Mal-amido-PEG9-amine

Mal-amido-PEG9-amine is a polyethylene glycol (PEG)-based linker designed for constructing PROTACs via stable amide coupling and subsequent conjugation to targeting ligands. Its flexible, hydrophilic PEG scaffold can enhance solubility and provide spatial separation between the binding elements, supporting efficient ternary complex formation in targeted protein degradation workflows.

Structure: The linker contains a PEG chain bearing terminal amine functionality and a mal-amido linkage, incorporating an amide bond that provides defined connectivity and conformational stability. Its ether-rich PEG segment contributes hydrophilicity and flexibility, while the amine enables further derivatization. Overall, it behaves as a bifunctional, water-compatible scaffold.

Reactivity: For PROTAC assembly, the terminal amine is commonly used for amide bond formation with activated carboxylic acids or carboxylate derivatives under standard peptide-coupling conditions. Mal-amido motifs support robust coupling chemistry consistent with amide-forming mechanisms. Typical approaches employ coupling reagents and base in polar aprotic solvents, followed by purification to remove excess reagents and byproducts, ensuring functional group integrity for downstream conjugation.