Peptide Modifications
Many research peptides are not bare sequences: they carry chemical modifications that change stability, solubility, or behavior in analytical work. These are the modifications you will most often see in catalog names.
Last updated September 2, 2026
Terminal modifications
The two ends of a peptide chain are its most common modification sites. N-terminal acetylation caps the free amine; C-terminal amidation converts the carboxyl to an amide. Both changes remove a charge present in the unmodified chain, which alters solubility and makes the peptide more resistant to exopeptidase degradation in in-vitro systems.
PEGylation and conjugation
PEGylation attaches polyethylene-glycol chains to the peptide, increasing its hydrodynamic size and aqueous solubility. Conjugation more broadly covers attachment of other groups — fluorescent dyes for imaging assays, biotin for pull-down and binding experiments, or fatty-acid chains that change how the molecule partitions in solution.
Cyclization
Linear peptides are conformationally flexible. Cyclization — head-to-tail, side-chain-to-side-chain, or through a disulfide bridge between two cysteines — locks part of that flexibility, producing a more rigid molecule that is generally more stable against enzymatic breakdown and often more selective in binding assays.
Why it matters when ordering
A modified peptide is a different molecule from its unmodified parent: different mass, different chromatographic behavior, different stability profile. Always match the exact modification state on the label and COA to the sequence your work calls for — the nomenclature guide covers how these appear in catalog names.
RESEARCH USE ONLY — NOT FOR HUMAN CONSUMPTION. Products are laboratory reagents for in-vitro research by qualified professionals. Sale for human use is strictly prohibited. Nothing in this guide is medical advice or dosing guidance.