The Oyster®-650-Streptavidin is a bright, red fluorescent conjugate, which is excitated best by the 633 nm line of a He-Ne laser or the 647 nm of a Kr-Ar laser. Streptavidin is a non-glycosylated biotin-binding protein with a iso-electric point near pH 7.0. Oyster®-650 is spectrally similar to Cy5 ™ or Alexa Fluor ® 647.