Our streptavidin, Pacific Blue™ conjugate is a bright, blue-fluorescent probe with excitation/emission ∼410/455 nm. Streptavidin is a nonglycosylated biotin-binding protein that is isolated from bacteria and has a near-neutral isoelectric point. It is widely used to detect biotinylated probes, because it reportedly exhibits less nonspecific binding than does the glycosylated, biotin-binding protein, avidin.