APTS is a very useful green fluorescent dye for labeling glycoproteins or sugar molecules in general. The labeling occurs via reductive amination which involves the formation of a Schiff base between the amine of APTS and the aldehyde or ketone of the sugar, followed by the reduction of the Schiff base linkage to a stable carbon-nitrogen bond. The multi-anionic nature of the dye makes it ideal for the studies of carbohydrate molecules by high resolution capillary electrophoresis.
