BPC-157 versus TB-500: the differences
Two compounds constantly discussed together and rarely distinguished: origin, chemistry, handling, and where each appears in the research literature.
BPC-157 and TB-500 are the two most requested research peptides in the UK and are constantly discussed together, which obscures how different they are: in origin, in size and chemistry, in the models the literature has studied them in, and in how they behave on the bench. This note sets out the differences neutrally, for researchers deciding which compound suits a study design or trying to read the literature on each without conflating them. All Alphex products are for laboratory and in-vitro research only.
Origin and identity
- BPC-157 is a synthetic 15-residue peptide (GEPPPGKPADDAGLV, 1419.5 g/mol) whose sequence is a fragment of a protein identified in gastric juice. It has been produced synthetically for research since the 1990s. See the BPC-157 guide.
- TB-500 is a synthetic 7-residue fragment (Ac-LKKTETQ, 889.0 g/mol) of thymosin beta-4, a 43-residue actin-binding protein present in nearly all cells. The fragment is the actin-binding motif of the parent. See the TB-500 guide.
Neither is a fragment of the other, and neither has a shared mechanism established in the literature. Their pairing is a matter of market habit, not chemistry.
Chemistry and handling
- Size: BPC-157 is 15 residues; TB-500 is 7. Both are small, water-soluble, and reconstitute easily.
- Stability: BPC-157 has no Met, Cys, Trp, Asn or Gln and is comparatively robust in solution; TB-500 has a C-terminal Gln that can deamidate on long storage. Both are supplied lyophilised as acetate salts. See deamidation and oxidation.
- Charge: BPC-157 is net acidic (three Asp/Glu, one Lys); TB-500 is net basic (two Lys, one Glu, acetylated N-terminus). This affects behaviour in buffers and on HPLC.
- UV: neither has Trp or Tyr; both are quantified at 220 nm, not 280 nm. See 220 nm versus 280 nm.
Where each appears in the literature
BPC-157 has a large preclinical literature, concentrated in a small number of research groups, predominantly rodent models of tendon, ligament, muscle and gastrointestinal injury, with mechanistic threads around angiogenesis and the nitric oxide system. Very little of it is in vitro; almost none is in humans.
TB-500 / thymosin beta-4 has a literature that must be read in two parts. The full-length protein has substantial preclinical and some early clinical work in dermal, corneal and cardiac models, and a well-characterised biochemistry as an actin-sequestering protein. The 17-23 fragment has a much smaller literature, mostly in-vitro actin-binding and cell-migration work and a handful of animal-model comparisons with the parent. Studies of the protein are not studies of the fragment.
Neither literature establishes any use outside the laboratory, and researchers should read primary sources rather than supplier summaries, this one included.
Practical differences for study design
- Molar equivalence: at equal mass, TB-500 gives about 1.6 times as many moles as BPC-157 (889 versus 1419.5 g/mol). Compare on a molar basis, with net-content correction. See calculating concentration.
- Controls: a scrambled-sequence peptide is the appropriate negative control for either; they are not controls for each other.
- Analytical: they separate cleanly on reverse-phase HPLC and have very different masses, so a mixed sample is easy to characterise.
Verification
Both are supplied by Alphex at 99+% HPLC purity (220 nm), batch-numbered, from UK stock. For TB-500 the mass-spec result (889, not 4,963) is the definitive answer to the fragment-versus-protein confusion. See how Alphex tests every batch.
Alphex research peptides are supplied for laboratory and in-vitro research by qualified researchers only. They are not authorised for human or veterinary use.
Research use only. Alphex products are supplied exclusively for laboratory and in-vitro research by qualified researchers. They are not authorised for human or veterinary use, and nothing in this note is advice on any such use.
Published 19 February 2026. Alphex reviews research notes when the testing method, the catalogue or UK guidance changes.