DANSYL CHLORIDE (Derivatization Reagent) DR116   5-Dimethylaminonapthalene-1-sulfonyl chloride [ 605-65-2 ]   f.w.: 269.5 daltons

Dansyl Chloride is a reagent used for fluorescent labeling of proteins, N-terminal amino acids, peptides and amines. The reagent is soluble in DMF, acetone (50 mg/ml), chloroform, pyridine, benzene, and dioxane. Insoluble in water. Dansyl chloride is nonfluorescent until it reacts with amines. The resulting Dansyl amides have environmentally sensitive fluorescence quantum yields and emission maxima along with large Stokes shifts. Its fluorescence spectrum is greatly perturbed by the local environment. This environment-sensitive fluorescence property has made Dansyl chloride an important tool for biophysical studies. It is particularly useful for preparing fluorescent drug or ligand analogs that are expected to bind to hydrophobic sites in proteins or membranes. Dansyl protein conjugates have fluorescence lifetimes of 10–20 nanoseconds, and this feature potentially makes Dansyl dyes a good fluorescence polarization fluorophore. Dansyl chloride is widely used as a derivatization reagent for HPLC detection.