BPC-157: A Research Reference

BPC-157: A Research Reference

BPC-157 is among the most widely catalogued research peptides, and its composition makes it an instructive example of how sequence dictates analytical method. It is a pentadecapeptide — fifteen amino acid residues — with an unusual residue distribution that has direct consequences for how it must be detected, separated and quantified. This reference covers its chemical identity, structural features and verification.

The scope is chemistry and laboratory analysis. No use of any kind is described.

Chemical identity

BPC-157 carries CAS registry number 137525-51-0. Its molecular formula is C62H98N16O22, giving a molecular weight of approximately 1,419.54 g/mol. It is commonly catalogued under several orthographic variants — BPC-157, BPC 157 and BPC157 — which are the same compound differently punctuated rather than distinct materials.

The sequence is GEPPPGKPADDAGLV in single-letter notation: Gly-Glu-Pro-Pro-Pro-Gly-Lys-Pro-Ala-Asp-Asp-Ala-Gly-Leu-Val. At fifteen residues it sits in a convenient middle range for synthesis and analysis, large enough to be well retained on a reversed-phase column and small enough to give a clean, easily interpreted mass spectrum.

Reading the sequence

Three compositional features stand out, and each carries an analytical consequence.

Four proline residues. The sequence contains a run of three consecutive prolines followed by a fourth shortly after. Proline is conformationally distinctive: its side chain bonds back to its own backbone nitrogen, forming a ring that removes the amide hydrogen and severely restricts rotation. A peptide this proline-rich is conformationally constrained and tends toward extended rather than folded arrangements.

The practical analytical consequence is cis-trans isomerism. The bond preceding a proline can adopt either configuration, and where interconversion is slow relative to the chromatographic timescale this produces peak broadening or apparent peak splitting. With four prolines the effect is compounded. An analyst unfamiliar with the compound may read a broadened or shouldered peak as an impurity when it is a conformational artefact of the same molecule.

No aromatic residues. The sequence contains no tryptophan, no tyrosine and no phenylalanine. This removes the option of ultraviolet detection at 280 nm entirely, since there is no chromophore to absorb there. Detection must rely on the peptide bond itself absorbing near 214 nm — a workable approach, but one that constrains the choice of solvents and buffers, since many common mobile-phase components absorb strongly in that region.

Two adjacent aspartate residues. Aspartate participates in a well-characterised degradation route in which its side chain attacks the adjacent peptide backbone to form a cyclic succinimide intermediate, which can then reopen to give a rearranged isoaspartate product. The rearranged form has the same mass as the original, which means mass spectrometry alone cannot detect it. Chromatographic separation is required, since the two forms differ in retention.

Synthesis considerations

Fifteen residues require fourteen coupling steps. Proline-rich sequences are known to be more difficult to assemble than average, because the constrained ring structure reduces the accessibility of the amine group for the next coupling. Consecutive prolines compound the difficulty, and incomplete coupling at these positions is a recognised source of deletion sequences.

The resulting impurity profile therefore tends to cluster around specific positions rather than being randomly distributed. A deletion of one proline from a run of three produces a peptide 97 g/mol lighter, which is readily detected by mass spectrometry against the theoretical 1,419.54.

Analytical verification

Research-grade BPC-157 is typically specified at greater than 98% purity by HPLC with identity confirmed by LC-MS. Given the compositional features above, several elements of a Certificate of Analysis carry more weight than the headline number.

• The detection wavelength, which for this compound must be in the low ultraviolet region rather than 280 nm.
• Whether the method resolves isoaspartate-rearranged material, which is mass-invisible.
• The observed mass against the theoretical 1,419.54 g/mol.
• A batch identifier that can be matched to the vial.

Physical form and storage chemistry

BPC-157 is supplied as a lyophilised powder, white to off-white, in a sealed glass research vial. The dried state suppresses hydrolysis, which requires water, and slows the aspartate rearrangement pathway by limiting molecular mobility.

The absence of methionine, cysteine and tryptophan means oxidation is a comparatively minor concern for this compound — a useful contrast with sequences such as MOTS-C, where oxidation-susceptible residues dominate the stability picture. For BPC-157 the aspartate chemistry and moisture exclusion are the relevant considerations.

Nomenclature and identification

BPC-157 appears in catalogues and literature under several orthographic forms — BPC-157, BPC 157, BPC157 — which differ only in punctuation. These are not distinct materials, and the variation is a formatting convention rather than a chemical one.

As with any research peptide, the reliable identifiers are the CAS number and the molecular formula rather than the written name. For this compound the sequence itself is also a complete structural description at fifteen residues, which is short enough to publish in full on a specification. Where a supplier states CAS 137525-51-0, formula C62H98N16O22 and sequence GEPPPGKPADDAGLV together, identification is unambiguous.

One caveat applies to sequence notation generally: it specifies composition and order but not terminal groups or stereochemistry. Two materials both correctly described as GEPPPGKPADDAGLV could differ in whether the C-terminus is a free acid or an amide, and that difference would appear as roughly one mass unit on a spectrum.

Situating the compound

Comparing BPC-157 against other peptides in a research catalogue is a useful way to understand what its specification should contain. At 1,419.54 g/mol it is roughly twice the mass of Ipamorelin and around a third that of TB-500, placing it in a comfortable middle range where synthesis is tractable and analysis is uncomplicated by the resolution demands that large peptides impose.

Where it is unusual is composition rather than size. Its proline density is high, and the complete absence of aromatic residues puts it in the same detection-constrained category as Selank and the short bioregulators, despite being considerably larger than either. A method developed for an aromatic-containing peptide of similar mass would not transfer to it without adjustment.

Corix Labs supplies BPC-157 5mg and BPC-157 10mg as lyophilised research preparations, and as a component of a blended vial with TB-500 and a twin vial pack.

Corix Labs publishes analytical documentation for its research materials. See third-party testing reports for further detail on how batches are verified.

All materials referenced in this article are supplied strictly for laboratory research and analytical use. They are not licensed medicines and are not sold for use in humans or animals. Nothing in this article constitutes guidance on administration, preparation for use, or any clinical, therapeutic, diagnostic or cosmetic application.