Thermo Scientific Pierce EZ-Link Phosphine-PEG3-Biotin is a biotinylation reagent for labeling azide-containing molecules, which enables biotin-based detection and affinity purification of molecules via Staudinger ligation strategies.

Features of EZ-Link Phosphine-PEG3-Biotin:

• Soluble—easily dissolves in water-miscible solvents (e.g., DMSO) for subsequent dilution in aqueous reaction mixtures with cell lysates and other biological samples
• Compatible—reaction chemistry occurs effectively in simple buffer conditions; requires no accessory reagents such as copper or reducing agents
• Chemoselective—the phosphine reactive group is specific in biological samples for bioorthogonal azide-tagged molecules, ensuring that biotinylation is specific
• PEG spacer—polyethylene glycol spacer arm helps maintain solubility of labeled molecules and decreases steric hindrance for affinity-binding to avidin, streptavidin or NeutrAvidin Protein

When used in combination with azide labeling strategies, this compound enables detection or affinity purification of protein interactions and post-translational modifications using streptavidin probes or streptavidin agarose resins. The phosphine group of Phosphine-PEG3-Biotin conjugates to azide groups by the Staudinger reaction mechanism. Azide groups can be introduced into proteins or other cellular targets through in vivo labeling with azide-tagged derivatives of naturally occurring metabolic building blocks. Because neither phosphines nor azides are present in biological systems, they comprise a chemoselective (mutually specific) ligation pair for labeling and conjugation.