Used in bioconjugation and protein modification, this reagent enables site-specific attachment of functional groups to biomolecules. Its Fmoc-protected amine ensures controlled deprotection in mild basic conditions, allowing sequential conjugation strategies in peptide synthesis. The NHS ester reacts efficiently with primary amines on proteins or peptides, forming stable amide bonds. The disulfide linker (SS) provides a cleavable bridge under reducing conditions, useful in drug delivery systems where intracellular release is desired. Commonly applied in the development of antibody-drug conjugates (ADCs), targeted therapies, and reversible immobilization of biomolecules on surfaces for assays or biosensors.