m-PEG3-aldehyde is a PEG-based linker for PROTACs which joins two essential ligands, crucial for forming PROTAC molecules. This linker enables selective protein degradation by leveraging the ubiquitin-proteasome system within cells.

PROTACs contain two different ligands connected by a linker; one is a ligand for an E3 ubiquitin ligase and the other is for the target protein. PROTACs exploit the intracellular ubiquitin-proteasome system to selectively degrade target proteins[1]. The binding affinities of anti-mPEGs depend more on the backbone lengths of the polymers and the hydrophobicities of their end-groups than on their resemblance to the methoxy terminus of the immunogenic polymer[1]. Aldehyde is reactive to hydrazide and aminooxy groups which are commonly used in biomolecular probes for labeling and crosslinking carbonyls (oxidized carbohydrates). The hydrophilic PEG spacer increases solubility in aqueous media.