Deglycosylated Avidin (Avidin D) was Fluorescein labeled and further purified to obtain a cell sorting grade of Fluorescein Avidin D preparation. Using new fluorescein labeling techniques, more fluorochrome was incorporated into the protein without altering its binding properties. The higher ratio of fluorochrome to protein increases the efficiency of fluorescence using this improved conjugation technique, and additionally, we reduced nonspecific binding for better resolution in cell sorting (CS) and other applications. This conjugate can also be used in fluorescent microscopy when higher sensitivity and lower background staining are desired. Using further amplification procedure withBiotinylated Anti-Avidin D antibody significant gain in signal intensity can be achieved. Fluorescein Avidin-D has an excitation at 495 nm and an emission at around 515 nm and its binding characteristics are similar to the native avidin. Supplied in liquid form with stabilizers and preservatives. Shipped on blue ice.