Bis-PEG5-acetic acid

Bis-PEG5-acetic acid is a bifunctional polyethylene glycol-based linker designed for assembling PROTAC constructs that require controlled spacing and enhanced solubility. Its two carboxylic acid termini enable robust conjugation to complementary PROTAC warhead and E3 ligase-binding components, supporting efficient formation of targeted protein degraders. The flexible PEG scaffold can help reduce steric mismatch and improve aqueous handling, and the details below describe its structure and practical reactivity considerations.

Structure: Bis-PEG5-acetic acid is a PEG-derived, flexible bifunctional linker bearing two terminal acetic acid–type carboxylic acid groups. The structure contains repeating ether linkages that confer conformational mobility, hydrogen-bonding capacity, and strong hydrophilicity. Its functional groups support ester or amide formation under standard coupling chemistries.

Reactivity: The carboxylic acids are suitable for PROTAC linker installation via amide or ester bond formation using standard peptide-coupling or carboxyl activation approaches. Common strategies include activating the acid with coupling reagents (often in the presence of base) to form an intermediate that reacts with an amine or alcohol on the partner ligand. Mild, water-compatible solvents or mixed organic systems are typically used to maintain PEG solubility and minimize hydrolysis.