Mal-amido-PEG4-TFP ester

Mal-amido-PEG4-TFP ester, is designed to enable efficient conjugation between amine-bearing ligands and thiol-containing or maleimide-reactive partners within targeted protein degradation workflows. Its PEG-based spacer promotes favorable solubility and conformational flexibility, while the TFP ester provides a reactive acylating handle for forming stable amide linkages. The subsequent points describe the structural features and practical reactivity considerations for constructing PROTAC architectures.

Structure: The linker comprises a PEG spacer connected to a maleimide-derived amide motif and a TFP ester functional group. It contains ether linkages characteristic of PEG, an amide bond within the conjugation scaffold, and an activated carboxylate ester suitable for nucleophilic acyl substitution.

Reactivity: The TFP ester reacts with primary amines via acyl substitution to form amide bonds under mildly basic aqueous or mixed solvent conditions. Maleimide functionalities typically undergo selective thiol–maleimide addition through Michael-type chemistry, favoring rapid coupling to cysteine-containing ligands. Standard coupling workflows use freshly prepared linker solutions, controlled pH buffering, and compatible solvents such as aqueous buffers with organic cosolvents; catalysts are generally unnecessary for TFP-mediated amide formation.