BPC-157 and TB-500: structural comparison

Both compounds are synthetic peptides whose sequences derive from larger naturally occurring proteins, but the proteins are unrelated to each other.

BPC-157's sequence corresponds to a partial region of body protection compound, a protein identified in gastric juice. The name is an abbreviation of that parent, and the number designates the specific fragment catalogued rather than a residue position.

TB-500's sequence derives from thymosin beta-4, a 43-amino-acid protein. The distinction between the two names matters: thymosin beta-4 is the full-length protein, TB-500 is the shorter synthetic construct built from its characterized region. Listings that name both are recording a sequence relationship, not two names for one molecule.

Neither compound carries a lipid modification, a non-proteinogenic residue or a cyclisation. Both are linear peptides with free termini.

That places them in a different structural category from the engineered analogues elsewhere in the catalogue, where such modifications are the defining feature. A fragment reproducing a natural sequence and an analogue engineered away from one are different kinds of molecule even when both are described as synthetic peptides.

Structural simplicity has a practical consequence in analysis: short unmodified peptides generally give cleaner chromatograms, and where impurities appear they are typically deletion sequences missing a single residue rather than mis-modified material.

Both are components of three HEEZ blends. Wolverine pairs them at a published 5 mg each in a 10 mg vial — the only blend in the catalogue that publishes its split. GLOW and KLOW both contain them alongside other components, with no per-component split published for either.

Both are also stocked as single-compound listings, so their individual certificates and specifications are available independently of any blend.

The format difference is that BPC-157 is stocked in two vial masses, 5 mg and 10 mg, while TB-500 is stocked in a single 10 mg format.

Handling is effectively identical for the two. Both are supplied lyophilized, both are ambient-stable in transit so neither requires a cold chain, and both go to refrigeration on arrival protected from light.

Reconstitution follows the same arithmetic: concentration equals mass divided by volume. A 10 mg vial of either with 1 ml of diluent gives 10 mg per ml. Where BPC-157's 5 mg format is used, the same 1 ml gives 5 mg per ml instead — the only point at which the two diverge operationally.

Bacteriostatic water is the usual diluent for both where a vial will be entered more than once, its 0.9% benzyl alcohol content acting as the preservative that permits repeat entry. peptcalc.com converts vial mass and target concentration into the volume to add.

Neither carries a modification that changes handling. Unmodified linear peptides are comparatively forgiving in the dried state, though once in solution both are subject to the same aggregation and adsorption routes as anything else in the catalogue.

Both are short unmodified peptides, which makes their certificates simpler to read than those of engineered analogues. Identity is confirmed by mass spectrometry against the theoretical mass of the intended sequence, and for peptides this size a matching mass is close to unambiguous.

Purity is the HPLC main-peak area as a percentage of total peak area. For unmodified peptides the impurities that appear are typically deletion sequences — material missing a single residue where a coupling step failed — which elute close to the main peak and are visible on the attached chromatogram.

Peptide content, where reported separately, accounts for counter-ions and residual water. Both compounds are supplied as acetate salts, so the nominal vial mass overstates the mass of peptide present, and this figure is what reconciles the two.