Used in bioconjugation and bioorthogonal chemistry for labeling and detecting biomolecules. The alkyne group enables click chemistry reactions, such as copper-catalyzed azide-alkyne cycloaddition (CuAAC), allowing selective attachment to azide-modified molecules like proteins, nucleic acids, or cell surfaces. The PEG4 spacer enhances solubility and reduces steric hindrance, improving reaction efficiency. Desthiobiotin provides a reversible biotin analog for affinity purification, enabling gentle elution of captured targets using biotin competition. Commonly applied in proteomics, live-cell imaging, and target identification workflows where reversible, specific, and efficient conjugation is required.