DBCO-PEG9-amine

This DBCO-PEG9-amine linker is designed for efficient, bioorthogonal conjugation in targeted protein degradation workflows. It combines a strained cyclooctyne (DBCO) handle with a PEG-based spacer terminated by an amine, enabling robust coupling to biomolecular ligands and subsequent PROTAC assembly. Its flexible, hydrophilic architecture can help preserve binding and improve conjugation outcomes, while the DBCO moiety supports selective click-type ligations under mild conditions. Detailed structural and reactivity considerations are provided below.

Structure: The linker contains a DBCO cyclooctyne core for strain-promoted cycloaddition, connected to a poly(ethylene glycol) chain and a terminal primary amine. It features ether linkages within the PEG segment and a reactive strained alkyne within the DBCO unit, yielding a hydrophilic, water-compatible scaffold.

Reactivity: The DBCO functionality is suitable for strain-promoted azide–alkyne cycloaddition with azide-bearing partners, typically proceeding without copper catalysis. The terminal amine enables standard amide coupling or carbamate formation with activated carboxylic acids or activated carbonyl derivatives, often using coupling reagents and base in aqueous or mixed organic solvents. Reaction performance is generally optimized by maintaining neutral to mildly basic pH and minimizing nucleophilic side reactions.