Used in bioconjugation for labeling and crosslinking biomolecules. The alkyne group enables click chemistry, particularly copper-catalyzed azide-alkyne cycloaddition (CuAAC), allowing selective attachment to azide-containing molecules. The NHS ester reacts efficiently with primary amines on proteins, peptides, or amine-modified nucleic acids, forming stable amide bonds. Commonly used in proteomics, drug discovery, and development of fluorescent probes or biotinylated molecules for detection and affinity purification. Ideal for introducing alkyne handles into biomolecules for downstream conjugation via click reactions.