Amylopectin-1,6-glucosidase

Indeed, some enzymes, e.g. amylopectin, glucosidase, p-amylase, and phosphatase (Shain and Mayer, 1968 Rowsell and Good, 1962 Presley and 242... 

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. 

More specific hydrolysis may be achieved by the use of enzymes. Thus, the enzyme a-amylase in saliva and in the gut is able to catalyse hydrolysis of al 4 bonds throughout the starch molecule to give mainly maltose, with some glucose and maltotriose, the trisaccharide of glucose. Amylose is hydrolysed completely by this enzyme, but the al 6 bonds of amylopectin are not affected. Another digestive enzyme, a-l,6-glucosidase, is required for this reaction. Finally, pancreatic maltase completes the hydrolysis by hydrolysing maltose and maltotriose. 

The glucosidase activity alone was measured by 14C-glucose incorporation into polymer (16) and the transferase activity alone was measured by the change in the iodine spectrum of amylopectin (20). 

Non-reducing fructose derivative sweeteners. A Hyashibara process (12) subjects a mixture of starch and sucrose to cyclodextringlucosyl-transferase and amylopectin-a-1,6-glucosidase (such as pullulanase or isoamylase). Cyclodextrins are formed as intermediates, but then act as glucosvl donors for attachment to the glucose portion of the... 

The latest International Union Biochemicals report includes an enzyme 3.2.1.41 a-dextrin endo-l,6-a-glucosidase, other names limit dextrinase, amylopectin 6-glucanohydrolase, pullulanase. 

Both amylose and amylopectin are hydrolyzed to glucose with cleavage of the glycosidic bonds. The human digestive system has the necessary a-glucosidase enzymes needed to catalyze this process. Bread and pasta made from wheat flour, rice, and corn tortillas are all sources of starch that are readily digested. 

In the method of Cori and Lamer, glycogen (or amylopectin) is completely digested by the concurrent action of muscle phosphorylase and amylo-(l 6)-glucosidase. n-Glucose (which arises only from residues attached to C6 of an adjacent residue) and n-glucosyl phosphate (which is obtained from all other residues) are determined, and the branch-point content is calculated from the proportion of D-glucose. Only 10-15 mg. of glycogen is required for each assay the method has been applied to more... 

Figure 13.16 Sequential digestion of amylopectin or glycogen by ff-amylase and ff(l-6)-glucosidase. 

The breakdown of starch (amylose and amylopectin) also requires two enzymes, ot-amylase, and ot(l ->6) glucosidase (another "debranching enzyme"). ot-Amylase cleaves... 

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