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.

• Easily Dissolves in Water-Miscible Solvents (eg. DMSO) for Subsequent Dilution in Aqueous Reaction Mixtures with Cell Lysates and Other Biological Samples
• Reaction Chemistry Occurs Effectively in Simple Buffer Conditions; Requires no Accessory Reagents, Such as Copper or Reducing Agents
• Phosphine Reactive Group is Specific in Biological Samples for Bioorthogonal Azide-Tagged Molecules, Ensuring that Biotinylation is Specific
• PEG 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 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.