Glycogen 1,4-chain

Branching Involves Detachment of Existing Glycogen Chains... 

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). 

In addition to the direct energy cost for the synthesis of a protein, there are indirect energy costs—those required for the cell to make the necessary enzymes for protein synthesis. Compare the magnitude of the indirect costs to a eukaryotic cell of the biosynthesis of linear (al—>4) glycogen chains and the biosynthesis of polypeptides, in terms of the enzymatic machinery involved. 

Glycogen phosphorylase sequentially cleaves the cx(1 -h>4) glycosidic bonds between the glucosyl residues at the nonreducing ends of the glycogen chains by simple phosphorolysis until four glucosyl units remain on each chain before a branch point (Figure 11.7). [Note ... 

Enzyme that adds glucose to the ends of glycogen chains... 

Formation of glycogen chains by glycogen muscle phosphorylase and starch amylose by potato phosphorylase. 

Glycogen is believed to be a proteoglycan, as glycogen chains appear to require a backbone primer protein on... 

Glucose units are removed from the nonreducing ends of glycogen chains by phosphorylase, which produces glucose 1-phosphate. 

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