Glycogen, 0-amylase action enzymic degradation

II. The Enzymic Degradation of Starch and Glycogen 1. Action of Amylase... 

PRODUCTS OF THE ENZYMIC DEGRADATION OF STARCH AND GLYCOGEN 295 4. Action of Taka-amylase ... 

The linkages of amylopectin and glycogen provide the cell with a glucose polysaccharide that upon action by degradative enzymes, such as amylases, isoamylases, debranching enzymes, or phosphorylases are easily converted into glucose and or a-Glc-1-P. 

As shown above, the /3-amylases cannot cleave or by-pass the 1- 6 glu-cosidic linkages of amylopectin or glycogen. There is an indication from their action that amylose also has links other than the 1- 4 a-glucosidic linkages (100), Whereas crude /3-amylase can completely degrade pure amylose if retrogradation is avoided, purified /3-amylases (crystalline sweet potato and an amorphous soybean /3-amylase) are reported to degrade amylose fractions from several sources only to the extent of 70%. A /3-glu-cosidase, Z-enzyme, was obtained from the crude soybean amylase which was able to attack the anomalous links. 

With some natural starches or with glycogen it is possible that the action of the /5-amylase is stopped before all end chains are removed because the substrate molecule has so complicated a network of chains that the enzyme, which presumably has a large molecule, can not penetrate into the inner parts of the substrate molecule. This point has been stressed in the case of glycogen by Meyer and Jeanloz. These authors degraded the substrate by a short treatment with hydrochloric acid to the extent that all end chains were accessible for the enzyme and a true saccharification limit was reached. Experiments with different starches and... 

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