Figure 1.

General principle of enzymatic cascades allowing the specific detection of carbohydrates. Different monosaccharide components of an oligosaccharide (depicted as colored hexagons) make up a natural substrate, the degradation of which cannot be directly monitored by optical means. When the targeted enzymatic activity releases (1) specific carbohydrates (blue hexagons) from a natural substrate, their emergence is detected with a specific coupling reaction (or alternatively a cascade of coupling reactions) (2). The coupling system generates a product (blue halo) that can be readily monitored by its absorbance or fluorescence.