N-(Mal-PEG6)-N-bis(PEG3-amine)

N-(Mal-PEG6)-N-bis(PEG3-amine), is designed to provide a hydrophilic, flexible polyethylene glycol (PEG)-based spacer that can improve solubility and mitigate non-specific interactions in targeted protein degradation constructs. Its functional architecture supports conjugation to protein-binding ligands and facilitates the formation of stable, well-defined PROTAC intermediates. The detailed Structure and Reactivity guidance below describes the chemical features and practical considerations for assembling PROTACs using this linker.

Structure: The linker comprises a maleimide-activated PEG segment connected to a bis(PEG3-amine) motif, yielding multiple ether-rich, conformationally flexible chains. It contains a maleimide electrophile suitable for selective adduct formation and primary amines for subsequent coupling. The overall composition confers high aqueous compatibility and reduced aggregation.

Reactivity: Maleimide groups typically undergo nucleophilic addition with thiols under mildly basic to neutral conditions, forming stable thioether linkages. The pendant primary amines enable amide-bond formation or other amine-directed conjugations using standard coupling chemistries, often requiring activation of carboxylic acids or electrophilic partners. Suitable solvents include aqueous buffers with compatible organic co-solvents, and reaction progress is commonly monitored by analytical methods such as LC-MS.