m-PEG24-acid

m-PEG24-acid is a polyethylene glycol-based linker acid designed for constructing PROTACs and other bifunctional degraders that require a flexible, water-compatible spacer between binding motifs. Its PEG-rich architecture supports solubility and can reduce steric constraints during ternary-complex formation, improving practical conjugation workflows. The sections below describe the linker’s structural features and provide guidance on suitable synthetic strategies for PROTAC assembly.

Structure: m-PEG24-acid comprises a polyethylene glycol chain terminating in a carboxylic acid, with ether linkages that confer conformational flexibility. The acid functionality enables stable amide formation, while the PEG segment provides hydrophilicity and reduced aggregation. Overall, the linker behaves as a polar, bioconjugation-ready spacer.

Reactivity: The carboxylic acid can be activated for coupling to amine-bearing ligands via standard amide-forming chemistries, typically using carbodiimide coupling systems with an appropriate base and an anhydrous polar solvent. Alternatively, acid activation followed by nucleophilic acyl substitution enables controlled attachment while preserving PEG integrity. Reaction design should consider maintaining mild conditions to minimize side reactions and ensure efficient PROTAC conjugation.