This compound is widely used in bioconjugation and chemical biology for linking biomolecules, such as proteins, peptides, or antibodies, to other entities like dyes, drugs, or solid supports. Its maleimide group reacts selectively with thiol groups (-SH) in cysteine residues, enabling stable covalent bonding. The PEG4 spacer enhances solubility and reduces steric hindrance, improving the efficiency of conjugation. The pentafluorophenyl (PFP) ester group is highly reactive with amines, allowing for efficient coupling to amine-containing molecules. This makes it valuable in drug delivery systems, diagnostic assays, and the development of targeted therapies, where precise and stable molecular linkages are essential.