Aladdin™ 350 is a blue-fluorescent dye. Used for stable signal generation in imaging and flow cytometry, Aladdin™ 350 dye is water soluble and pH-insensitive from pH 4 to pH 10. In addition to reactive dye formulations, we offer Aladdin™ 350 dye conjugated to a variety of antibodies, peptides, proteins, tracers, and amplification substrates optimized for cellular labeling and detection. The NHS ester (or succinimidyl ester) of Aladdin™ 350 is the most popular tool for conjugating this dye to a protein or antibody. NHS esters can be used to label to the primary amines (R-NH2) of proteins, amine-modified oligonucleotides, and other amine-containing molecules. The resulting Aladdin™ conjugate will exhibit brighter fluorescence and greater photostability than the conjugates of other spectrally similar fluorophores. Detailed information about this Aladdin™ NHS ester: Fluorophore label: Aladdin™ 350 dye Reactive group: NHS ester Reactivity: Primary amines on proteins and ligands, amine-modified oligonucleotides Ex/Em of the conjugate: 346/445 nm Extinction coefficient: 19,000 cm-1M-1 Spectrally similar dyes: Marina Blue Molecular weight: 410.35 Typical Conjugation Reaction You can conjugate amine-reactive reagents with virtually any protein or peptide (the provided protocol is optimized for IgG antibodies). You can scale the reaction for any amount of protein, but the concentration of the protein should be at least 2 mg/mL for optimal results. We recommend trying three different degrees of labeling, using three different molar ratios of the reactive reagent to protein. Aladdin™ NHS ester is typically dissolved in high-quality anhydrous dimethylformamide (DMF) or dimethylsulfoxide (DMSO), and the reaction is carried out in 0.1–0.2 M sodium bicarbonate buffer, pH 8.3, at room temperature for 1 hour. Because the pKa of the terminal amine is lower than that of the lysine epsilon-amino group, you may achieve more selective labeling of the amine terminus using a buffer closer to neutral pH.