XFD555 azide

• Ex/Em: 553/568 nm
• Extinction coefficient: 155,000 cm^-1M^-1
• Reactive Group: Azide
• Click Chemistry Conjugation: Efficiently and rapidly labels terminal alkynes via CuAAC and copper-free SPAAC
• Bright & Stable: Exhibits intense fluorescence with resilience to photobleaching and pH variations from 4 to 10
• Hydrophilic: Minimizes aggregation, enhancing signal clarity for advanced imaging and live-cell studies

XFD555, manufactured by AAT Bioquest, is structurally identical to Alexa Fluor™ 555 (ThermoFisher). It is a bright orange-fluorescent dye with an excitation optimized for use with either the 488 nm line of the argon-ion laser or the 532 nm line of the frequency-doubled Nd:YAG laser. The high fluorescence quantum yield and high photostability of XFD555 allow for the detection of low-abundance biological structures with great sensitivity. XFD555 demonstrates good aqueous solubility and pH-insensitivity over a broad pH range (pH 4–10), ensuring stable fluorescence generation under varying experimental conditions. XFD555 dye molecules can be attached to proteins at high molar ratios without significant self-quenching, enabling brighter conjugates and more sensitive detection in imaging and flow cytometry.

The azide derivative of XFD555 is widely used for labeling terminal alkynes on peptides, antibodies, and other biomolecules via click chemistry. It participates in copper-catalyzed azide-alkyne cycloaddition (CuAAC) with alkyne-containing molecules and strain-promoted alkyne-azide cycloaddition (SPAAC) with DBCO- or BCN-containing molecules.