This chemical is widely used in bioconjugation and protein labeling applications. Its maleimide group reacts specifically with thiol groups (-SH) in cysteine residues of proteins, enabling the formation of stable thioether bonds. The NHS ester moiety allows for efficient conjugation with primary amines (-NH2) present in lysine residues or at the N-terminus of proteins. The sulfonate group enhances water solubility, making it suitable for aqueous reaction conditions. It is commonly employed in the preparation of antibody-drug conjugates (ADCs), enzyme labeling, and immobilization of biomolecules on solid supports for diagnostic assays. Its dual reactivity makes it a versatile tool in the development of bioconjugates for therapeutic and research purposes.