Choose an appropriate reagent for metabolic labeling and chemoselective ligation.

Thermo Scientific™ Azide and Phosphine Reagents are chemical or metabolic labeling reagents for in vivo or in vitro chemoselective ligation of proteins and post-translational modification moieties. The azide-phosphine crosslinking strategy is called Staudinger ligation and makes possible a variety of specific detection, tagging and affinity purification approaches for studying cellular responses and pathways.

Featured data and reactions


Figure 1. Staudinger chemoselective ligation as a strategy for metabolic labeling. Phosphine-activated reagents (e.g., fluorescent dyes) will specifically conjugate to azide-labeled biomolecules to allow specific detection, purification and measurement.


Figure 2. Detection of metabolically incorporated azido-mannosamine with Thermo Scientific DyLight 650-Phosphine. HK-2 cells were incubated with N-azido-acetyl-mannosamine and the live cells were probed with azide-reactive DyLight 650-Phosphine (blue). Nuclei were counterstained with Hoechst33342 (red).

Highlights, features, and benefits

  • Easy-to-use—two-component reaction with no additional accessory reagents required
  • Chemoselective—specific reactivity of azide and phosphine minimizes off-target effects and produces very low background
  • Bioorthogonal—azido sugars are naturally incorporated without affecting biological activity
  • Copper-free—unlike other chemoselective ligation chemistries, Staudinger ligation is non-toxic to live cells and does not oxidize amino acid side chains or post-translational modifications
Features Benefits
Chemoselective reactivity
  • Virtually no side reactions with other functional groups
  • Detect and enrich while minimizing contamination
  • Enables accurate and representative biological observations
Compatible with bioorthogonal metabolic labeling
  • Terminal azido functional groups not found in living systems
  • Azido derivatives of biological molecules are well tolerated
High reaction efficiency
  • Up to 100% reaction efficiency in chemical model systems
Ease of use
  • Two-reagent system is easier to use and troubleshoot than alternative copper-catalyzed click chemistry (5 different reagents)
Biological-sample compatiibility
  • Reactions occur in aqueous solutions at physiological pH with no known side reactions with buffers/detergents
  • No risk for toxicity and protein oxidation because of the absence of Cu(I)
Allows probe switching
  • Azido-labeled molecules can be derivatized with wide variety of phosphine probes

Quick-link table of products

  Azide (N3) products Phosphine (P3) products
Reagents for chemical activation and conjugation: Crosslinking
Reagents for metabolic labeling and detection: Labeling