Azide-PEG3-Desthiobiotin

Desthiobiotin-PEG3-Azide is a trifunctional chemical probe designed for the chemoselective labeling and affinity enrichment of alkyne-modified biomolecules. Its strategic design combines a terminal azide that forms a stable triazole adduct with alkyne-tagged molecules via bio-orthogonal click chemistry—either catalyzed by Copper(I) (CuAAC) or proceeding catalyst-free with strained alkynes (SPAAC)—a hydrophilic PEG3 spacer to enhance solubility, and a desthiobiotin affinity tag. The probe′s pivotal advantage is the reversible, high-affinity binding of desthiobiotin to streptavidin (Kd ≈ 10⁻¹¹ M), which permits gentle, competitive elution that preserves the integrity of captured proteins and their interaction partners. Consequently, it serves as a central reagent in chemical proteomics for the affinity pull-down, enrichment, and subsequent mass spectrometry-based identification of alkyne-labeled biomolecules from complex cellular lysates, proving indispensable where the recovery of viable protein complexes is critical.