Glycogen glucose residues

Fig. 11-13 The formation of branched chains of glucose residues within glycogen. — = glucose residue.

FIGURE 23.15 The reactions of glycogen debranching enzyme. Transfer of a group of three o -(l 4)-linked glucose residues from a limit branch to another branch is followed by cleavage of the o -(l 6) bond of the residue... 

Figure 13-13. The glycogen molecule. A General structure. B Enlargement of structure at a branch point. The molecule is a sphere approximately 21 nm in diameter that can be visualized in electron micrographs. It has a molecular mass of 10 Da and consists of polysaccharide chains each containing about 13 glucose residues. The chains are either branched or unbranched and are arranged in 12 concentric layers (only four are shown in the figure). The branched chains (each has two branches) are found in the inner layers and the unbranched chains in the outer layer. (G, glycogenin, the primer molecule for glycogen synthesis.)...

Figure 18-7. Control of glycogen synthase in muscle (n = number of glucose residues). The sequence of reactions arranged in a cascade causes amplification at each step, allowing only nanomole quantities of hormone to cause major changes in glycogen concentration. (GSK, glycogen synthase kinase-3, -4, and -5 G6P, glucose 6-phosphate.)...

The next step involves a transfer of the glucose residue from UDP-glucose onto the glycogen primer through the aid of the enzyme glycogen synthetase ... 

Branches are created by forming glycosidic linkages with both the 4- and 6-hydroxyl groups of the glucose residue at the branch point. The glycogen polymer is very large and contains multiple branches. 

III Cori Glycogen debranching enzyme Mild hypoglycemia, liver enlargement Short outer branches Single glucose residue at outer branch... 

Glycogen synthase now transfers glucose residues one by one from UDP-glucose to the non-reducing ends of the available branches. ... 

Cellulose, a fibrous, tough, water-insoluble substance, is found in the cell walls of plants, particularly in stalks, stems, trunks, and all the woody portions of the plant body. Cellulose constitutes much of the mass of wood, and cotton is almost pure cellulose. Like amylose and the main chains of amylopectin and glycogen, the cellulose molecule is a linear, unbranched homopolysaccharide, consisting of 10,000 to 15,000 D-glucose units. But there is a very important difference in cellulose the glucose residues have the /3 configuration (Fig. 7-16),... 

FIGURE 15-3 Removal of a terminal glucose residue from the nonreducing end of a glycogen chain by glycogen phosphorylase. This process is repetitive the enzyme removes successive glucose residues until it reaches the fourth glucose unit from a branch point (see Fig. 15-4). 

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