The red-fluorescent TAMRA azide can be reacted with terminal alkynes via a copper-catalyzed click reaction (CuAAC). It also reacts with strained cyclooctyne via a copper-free “click chemistry” reaction to form a stable triazole and does not require Cu-catalyst or elevated temperatures. TAMRA (tetramethylrhodamine) is a bright fluorescent label is compatible with various excitation sources including mercury arc, tungsten and xenon arc lamps, the 544 nm line of the Helium-Neon laser and the 532 nm green laser line.