AF™ 350 NHS Ester (Alexa Fluor® 350 NHS Ester equivalent) is an amine reactive, water-soluble blue emitting dye used to specifically and efficiently modify a primary amine (e.g., side chain of lysine residues or aminosilane-coated surfaces) at pH 7-9 to form a stable, covalent amide bond. The NHS ester (or succinimidyl ester) is the most popular tool for conjugating dyes to the primary amines of protein or antibody (Lys), amine-modified oligonucleotides, and other amine-containing molecules.
AF™ 350 is moderately photostable, blue-fluorescent probe optimally excited by the 350 nm laser line routinely used for generation of stable signal in imaging and flow cytometry. The brightness and photostability of blue dyes are best suited to direct imaging of high-abundance targets.