Debrancher enzyme

P-amylase, and debranching enzymes. Conversion of D-glucose to D-fmctose is mediated by glucose isomerase, mosdy in its immobilized form in columns. Enzymic degradation of starch to symps has been well reviewed (116—118), and enzymic isomerization, especially by immobilized glucose isomerase, has been fiiUy described (119) (see Syrups). 

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... 

The glycogen phosphorylase reaction degrades glycogen to produce limit dextrins, which are further degraded by debranching enzyme, as already described. 

Type III Limit dextrinosis, Forbes or Corl s disease Absence of debranching enzyme Accumulation of a characteristic branched polysaccharide. 

Tabata, S. and Dohi, Y., An assay for oligo-(l—>4) —5(1—>4)-glucantransferase activity in the glycogen debranching enzyme system by using HPLC with a pulsed amperometric detector, Carb. Res., 230,179, 1992. 

Amylo-1 —> 6-glucosidase obtained by Cori and Larner218 from rabbit muscles, and R-enzyme isolated by Hobson, Whelan and Peat219 from potatoes and broad beans, are typical debranching enzymes, which will hydrolyze the 6 — 1-a-D-glucosidic linkage rather than the normal 4 —> 1-a-D linkage. These enzymes will therefore be particularly important in determinations of the fine structure of amylopectin, if they can be sufficiently well purified. 

Debranching enzyme hydrolyzes the a1,4-bond nearest the branch point as shown. 

Debranching enzyme deconstructs the branches in glycogen that have been exposed by glycogen phosphorylase. The two-step process by which this occurs is diagrammed in Figure 1-14-4. Debranching enzyme ... 

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

Answer D. This activity of the debranching enzyme removes 1,6-linked glucose residues from the branch points during glycogenolysis. 

DEBRANCHING ENZYME AMYLOSUCRASE Anaerobic fermentation rate,... 

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