Sequential cleavage from the non-reducing terminals of glucose molecules is required for both glycogen degradation and polysaccharides hydrolysis.
Why non-reducing end is selected for digestion?
A polysaccharide's non-reducing end is the one where an anomeric carbon participates in the glycosidic connection. The elimination of carbohydrate remnants one at a time out from the non-reducing terminal occurs during glycogenolysis and polysaccharides hydrolysis.
For example, several enzymes are involved in glycogenolysis in the liver and muscle.
An example of such an enzyme is glycogen phosphorylase, which catalyzes the successive dissociation of the alpha 1->4 glycosidic bond that connects two glucose molecules at a non-reducing terminal of glycogen. The last glucose residue is eliminated as alpha-D-glucose 1-phosphate.
That is why non-reducing end of glucose is chosen for digestion or breakdown of the carbohydrate polymer.
