parent molecules are unrelated.

Is TB-500 the same as thymosin beta-4?

No. Thymosin beta-4 is a 43-amino-acid protein. TB-500, as registered in PubChem and as identified in a 2012 analysis of a TB-500 product, is a synthetic seven-residue fragment corresponding to residues 17 to 23 of that protein, with an acetylated N-terminus (Drug Testing and Analysis, 2012). A property measured on the full protein does not automatically apply to the fragment.

Have BPC-157 and TB-500 been compared in the same study?

Once in a laboratory study, as far as we could find. An exploratory 2026 study in 32 rats compared BPC-157, TB-500 and the two combined in a repaired Achilles tendon model. The TB-500 group showed the only statistically significant biomechanical difference from controls, and the combination added nothing over either alone (Joint Diseases and Related Surgery, 2026).

Why does BPC-157 contain so many prolines?

Four of BPC-157's fifteen residues are proline, three of them in a row near the N-terminus. That is simply its native sequence. Proline restricts how a peptide backbone can bend, so the run of three gives that part of the chain a rigid shape.

What does the "Ac" in Ac-LKKTETQ mean?

"Ac" means the N-terminus carries an acetyl group. Native thymosin beta-4 is acetylated at its own N-terminus, residue 1. In TB-500 the acetyl group sits on leucine, residue 17 of the parent protein, because the fragment begins there.

How can a researcher confirm which peptide is in a vial?

Check that the lot-specific certificate of analysis names the correct compound and that its lot number matches the vial. The two peptides also differ in molecular weight by 530.5 g/mol, so their identity data cannot be confused on paper. Janera Science posts lot-specific certificates for both compounds.

Key Takeaways

• BPC-157 and TB-500 are unrelated molecules: a fifteen-residue gastric-protein fragment and a seven-residue acetylated fragment of thymosin beta-4.

• Their identity data differs sharply: C62H98N16O22 at 1,419.5 g/mol for BPC-157, and C38H68N10O14 at 889.0 g/mol for TB-500 (PubChem, 2026; PubChem, 2026).

• BPC-157 is proline-rich and acidic; TB-500 is proline-free, acetylated and close to neutral.

• BPC-157 has a literature on the peptide itself, including tendon fibroblast and metabolism studies (Journal of Applied Physiology, 2011).

• One exploratory 2026 rat study compared the two directly and found the only significant biomechanical difference in the TB-500 group (Joint Diseases and Related Surgery, 2026).

• Much of the other TB-500-related biology was measured on full thymosin beta-4, and fragment studies show a fragment does not automatically share its parent's properties (Biological Chemistry Hoppe-Seyler, 1993).

All Janera Science compounds are supplied strictly for in-vitro laboratory research use only. They are not for human or veterinary use and have not been evaluated by the FDA.