Used in bioconjugation processes to link proteins, peptides, or other biomolecules through thiol and amine groups. The acetylthio group acts as a protected thiol, which can be deprotected to release a reactive thiol for forming disulfide bonds. The NHS ester reacts efficiently with primary amines on biomolecules to form stable amide bonds. Commonly employed in the preparation of antibody-drug conjugates, protein labeling with fluorescent dyes or biotin, and immobilization of biomolecules on surfaces such as biosensors or microarrays. Its crosslinking ability makes it valuable in pharmaceutical research and diagnostic development.