Azido-PEG4-acetic Acid

Azido-PEG4-acetic Acid is a PEG-based linker bearing a terminal azide and a carboxylic acid handle, enabling modular assembly of PROTACs through widely used bioorthogonal and amide-forming chemistries. Its flexible polyethylene glycol segment supports productive spatial presentation of ligands, while the azide provides a versatile attachment point for conjugation strategies. Researchers can use it to build targeted protein degradation constructs, with the following sections describing its structure and practical reactivity considerations in detail below.

Structure: The molecule comprises a polyethylene glycol chain terminated by an azide functional group and an acetic acid moiety. It contains ether linkages within the PEG backbone, a carboxylic acid for hydrogen bonding and salt formation, and an azide suitable for click-type transformations.

Reactivity: The azide group is compatible with copper-catalyzed azide–alkyne cycloaddition and related azide-based conjugation approaches, typically requiring an alkyne partner under conditions that preserve sensitive biomolecular ligands. The carboxylic acid can be activated for amide bond formation using standard coupling chemistries (for example, carbodiimide-based systems with additives) in polar aprotic solvents, enabling attachment to amine-bearing ligands used in PROTAC architectures.