Peptide nomenclature and how to read a product name

Three naming systems in parallel

Research peptides usually carry three names at once: a systematic chemical description, a development code assigned by whoever first synthesised the molecule, and sometimes a non-proprietary generic name. BPC-157, for instance, is a development code; the systematic description is a fifteen-residue partial sequence of body protection compound.

Development codes follow no universal convention. GHRP-2 and GHRP-6 are numbered by order within a series; TB-500 references thymosin beta but is not the full protein; CJC-1295 is a company internal designation. The code alone tells you very little, which is why the sequence and mass on the certificate of analysis are the authoritative identifiers.

Fragment notation

Parenthetical ranges indicate which residues of a parent molecule are present. GHRH(1-29) is the first twenty-nine residues of growth hormone-releasing hormone. hGH(176-191) is an internal fragment of human growth hormone. When a fragment is described as retaining full activity, it means the receptor-binding determinants happen to lie within that range.

Suffixes that change the molecule

A suffix frequently marks a genuinely different compound rather than a variation in presentation. DAC denotes a drug affinity complex — a covalent albumin-binding linker that extends half-life from minutes to days. Modified in a name usually signals amino-acid substitutions made for protease resistance. PEG- indicates polyethylene glycol conjugation. LR3 on IGF-1 denotes both an N-terminal extension and a position-3 substitution.

The practical rule: if a suffix changes the molecular formula, it is a separate compound and deserves a separate specification, certificate and product record. If it changes only the quantity in the vial, it is a strength variant of the same compound.

Salt form and net peptide content

Synthetic peptides are usually isolated as trifluoroacetate or acetate salts, and the counter-ion contributes mass. A vial labelled 5 mg may therefore contain somewhat less than 5 mg of peptide by net content. Certificates that report net peptide content alongside gross weight remove this ambiguity, which matters whenever molar concentration is being calculated.