Mal-PEG4-alcohol

Mal-PEG4-alcohol is a PEG-based, maleimide-functional linker designed for efficient conjugation in targeted protein degradation workflows. Its maleimide handle enables selective coupling to thiol-bearing ligands, while the PEG spacer promotes solubility and favorable linker flexibility in PROTAC architectures. This product is commonly used to assemble degraders by connecting a thiol-reactive warhead to a partner ligand through a stable thioether linkage. The following points describe the structure and reactivity characteristics in detail.

Structure: The linker combines a maleimide electrophile with a polyethylene glycol chain terminating in an alcohol. It contains an alkene within the maleimide ring and ether linkages along the PEG segment, providing a polar, flexible scaffold that supports aqueous compatibility and controlled spatial presentation of attached ligands.

Reactivity: Maleimide groups undergo thiol–maleimide Michael-type addition to form a thioether, typically under mildly basic conditions that favor thiolate formation while minimizing maleimide hydrolysis. Suitable thiol sources include cysteine-containing ligands or reduced thiol reagents. Reactions are commonly performed in aqueous or mixed aqueous/organic solvents, with careful control of pH and temperature to preserve maleimide reactivity and maintain linker integrity during PROTAC synthesis.