Mal-amido-PEG6-acid

Mal-amido-PEG6-acid is a polyethylene glycol-based PROTAC linker designed to connect a ligand for an E3 ligase to a target-binding moiety while providing conformational flexibility and improved solubility. Its amide functionality enables robust conjugation strategies commonly used in targeted protein degradation workflows. The linker’s hydrophilic PEG segment can help tune linker length and reduce aggregation, supporting efficient formation of degraders. Detailed structural and reactivity considerations are provided below.

Structure: Mal-amido-PEG6-acid features a PEG chain terminating in a carboxylic acid and an amide-linked maleimide motif. The conjugation-ready maleimide provides a Michael acceptor for thiol capture, while the PEG segment contributes hydrophilicity and flexible ether linkages. Overall, it is a polar, water-compatible linker suitable for bioconjugation.

Reactivity: The maleimide group undergoes thiol–maleimide Michael addition under mildly basic conditions, forming a stable thioether linkage that is widely used for PROTAC assembly. Suitable thiol-containing partners are typically generated from cysteine residues or thiol-bearing intermediates. Reactions are commonly performed in aqueous or mixed aqueous buffers with controlled pH to favor selective addition while minimizing maleimide hydrolysis; purification by standard chromatographic or precipitation methods is often used to remove unreacted components.