Amino-PEG12-propionic acid

Amino-PEG12-propionic acid is a PEG-based, bifunctional linker building block designed for constructing PROTACs and related targeted protein degradation conjugates. Its hydrophilic, flexible polyethylene glycol segment helps tune solubility and spatial presentation of functional groups, while the amino and carboxylic acid handles enable robust coupling to ligands. The following sections describe its structure and the practical reactivity considerations for PROTAC assembly.

Structure: The linker comprises a polyethylene glycol chain terminated with an amino group and a propionic-acid-derived carboxyl functionality. It contains ether linkages characteristic of PEG, along with amine and carboxylic acid functional groups. Overall, it is flexible, polar, and typically exhibits good water compatibility, supporting stable conjugation chemistry.

Reactivity: The primary amino and carboxylic acid groups support standard amide or carbamate-forming coupling strategies used in PROTAC synthesis. Typical approaches include activating the carboxylic acid with common coupling reagents (often in the presence of base) to react with amines, or converting the acid to an activated ester for nucleophilic substitution. Mild, anhydrous conditions are generally employed to minimize side reactions, with polar organic solvents such as DMF or DMSO frequently used.