NH2-PEG3-C1-Boc is a PEG-based PROTAC linker that is applicable to the synthesis of PROTACs. Application： Applicated in medical research, drug-release, nanotechnology and new materials research, cell culture. In the study of ligand, polypeptide synthesis support, a graft polymer compounds, new materials, and polyethylene glycol-modified functional coatings and other aspects of the active compound. Monodisperse Amino-PEG3-CH2CO2-t-butyl ester (NH2-PEG3-CH2COOtBu) is a heterobifunctional PEG molecule containing an amino (NH2) group with a t-butyl protected carboxyl group. The hydrophilic PEG spacer increases solubility in aqueous media. The amino group is reactive with carboxylic acids, activated NHS esters, carbonyls (ketone, aldehyde) etc. The t-butyl protected carboxyl group (t-Boc) can be deprotected under acidic conditions. NH2-PEG3-CH2COOtBu also known as PROTAC Linker 5, can be used as a PROTAC linker, which refers to the alkyl/ether composition.