Glycogen, 0-amylase action

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

Fig. 9.—Radioautograph of paper chromatogram showing radioactive Schardinger dextrins produced from radioactive glycogen by B. macerans amylase. Small amounts of linear oligosaccharides together with unreacted residues from the glycogen were removed by beta amylase action and converted to maltose and maltotriose.

Fig. 4.—Structures Around the Outermost Branch-points in the Limit Dextrins Remaining After Action of foeta-Amylase on Amylopectin and Glycogen. [Structure (b) is obtained uniquely by foeta-amylase action on phosphorylase limit-dextrins (see p. 315). For an explanation of the symbols, see footnote 49.]...

It has been reported that glycogens contain, in addition to D-glucose xmits, nitrogen, phosphorus, and uronic acid groups, but these reports have not been substantiated. Maltulose has been isolated from the products of a-amylase action on rabbit liver glycogen (25). 

Because of the difficulties involved in separating the isoenzymes among themselves and from other enzymes such as amylases, it is not yet clear what the best acceptors are and what the products are for each isoenzyme, but some characterization of the enzymes has been done (e.g., Km for a-glucans such as amylopectin, different animal glycogens, and maltosaccha-rides). Characterization of the products has been minimal, but some progress has been made in our laboratory (see the next section, Mode of Action ). 

After earlier workers had indicated the existence of several amylases in malt, conclusive evidence that the malt amylase is composed of at least two starch-splitting enzymes was furnished by Ohlsson. Both enzymes are capable of attacking starch and glycogen, but their action is very different. One enzyme, termed saccharogenic amylase by Ohls-... 

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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