Biotin-PEG3-Mal is a biotinylated polyethylene glycol (PEG) derivative used as a linker in the synthesis of proteolysis targeting chimeras (PROTACs). By introducing the biotin moiety, it enables specific recognition and binding to target proteins. Additionally, the PEG spacer contributes to improved solubility and flexibility of the linker. This compound offers a valuable tool for constructing PROTACs, which hold great potential in targeted protein degradation strategies[1].