What is Sequence? (Peptide Glossary)

A peptide's sequence is its identity: the exact order of amino acids, written by convention from the N-terminus (amino end) to the C-terminus (carboxyl end). BPC-157's sequence - Gly-Glu-Pro-Pro-Pro-Gly-Lys-Pro-Ala-Asp-Asp-Ala-Gly-Leu-Val - defines it completely. Change one amino acid and you have a different molecule with potentially different activity.

Sequences matter practically when comparing vendors. Some suppliers sell analogs or fragments under familiar names - TB-500 is a fragment of thymosin beta-4, not the full protein, and CJC-1295 exists in DAC and no-DAC versions with different sequences and different molecular weights. The COA should confirm the exact sequence variant being sold via mass spectrometry.

Sequence also determines synthesis difficulty and therefore price. Short sequences like KPV (3 amino acids) are cheap and reliable to make. Long or modified sequences like tirzepatide (39 amino acids plus a fatty acid side chain) are expensive, failure-prone syntheses - which is why suspiciously cheap complex peptides are a classic counterfeit indicator.