Mal-PEG3-OH

Mal-PEG3-OH is a maleimide-terminated polyethylene glycol linker designed for efficient conjugation in PROTAC assembly workflows. Its maleimide functionality enables selective coupling to thiol-containing ligands, while the PEG spacer supports favorable solubility and flexible linker presentation to improve bioconjugation performance. The product is particularly useful for constructing targeted protein degraders where controlled attachment chemistry is required; detailed structural and reactivity considerations are provided below.

Structure: Mal-PEG3-OH comprises a maleimide electrophile linked to a short PEG chain ending in a terminal hydroxyl group. It contains a cyclic imide with activated alkene functionality and ether-rich PEG segments, providing conformational flexibility, improved hydrophilicity, and compatibility with aqueous bioconjugation conditions.

Reactivity: The maleimide group undergoes thiol–maleimide Michael addition under mildly basic aqueous conditions, typically using thiol-containing partners such as cysteine residues or thiol-functionalized ligands. Reactions are commonly performed in buffered aqueous solvents with controlled pH to favor selective addition while minimizing competing hydrolysis or side reactions. No special catalysts are generally required; careful stoichiometry and thiol protection/handling are important to maintain reactivity and reproducibility.