This compound, featuring a Dde protecting group, biotin moiety, PEG4 spacer, and terminal alkyne, is widely used in bioconjugation and chemical biology research, particularly for labeling biomolecules such as proteins, peptides, and nucleic acids. The alkyne group enables efficient click chemistry reactions, such as copper-free or catalyzed azide-alkyne cycloaddition, allowing the attachment of various probes, tags, or functional groups. The biotin component provides strong and specific binding to streptavidin or avidin, supporting applications in affinity purification, detection, imaging, immunoprecipitation, and pull-down assays. The PEG4 spacer improves aqueous solubility and minimizes steric hindrance, enhancing conjugation efficiency. The Dde group serves as an orthogonal protecting group for the amine, which can be selectively deprotected under mild acidic conditions (e.g., with hydrazine), facilitating stepwise molecular synthesis and modifications. It is commonly utilized in proteomics, drug discovery, and diagnostic assays to investigate molecular interactions, track biomolecules, or isolate targets.