TCO-PEG4-acid

TCO-PEG4-acid is a bifunctional PROTAC linker designed to connect targeting ligands through a polyethylene glycol spacer while providing a carboxylic acid handle for controlled conjugation. Its PEG-based segment supports favorable solubility and conformational flexibility, which can improve productive ternary complex formation in targeted protein degradation workflows. The following sections describe the linker’s structure and the practical reactivity considerations relevant to PROTAC assembly.

Structure: The linker comprises a terminal carboxylic acid attached to a PEG4 ethylene glycol chain, providing a hydrophilic, flexible spacer. It contains ether linkages within the PEG segment and a terminal acid functionality suitable for amide or ester formation. Overall, it is designed for aqueous compatibility and controlled linker length.

Reactivity: The carboxylic acid group is typically activated for coupling to amine-bearing ligands, commonly via carbodiimide-mediated amide bond formation or related activation chemistries. Reaction conditions are generally selected to preserve sensitive functional groups on the partner ligands and to maintain solubility of both components. Mild bases and polar organic solvents are commonly used to drive coupling while minimizing side reactions, enabling efficient PROTAC construction through stable covalent linkage.