Biotin-PEG2-azide

Biotin-PEG2-azide is a PEG-based, biotin-bearing chemical linker designed for modular PROTAC construction, enabling efficient conjugation of targeting ligands to E3-recruiting or affinity handles. Its azide functionality supports bioorthogonal coupling strategies, while the PEG spacer promotes favorable solubility and linker flexibility, which can improve conjugate handling and reduce steric constraints during ternary complex formation. The

Structure: This linker contains a biotin moiety connected through a short polyethylene glycol spacer to a terminal azide group. The structure features amide and ether linkages within the PEG chain, along with an azide functional group suitable for click-type transformations. Overall, it is a polar, water-compatible scaffold with flexible connectivity.

Reactivity: The terminal azide enables copper-free or copper-catalyzed azide–alkyne cycloaddition with appropriately functionalized partners, commonly using strained alkynes for rapid kinetics. Typical conditions employ compatible aqueous or mixed solvent systems, with catalyst choice (and ligand additives when applicable) tailored to preserve sensitive biomolecule conjugates. Mechanistically, cycloaddition proceeds via formation of a triazole linkage, facilitating stable PROTAC assembly under mild, bioorthogonal-compatible conditions.