Improved Method for Detecting Fluorescent-Labeled Glycoprotein on Sodium Dodecyl Sulfate–Polyacrylamide Gel

An improved method for detecting glycoproteins labeled with fluorescent probe on SDS–polyacrylamide gel has been developed based on the previous method we reported previously. In the current method, instead of dansyl glycyl hydrazide (DNS-GLY-NHNH2), fluorescein 5-thiosemicarbazide with a high extinction coefficient and fluorescence quantum yield was employed to label glycoprotein covalently, and the fluorescent staining of glycoproteins on the gel after SDS–PAGE used in the previous method was replaced by the fluorescent labeling of protein samples before electrophoresis to save the fluorescent probe and to shorten the experiment period. Labeled glycoproteins can be detected clearly under ultraviolet illumination after electrophoresis. The examination of several known glycoproteins indicated that the limiting detective sensitivity in the current method was about 1–2 ng of glycoproteins tested, 10–20 times higher than that in the previous method.