5-Carboxyfluorescein succinimidyl ester / 5-FAM-SE

5-Carboxyfluoresceinsuccinimidylester. Amine-reactive fluorescein dye marker for fluorescence labeling, especially for labeling of biomolecules (Abs: 495 nm, Em: 519 nm). This single isomer amine-reactive derivatization reagent may be used for covalent labeling of proteins and alkylamino modified nucleic acids. Fluorescein has an excitation maximum that closely matches the 488nm spectral line of the argon-ion laser, making it the predominant fluorophore for confocal laser scanning microscopy and flow cytometry applications. It has a relatively high absorptivity, excellent fluorescence quantum yield, and good water solubility. Importantly, protein-fluorescein conjugates are not inordinately susceptible to precipitation. The coupling reaction is usually carried out at pH 8-9.5.