Azido-PEG23-amine

Azido-PEG23-amine is a PEG-based bifunctional linker designed for modular PROTAC assembly, enabling efficient conjugation between a ligand bearing an amine handle and a partner that can be functionalized for attachment. Its flexible ethylene glycol backbone supports productive spatial presentation and can improve solubility and linker-mediated dynamics in targeted protein degradation constructs. The sections below describe its structure and practical reactivity considerations in PROTAC linker chemistry.

Structure: Azido-PEG-amine contains a terminal azide group and a terminal primary amine separated by a poly(ethylene glycol) chain. The molecule features flexible ether linkages along the PEG backbone, with an azide substituent and an amine functionality that provide orthogonal reactive handles for sequential bioconjugation.

Reactivity: The azide group is commonly used in copper-catalyzed azide–alkyne cycloaddition or related strain-promoted click strategies, enabling attachment to alkyne-bearing ligands under mild conditions. The primary amine can be coupled via standard amide or urea-forming chemistries (e.g., activated carboxylic acids or isocyanate-derived reagents). Orthogonal use of azide and amine supports stepwise PROTAC synthesis, typically using polar organic solvents and aqueous-compatible buffers while minimizing conditions that degrade PEG or azide functionality.