Brightly fluorescent purple and blue labels for amines and proteins.

Novel amino-reactive phenoxazines were obtained by reasonably simple synthetic protocols and characterized in terms of their use as fluorescent labels for amines, amino acids and proteins in general. Purple labels (alternatives to Texas Red) and blue labels (alternatives to Cy-1) were obtained by this strategy. The absorption/emission maxima, in aqueous solution, are at around 589/630 nm and 648/670 nm, respectively, thus indicating larger Stokes' shifts than those of common cyanine-type of labels. The new labels are compatible with commercial diode laser light sources.