DBCO-PEG12-NHS ester

Dibenzocyclooctyne (DBCO)–PEG-based NHS ester is a bifunctional PROTAC linker designed to couple a cyclooctyne handle to primary amine–containing ligands under mild, bioconjugation-compatible conditions. Its PEG spacer improves aqueous solubility and reduces steric constraints between the targeting moieties, supporting efficient formation of the productive ternary complex required for targeted protein degradation. The following points describe the linker’s structure and practical reactivity for PROTAC construction in detail below.

Structure: The molecule combines a DBCO cyclooctyne core with a polyethylene glycol spacer and a terminal N-hydroxysuccinimide ester. It contains an activated ester for nucleophilic acyl substitution and a strained alkyne suitable for copper-free cycloaddition. The PEG segment provides flexible, hydrophilic character and favorable dispersion in aqueous media.

Reactivity: The NHS ester reacts with primary amines to form stable amide bonds via nucleophilic acyl substitution, typically using buffered aqueous conditions that preserve ligand integrity. The DBCO group undergoes strain-promoted azide–alkyne cycloaddition with azide-bearing partners without copper catalysis, enabling orthogonal conjugation. Common solvents include aqueous buffers with compatible co-solvents when needed; reaction monitoring by analytical methods is recommended to control coupling efficiency and minimize hydrolysis.