Used in bioconjugation and pharmaceutical research, this compound serves as a bifunctional linker that combines a carboxylic acid group with a protected amine via a hydrophilic PEG3 spacer. The hydrochloric acid salt enhances solubility and stability during handling. It is commonly employed in the synthesis of peptide-based drugs, antibody-drug conjugates (ADCs), and targeted therapeutics where precise molecular spacing and water solubility are critical. The PEG3 segment reduces aggregation and improves pharmacokinetic properties by increasing circulation time in vivo. Additionally, it supports solid-phase synthesis and is compatible with standard coupling reagents in peptide chemistry.